JP2008270399A - Optical signal amplification 3-terminal device - Google Patents

Abstract

An optical signal amplification three-terminal device using a negative feedback optical amplification effect capable of converting an electrical input signal into an optical signal and amplifying the optical output signal with less noise.
An optical input signal SP1 having a first wavelength λ1 converted from an electric input signal SE1 and an inverted optical input signal having a second wavelength λ2 converted from an inverted electric input signal SE2 obtained by inverting the electric input signal SE1. SP2 is combined with the optical coupler 16 and input to the optical signal amplifying element 18, and the optical output signal SP3 of the first wavelength λ1 selected from the optical signals output from the optical signal amplifying element 18 is converted into an electric signal. It is converted and output as an electrical output signal SE3. The optical output signal output from the optical signal amplifying element 18 and the electrical output signal SE3 converted from the optical output signal 18 have a low baseline level, a sufficiently high degree of modulation, S / N ratio, and input / output amplitude amplification ratio. The signal is sufficiently low.
[Selection] Figure 1

Description

  The present invention relates to an optical signal amplification three-terminal device utilizing a negative feedback optical amplification effect capable of reducing distortion and noise when an electrical signal is converted into an optical signal for amplification and transmission. is there.

  In the technical field where electric signals are converted into optical signals for amplification and transmission, the converted optical signals are very different from electric signals based on the conversion characteristics of electric / optical conversion elements such as semiconductor lasers and light emitting diodes. It is known to distort. In particular, when a pulsed electric signal is input to the semiconductor laser, the optical signal intensity rapidly increases at the rise of the pulse of the output optical signal, and an optical signal waveform overshooting like a beard is obtained. Generally, when these optical signal waveforms are amplified by an optical amplifier, the distortion is amplified and transmitted, and a technique for optically reducing the distortion has not been obtained.

On the other hand, Maeda of the present inventor uses the mutual gain modulation phenomenon of the semiconductor optical amplifier (SOA), and the ambient light after passing through the semiconductor optical amplifier with respect to the input optical signal of the predetermined wavelength λ1 (centered on λ1). It is shown that the input optical signal can be amplified with low distortion by feeding back the wavelength other than λ1 to the input side, and named negative feedback optical amplification effect (Non-patent Document 1) . This effect is that the ambient light exhibits intensity inversion with respect to the input optical signal by XGM (mutual gain modulation), so that the gain of the semiconductor optical amplifier is modulated according to the input optical signal by feeding back this ambient light. A negative feedback light amplification effect can be obtained. In addition, as shown in Patent Document 1, it has been proposed to apply an optical amplifier using this effect to an effector.
"Negative feedback optical amplification effect based on cross-gain modulation in semiconductor optical amplifiers" (Applied Physics Letters, Volume 88, published 8 March 2006) JP 2006-332344 A JP-A-8-125605

  By the way, in the conventional optical amplifier using the negative feedback light amplification effect, a method of feeding back ambient light or light strengthening the ambient light is used. Such a system is optically simple and useful, but only has an effect of amplifying an optical signal with low distortion and low noise. When an electric signal is converted into an optical signal, an electric / optical conversion element is used. Even the distortion of the generated optical signal cannot be removed. For this reason, there has been a disadvantage that the distortion of the optical signal that occurs when the electrical signal is converted into the optical signal cannot be removed.

  On the other hand, there has been proposed an apparatus using optical modulation that reduces waveform degradation of a signal wave such as distortion generated during signal transmission. For example, this is the optical communication system described in Patent Document 2. The apparatus includes a first light modulating unit that generates first signal light that is intensity-modulated in accordance with binary signal data, and an inverting unit that inverts the binary signal data and outputs an inverted binary signal. And second optical modulation means for generating a second signal light that is an optical signal having a wavelength different from the wavelength of the first signal light and is intensity-modulated in response to the inverted binary signal And optical multiplexing means for multiplexing the first signal light and the second signal light and sending the combined signal light to an optical fiber transmission line. According to the apparatus configured as described above, the first signal light intensity-modulated corresponding to the binary signal data and the second signal intensity-modulated corresponding to the inverted signal of the binary signal data at the same time. The frequency at which the signal light is transmitted to the optical fiber transmission line and the change in the refractive index of the fiber due to the change in the intensity of the first signal light (self-phase modulation effect) causes the change in the intensity of the second signal light to the first signal light Waveform deterioration of the first signal light that is canceled by the displacement and propagates through the optical fiber transmission line is eliminated.

  However, in the apparatus using the optical modulation of Patent Document 2, the refractive index of the fiber due to the change in the intensity of the first signal light is utilized by utilizing the property that the refractive index of the optical fiber changes according to the intensity of the signal light. The change (self-phase modulation effect) is canceled by the frequency displacement that the intensity change of the second signal light brings to the first signal light, so that the signal wave such as distortion generated during signal transmission is deteriorated. Although improved, the signal light is not amplified because the optical fiber transmission path through which the combined optical signal light of the first signal light and the second signal light is transmitted is composed of a simple optical fiber. Further, the S / N ratio, amplitude amplification, and error rate of the output signal light cannot be sufficiently improved.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide an optical signal amplification three-terminal device capable of amplifying an electrical output signal to an optical output signal with less noise. It is in.

  In light of the above circumstances, the present inventor includes an output signal light having a predetermined wavelength and an ambient light having an ambient wavelength of the predetermined wavelength when an optical signal is amplified using an optical signal amplifying element having a mutual gain modulation characteristic. While selecting and outputting the output signal light of the predetermined wavelength from the output light, a part or all of the ambient light whose phase is inverted at a wavelength different from the output signal light of the predetermined wavelength is negatively fed back. As we continue to research to stabilize the gain and baseline of the optical signal or eliminate noise by re-inputting it to the optical signal amplifying element, instead of negative feedback light re-input to the optical signal amplifying element, the input signal It has been found that when inverted light is input to the optical signal amplifying element, signal light having a high S / N ratio and output / input amplitude amplification ratio and a sufficiently low error rate can be obtained. The present invention has been made based on such knowledge.

  That is, the gist of the invention according to claim 1 is an optical signal amplification three-terminal device using a negative feedback optical amplification effect for converting an electric input signal into an optical signal and amplifying it, wherein (a ) A signal inverting element that inverts and outputs the electrical input signal; and (b) converts the electrical input signal into an optical input signal having a first wavelength and outputs the inverted electrical input signal output from the signal inverting element to the first. An electric / optical conversion element for converting into an inverted optical input signal having a second wavelength different from the wavelength; (c) an optical signal amplification element having a negative feedback optical amplification effect; and (d) an output from the electric / optical conversion element. An optical coupler for combining the input optical signal and the inverted optical input signal to be input to the optical signal amplifying element; and (e) the first wavelength or the second wavelength of the light output from the optical signal amplifying element. And a wavelength selection element that selects the optical signal.

  According to the optical signal amplification three-terminal device using the negative feedback optical amplification effect of the invention according to claim 1, the optical input signal of the first wavelength converted from the electric input signal and the inversion in which the electric input signal is inverted The inverted optical input signal of the second wavelength converted from the electrical input signal is combined with the optical coupler and input to the optical signal amplification element, and is selected by the wavelength selection element from the optical signal output from the optical signal amplification element The optical signal having the first wavelength or the second wavelength is output. The optical signal output from the optical signal amplifying element has a low baseline level due to its negative feedback optical amplification effect, a high degree of modulation, an S / N ratio, an input / output amplitude amplification ratio, and a sufficiently low error rate. Therefore, an optical output signal having a sufficiently high S / N ratio and output / input amplitude amplification ratio and a sufficiently low error rate can be obtained.

  Here, preferably, the optical signal of the first wavelength or the second wavelength selected by the wavelength selection element from the optical signal output from the optical signal amplification element has a high degree of modulation with respect to the electrical input signal. Have. In this way, an optical output signal having a sufficiently high S / N ratio and output / input amplitude amplification ratio and a sufficiently low error rate can be obtained.

  Preferably, the optical signal amplifying element comprises an optical fiber doped with a rare earth element. In this way, a signal amplification operation can be performed with low power, and an electrical output signal with a high input / output amplitude amplification ratio and a high S / N ratio and a low error rate can be obtained particularly in a low frequency region.

  Preferably, the optical fiber is doped with erbium. In this way, an electrical output signal having a high input / output amplitude amplification ratio and an S / N ratio and a low error rate can be obtained with respect to an optical signal having a wavelength of 1.5 μm band used in optical communication.

  Preferably, the optical fiber preform is made of a fluoride. By doing so, it is possible to increase the doping amount of the rare earth element to shorten the lifetime of the excited level electrons, and to increase the upper limit value of the operating frequency band to about 20 kHz. In addition, the distortion rate can be reduced.

  Preferably, the optical signal amplifying element is a semiconductor optical signal amplifying element having an active layer composed of a pn junction. In this way, the optical amplifying element can be easily downsized or made into one chip by a semiconductor, and signal amplification is possible even in a high frequency band of GHz order based on its high responsiveness.

  Preferably, the active layer of the semiconductor optical signal amplifying element is composed of any one of a quantum well, a strained superlattice, and a quantum dot. In this way, the optical signal amplifying element can be easily miniaturized by a semiconductor, and when the quantum well or quantum dot is used, the high-speed switching performance of the optical signal amplifying element is enhanced, and a strained superlattice is used. In this case, an optical signal amplifying element having a small wavelength dependency is obtained.

  Preferably, the wavelength selection element includes any one of an optical add / drop filter, an optical filter having a multilayer structure, a grating filter, and a photonic crystal filter. In this way, the first wavelength and the second wavelength are efficiently separated from the output signal light from the optical signal amplifying element.

  Preferably, the optical coupler includes an optical add / drop element. In this way, by using the optical add / drop element, the optical signals of the first wavelength and the second wavelength input to the optical signal amplifying element are efficiently multiplexed.

  Preferably, the electrical input signal is an audio input signal that represents sound in an analog manner. In this way, the speaker can be driven by an electrical output signal having a sufficiently high S / N ratio and an input / output amplitude amplification ratio and a sufficiently low error rate, so that high sound quality can be obtained.

  Preferably, the electric / optical conversion element is a semiconductor laser or a light emitting diode whose output light is controlled in response to the electric input signal. In this way, the electric input signal can be easily converted into an optical signal.

  Preferably, the optical signal amplification three-terminal device using the negative feedback light amplification effect is used as an audio preamplifier or an audio effector. In this way, it is possible to obtain high-quality sound with no noise, a sense of depth, and a reverberation.

  Preferably, the optical signal element may be composed of two or more optical signal amplifying elements.

  Preferably, the optical signal amplification three-terminal device further includes an optical / electric conversion element that converts the optical signal selected by the wavelength selection element into an electrical signal and outputs the electrical signal as an electrical output signal. By doing so, the electrical output signal output from the photoelectric conversion element has a high degree of modulation with respect to the electrical input signal, so that the S / N ratio and the output / input amplitude amplification ratio are sufficient. And an electrical output signal with a sufficiently low error rate.

  In addition, the electrical output signal output from the photoelectric conversion element has a high degree of modulation with respect to the electrical input signal. In this way, an optical output signal having a sufficiently high S / N ratio and output / input amplitude amplification ratio and a sufficiently low error rate can be obtained.

  Preferably, the photoelectric conversion element converts an optical signal into an electrical signal having an intensity corresponding to the signal, such as a phototransistor element, a photodiode element, a solar battery cell, or a photoelectric cell. If it is.

  Hereinafter, an optical signal amplification three-terminal device 10 using a negative feedback optical amplification effect according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, an optical signal amplification three-terminal device 10 receives, for example, an electrical input signal SE1, which is an audio signal representing an acoustic waveform as an analog signal, converts it into an optical signal, and amplifies it using a negative feedback optical amplification effect. Is output as an electrical output signal SE3. The optical signal amplification three-terminal device 10 is composed of, for example, an operational amplifier functioning as an inverting amplifier. The signal inverting element 12 that outputs an inverted electric input signal SE2 obtained by inverting the electric input signal SE1 is different in, for example, two types of output wavelengths. The semiconductor laser diode or LED is used to convert the electrical input signal SE1 into an optical input signal SP1 having a first wavelength λ1, and the inverted electrical input signal SE2 is inverted to a second wavelength λ2 different from the first wavelength λ1. An electro / optical conversion element 14 for converting to an optical input signal SP2, an optical coupler 16 for multiplexing the optical input signal SP1 and the inverted optical input signal SP2, and an optical input signal SP1 and inverted by the optical coupler 16 The optical input signal SP2 is received and optically amplified according to the negative feedback optical amplification effect, and the signal light having the first wavelength λ1 and the first wavelength λ1 are obtained. An optical signal amplifying element 18 for outputting ambient light (naturally generated light) in a frequency band including the second wavelength λ2 centered on the center and capable of mutual gain modulation and excluding the first wavelength λ1, and the optical signal A wavelength selecting element 20 that selects an optical signal having the first wavelength λ1 from the light output from the amplifying element 18 and outputs it as an optical output signal SP3, and a phototransistor element, a photodiode element, a solar battery cell, a photoelectric cell, etc. And an optical / electrical conversion element 22 that converts the optical output signal SP3 output from the wavelength selection element 20 into an electrical signal and outputs the electrical signal as an electrical output signal SE3. The second wavelength λ2 of the inverted light input signal SP2 is set within the band of the ambient light. For example, if the first wavelength λ1 of the optical input signal SP1 is about 1550 nm, the second wavelength λ2 of the inverted optical input signal SP2 is about 1530 to 1545 nm, or about 1555 to 1570 nm.

The optical signal amplifying element 18 is composed of an optical fiber doped with a rare earth element such as erbium, or a pn junction, and has a quantum well, a strained superlattice, or a quantum dot structure active layer in an optical waveguide. It is composed of an amplifying element. The optical fiber can be used as an amplifier in a frequency band of about 10 kHz or less as long as it is made of silicate glass using SiO ₂ as a base material. The erbium doping amount can be increased, the response is improved, and the frequency band usable as an amplifier is expanded up to about 20 kHz.

  In the optical signal amplifying element 18, when light having a frequency that can be induced and radiated determined by a predetermined energy level constituted by a dopant, that is, an optical input signal SP 1 having the first wavelength λ 1 shown in FIG. The optical input signal SP1 is about to be amplified by stimulated radiation, but the amplification factor increases as the intensity of the inverted optical input signal SP2 having the second wavelength λ2 shown in FIG. The mutual gain modulation effect of lowering works. That is, since the inverted optical input signal SP2 has the second wavelength λ2 within the wavelength band of the ambient light of the first λ1 of the optical input signal SP1, when it is incident on the optical signal amplifying element 18, FIG. c) Since the gain (amplification factor) of the optical input signal SP1 having the first wavelength λ1 is decreased as shown in FIG. 6B, the optical input signal SP1 functions as negative feedback light. The solid line in FIG. 2 (c) shows this state, and the dotted line is the case where negative feedback light (inverted light input signal SP2) is not input, and the gain is constant. Further, the inverted optical input signal SP2 is inverted light having the same large amplitude as the optical input signal SP1 because the optical input signal SP1 is inverted by the input signal converter 12. For this reason, as shown in FIG. 2 (d), when the optical input signal SP1 of the first wavelength λ1 and the inverted optical input signal SP2 of the second wavelength λ2 whose phase is inverted are incident on the optical signal amplifying element 18. The optical output signal SP3 having the first wavelength λ1 selected from the output light of the optical signal amplifying element 18 is not only stabilized, but also the inverted optical input signal SP2 functioning as the negative feedback light is the optical input signal SP1. Therefore, the optical output signal SP3 output from the optical signal amplifying element 18 is lower in the base line level than the case where the negative feedback light indicated by the dotted line is not input. , The modulation degree M, the S / N ratio, the input / output amplitude amplification ratio are sufficiently high, and the signal light has a sufficiently low error rate. Therefore, by converting the optical output signal SP3 by the optical / electrical conversion element 22, an electrical output signal SE3 having a sufficiently high S / N ratio and output / input amplitude amplification ratio and a sufficiently low error rate can be obtained. .

  The optical coupler 16 is composed of an optical add / drop element and multiplexes the optical input signal SP1 and the inverted optical input signal SP2. The wavelength selection element 20 includes any one of an optical add / drop filter, a multilayer optical filter, a multilayer reflective plate, a grating filter, and a photonic crystal filter, and is output from the optical amplification element 18. The optical signal having the first wavelength λ1 is selected and output from the received light.

Hereinafter, experimental results conducted by the present inventor will be described. Here, when the maximum voltage of the signal is V _max and the minimum voltage of the signal is V _min , the modulation degree M is defined as (V _max −V _min ) / (V _max + V _min ), and the modulation degree ratio MR is Is defined as (modulation degree M3 of electrical output signal SE3 or optical output signal SP3 / modulation degree M1 of electrical input signal SE1 or optical input signal SP1). The output input voltage ratio is defined as (voltage of electrical output signal SE3 or optical output signal SP3 / voltage of electrical input signal SE1 or optical input signal SP1), that is, amplification factor. The distortion rate (%) is defined as [(harmonic (voltage) / fundamental wave (voltage)] × 100.

3 to 6 show an optical signal amplification three-terminal device 10 as shown in FIG. 1 using an optical signal amplification element 18 composed of an optical fiber made of silica (SiO ₂ ) glass doped with several hundred ppm of erbium. The modulation degree ratio MR, output input voltage ratio, S / N ratio, and bit error rate BER of the electrical output signal SE3 obtained when the frequency of the electrical input signal SE1 is changed, and the inverted optical input signal SP2 are This is shown in comparison with the case where the optical signal amplifying element 18 is not input. 3 to 6, data points when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 (SE2 = 5V) are indicated by で, and the inverted optical input signal SP2 is converted to the optical signal amplifying element 18. Data points when not input to (SE2 = 0V) are indicated by □. As shown in FIGS. 3 to 6, when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 particularly in a low frequency region of 10 kHz or less, that is, an audible frequency region, the inverted optical input signal SP2 is transmitted as an optical signal. Compared with the case where the signal is not input to the signal amplifying element 18, the modulation ratio MR, the output input voltage ratio, and the S / N ratio are significantly high, and the bit error rate BER is significantly low. For example, with respect to the modulation factor ratio MR, as shown in FIG. 3, an improvement is seen in the modulation factor ratio MR when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 at 200 Hz or less, and the signal frequency is increased. The lower the difference, the greater the difference. As for the output / input voltage ratio, as shown in FIG. 4, an increase in the output / input voltage ratio is observed when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 at 2 to 3 kHz or less. In the following, about 5 times amplification is seen. As for the S / N ratio, as shown in FIG. 5, an increase in the S / N ratio is observed when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 at 2 to 3 kHz or less. As for the bit error rate BER, as shown in FIG. 6, when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 at 20 kHz or less, a decrease in the bit error rate BER is observed, and the electric input signal SE1 The difference increases with decreasing frequency. When the inverted optical input signal SP2 is input to the optical signal amplifying element 18, the bit error rate BER is low and 10 ⁻⁷ or less, whereas the inverted optical input signal SP2 is not input to the optical signal amplifying element 18 The bit error rate BER increases as the frequency of the electrical input signal SE1 decreases.

FIG. 7 shows a case where the optical signal amplification three-terminal device 10 is configured as shown in FIG. 1 by using the optical signal amplification element 18 composed of an optical fiber made of the erbium-doped silicate (SiO ₂ ) glass. An optical input signal SP1, an inverted electrical input signal SE2, an inverted optical input signal SP2, and an electrical output signal SE3 (optical output signal SP3) obtained when a 100 Hz electrical input signal SE1 is input are shown on the time axis. Yes. Although the optical input signal SP1 in which the waveform of the electrical input signal SE1 is distorted is generated by the characteristics of the laser diode constituting the electro / optical conversion element 14, as is clear from FIG. 7, the optical output signal SP3 having a small waveform distortion, that is, An electrical output signal SE3 is obtained.

FIG. 8 shows a case where the optical signal amplifying three-terminal device 10 is configured as shown in FIG. 1 using the optical signal amplifying element 18 composed of an optical fiber made of silica (SiO ₂ ) glass doped with erbium. Modulation that is the ratio of the modulation degree M1 of the electrical input signal SE1 and the modulation degree M3 of the electrical output signal SE3 obtained when the magnitude (V _PP ) of the inverted electrical input signal SE2 (inverted optical input signal SP2) is changed A change in the degree ratio MR (= M3 / M1) is shown. Thus, it can be seen that a stable modulation degree ratio MR can be obtained when the inverted electric input signal SE2 is 3 to 5 V _PP , and the modulation degree ratio MR can be controlled using the inverted electric input signal SE2.

  Next, as shown in FIG. 1, an optical signal amplifying element 18 composed of an optical fiber containing erbium with a high concentration, for example, about 1000 to 3000 ppm by constituting a glass base material with fluoride is used. Characteristics obtained when the three-terminal device 10 is configured will be described with reference to FIGS. 9 to 11.

9 and 10 show an optical signal amplification three-terminal device 10 as shown in FIG. 1 using an optical signal amplification element 18 composed of an optical fiber containing a high concentration of erbium with the above fluoride glass. The output input voltage ratio obtained when the frequency of the electrical input signal SE1 is changed when the magnitude (V _PP ) of the inverted electrical input signal SE2 (inverted optical input signal SP2) is 0V, 1V, and 5V. And S / N ratio are shown respectively. In FIG. 9, the output input voltage ratio is shown in comparison with the case where the inverted optical input signal SP2 is not input to the optical signal amplifying element 18, that is, the inverted electrical input signal SE2 is 0V. When the inverted optical input signal SP2 is input to the optical signal amplifying element 18 at about 20 kHz or less, an increase in the output / input voltage ratio is observed. In particular, the output input voltage ratio increases as the inverted electrical input signal SE2 increases at 800 Hz or less. When the inverted electrical input signal SE2 is 5V, amplification with an output input voltage ratio of about twice is observed. The effect is confirmed even at a frequency of 20 kHz or higher. That is, it responds to a higher frequency than silicate glass. In FIG. 10, the S / N ratio is shown in comparison with the case where the inverted optical input signal SP2 is not input to the optical signal amplifying element 18, that is, the inverted electrical input signal SE2 is 0V. An increase in the S / N ratio is observed when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 at about 2 kHz or less. In particular, the S / N ratio increases as the inverted electrical input signal SE2 increases at 800 Hz or less. .

  FIG. 11 shows an optical signal amplifying three-terminal device as shown in FIG. 1 using an optical signal amplifying element 18 composed of an optical fiber containing a high concentration of erbium by making the glass base material a fluoride. 10 and when the optical signal amplification three-terminal device 10 is configured as shown in FIG. 1 using an optical signal amplification element 18 composed of an optical fiber made of silicate glass doped with erbium, The distortion rate (%) obtained when the frequency of the electric input signal SE1 is changed is shown. As shown in FIG. 11, the distortion rate increases as the frequency decreases in the region of 10 kHz or less, and becomes saturated in the region of several hundred Hz or less. However, the optical fiber in which fluoride glass contains a high concentration of erbium. When the optical signal amplifying element 18 composed of () is used, the optical signal amplifying element 18 composed of an optical fiber containing erbium in a silicate glass is used (). The distortion rate is relatively small.

  Next, for example, the waveguide has an active layer composed of a pn junction and a quantum well, strained superlattice, or quantum dot, and is composed of a semiconductor that performs optical amplification using stimulated radiation. Characteristics when the optical signal amplification three-terminal device 10 is configured as shown in FIG. 1 using the optical signal amplification element 18 will be described below with reference to FIGS. 12 to 14.

  12 shows the negative feedback effect when the optical signal amplifying three-terminal device 10 is configured as shown in FIG. 1 using the optical signal amplifying element 18 composed of the semiconductor described above, and the frequency of the electric input signal SE1 is changed. FIG. 6 is a characteristic diagram showing the output / input voltage ratio obtained when the inverted optical input signal SP2 is input to the optical signal amplifying element 18 (SE2 = 5V), and the data points are indicated by ◇ and inverted. Data points when the optical input signal SP2 is not input to the optical signal amplifying element 18 (SE2 = 0V) are indicated by □. As shown in FIG. 12, when the inverted optical input signal SP2 is input to the optical signal amplifying element 18, a higher output / input voltage ratio is obtained in the entire region from about 80 kHz to 10 Hz as compared with the case where the inverted optical input signal SP2 is not input. can get.

  FIG. 13 shows the negative feedback effect when the optical signal amplifying three-terminal device 10 is configured as shown in FIG. 1 using the optical signal amplifying element 18 composed of the above semiconductor, and the frequency of the electric input signal SE1 is changed. FIG. 4 is a characteristic diagram showing a bit error rate BER obtained when the inverted optical input signal SP2 is input to the optical signal amplifying element 18, and the data points are indicated by ◇, and the inverted optical input signal SP2 is Data points when they are not input to the optical signal amplifying element 18 are indicated by □. As shown in FIG. 13, when the inverted optical input signal SP2 is input to the optical signal amplifying element 18, the bit error rate BER is low in the entire region from at least 25 kHz to 10 Hz, compared to the case where it is not input. Become. The difference in the bit error rate BER increases as the frequency of the electrical input signal SE1 decreases.

FIG. 14 shows the output / input voltage ratio (marked with ○) when the optical signal amplification three-terminal device 10 is configured as shown in FIG. 1 using the optical signal amplification element 18 composed of the semiconductor described above. It shows in comparison with. In FIG. 14, ◇ and Δ marks indicate the optical signal amplification three-terminal device 10 as shown in FIG. 1 using an optical signal amplification element 18 composed of an optical fiber made of erbium-doped silicate (SiO ₂ ) glass. The input / output voltage ratio in the case of a fiber having a high erbium concentration and a low fiber when configured is shown. In the low frequency range of several kHz or less, an input / output voltage ratio of 1.2 or more can be stably obtained in each of the above cases. The output / input voltage ratio indicated by ◯, the output / input voltage ratio indicated by ◇, Large values are obtained in the order of the input / output voltage ratios shown. However, in the frequency region higher than several kHz, the input / output voltage ratio indicated by Δ is a relatively low value. Also, the higher the erbium concentration, the higher the input / output voltage ratio up to a higher frequency.

  The optical signal amplification three-terminal device 10 configured as described above is preferably used as an audio preamplifier or an audio effector. FIG. 15 shows an example in which the optical signal amplification three-terminal device 10 is incorporated in an audio circuit. In FIG. 15, an optical signal amplification three-terminal device 10 is inserted as a preamplifier between a sound source 30 constituted by a reproduction device such as an MD player, a CD player, a receiver, and the power amplifier 32. When the electrical input signal SE1 that is an audio input signal output from the sound source 30 is input to the optical signal amplification three-terminal device 10, the S / N ratio and the output / input amplitude amplification ratio are sufficiently high according to the above-described operation, and An electrical output signal SE3 having a sufficiently low bit error rate and waveform distortion is output, and after it is amplified by the power amplifier 32, the speaker 34 is driven. As a result, a clear sound without noise, a sense of depth spreads, and a sound output in which a reverberant reverberation suitably appears can be obtained.

  As described above, according to the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of the present embodiment, the optical input signal SP1 of the first wavelength λ1 converted from the electrical input signal SE1 and the electrical input signal thereof The inverted optical input signal SP2 having the second wavelength λ2 converted from the inverted electrical input signal SE2 obtained by inverting SE1 is combined with the optical coupler 16 and input to the optical signal amplifying element 18, and the optical signal amplifying element Since the optical output signal SP3 of the first wavelength λ1 selected from the optical signal output from 18 is converted into an electrical signal and output as the electrical output signal SE3, the optical signal output from the optical signal amplifying element 18 Is a signal light having a low baseline level, a sufficiently high degree of modulation, an S / N ratio, and an input / output amplitude amplification ratio, and a sufficiently low error rate. N ratio, output Force amplitude amplification ratio is sufficiently high, and the error rate is sufficiently low electrical output signal SE3 obtained.

  Further, according to the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of the present embodiment, the electrical output signal SE3 output from the optical / electric conversion element 22 is higher than the electrical input signal SE1. Since it has a degree of modulation, an electrical output signal SE3 having a sufficiently high S / N ratio and output / input amplitude amplification ratio and a sufficiently low error rate can be obtained.

  Preferably, according to the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of the present embodiment, the optical signal amplification element 18 is an optical fiber whose base material is a silicate glass doped with a rare earth element. Therefore, the signal amplification operation can be performed with low power as compared with the semiconductor type optical amplifying element, and particularly in the low frequency region, the input / output amplitude amplification ratio and the S / N ratio are high and the error rate is high. A low electrical output signal SE3 is obtained.

  Further, according to the optical signal amplification three-terminal device 10 utilizing the negative feedback optical amplification effect of the present embodiment, the optical fiber constituting the optical amplification element 18 is doped with erbium. In this way, an electrical output signal SE3 having a high input / output amplitude amplification ratio and a high S / N ratio and a low error rate can be obtained with respect to an optical signal having a wavelength of 1.5 μm band used in optical communication. .

  In addition, according to the optical signal amplification three-terminal device 10 using the negative feedback light amplification effect of the present embodiment, the optical fiber preform constituting the optical amplification element 18 is made of fluoride. In this way, it becomes possible to increase the doping amount of the rare earth element to shorten the lifetime of the electrons at the excitation level, to increase the upper limit value of the operating frequency band to about 20 kHz, and to increase the distortion rate. Can be reduced.

  Further, according to the optical signal amplification three-terminal device 10 utilizing the negative feedback optical amplification effect of the present embodiment, the optical amplification element 18 is a semiconductor optical signal amplification element having an active layer composed of a pn junction. The optical amplification element can be easily downsized or made into one chip by a semiconductor, and low-noise signal amplification is possible even in a high frequency band of GHz order based on its high response.

  In addition, according to the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of the present embodiment, the active layer of the semiconductor optical signal amplification element constituting the optical amplification element 18 includes a quantum well, a strained superlattice, Since it is composed of either quantum dots, the optical signal amplifying element can be easily downsized by a semiconductor, and when the quantum well or quantum dot is used, the high-speed switching performance of the optical signal amplifying element is enhanced. When a strained superlattice is used, an optical signal amplifying element having a small wavelength dependency can be obtained.

  In addition, according to the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of this embodiment, the wavelength selection element 20 includes an optical add / drop filter, an optical filter having a multilayer film structure, a grating filter, and a photonic. Since it is composed of any one of the crystal filters, there is an advantage that the output signal light from the optical signal amplifying element and the ambient light are efficiently separated and simultaneously output to the optical fiber or the waveguide, respectively.

  Further, according to the optical signal amplification three-terminal device 10 utilizing the negative feedback optical amplification effect of the present embodiment, the optical coupler 16 is composed of an optical add / drop element, so that it is input to the optical signal amplification element 18. There is an advantage that the optical signals of the first wavelength λ1 and the second wavelength λ2 are efficiently combined.

  Further, according to the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of the present embodiment, the electrical input signal SE1 is an audio input signal that represents sound in an analog manner. In this way, the speaker can be driven by an electrical output signal having a sufficiently high S / N ratio and an input / output amplitude amplification ratio and a sufficiently low error rate, so that high sound quality can be obtained.

  Further, according to the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of the present embodiment, the electro / optical conversion element 14 is a semiconductor laser whose output light is controlled in response to the electric input signal SE1. Or since it is a light emitting diode, an electrical input signal can be easily converted into an optical signal.

  Further, the optical signal amplification three-terminal device 10 using the negative feedback optical amplification effect of the present embodiment is used as an audio preamplifier or an audio effector, so there is no noise, a sense of depth, and a high quality with a reverberation. Sound can be obtained.

  As mentioned above, although one Example of this invention was described based on drawing, this invention is applied also in another aspect.

  For example, the wavelength selection element 20 of the above-described embodiment selects an optical signal having the first wavelength λ1 from the light output from the optical amplification element 18, and outputs the optical signal having the first wavelength λ1 as the optical output signal SP3. Even if the optical signal having the second wavelength λ2 is selected from the light output from the optical amplifying element 18, the optical signal having the second wavelength λ2 is output as the optical output signal SP3. Good. Of the light output from the optical amplifying element 18, the optical signal of the first wavelength λ1 and the optical signal of the second wavelength λ2 are merely in phase with each other, so that they can be interchanged depending on the application. Because there is.

  In addition, the optical amplifying element 18 provided in the optical signal amplifying three-terminal device 10 of the above-described embodiment is composed of one stage of optical amplifying element, but includes two stages of optical amplifying elements. Alternatively, it may be provided with three or more optical amplification elements.

  Further, the optical amplifying element 18 provided in the optical signal amplifying three-terminal device 10 of the above-described embodiment is an element (EDFA) made of an optical fiber containing an erbium element, but praseodymium is added as a rare earth element ( It may be a doped optical fiber amplifier.

  The above description is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit of the present invention.

It is a block diagram explaining the structure of the optical signal amplification 3 terminal apparatus of one Example of this invention. It is a time chart explaining the action | operation of the optical signal amplification 3 terminal apparatus of the Example of FIG. The characteristic which shows the relationship between the frequency of an electrical input signal, and modulation | alteration degree ratio when the optical signal amplification element with which the optical signal amplification 3 terminal apparatus of the Example of FIG. 1 was comprised with the erbium doped optical fiber It is a figure, Comprising: It is a figure shown by contrast with the case where there exists an inversion electrical input signal, and the case where it does not exist. FIG. 1 shows the relationship between the frequency of an electrical input signal and the input / output voltage ratio when the optical signal amplification element provided in the optical signal amplification three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber. It is a characteristic figure, Comprising: It is a figure shown by contrast with the case where there exists an inversion electrical input signal, and the case where it does not exist. 1 between the frequency of the electric input signal and the S / N ratio of the electric output signal when the optical signal amplifying element provided in the optical signal amplifying three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber. FIG. 6 is a characteristic diagram showing the relationship between the case where there is an inverted electric input signal and the case where there is no inverted electric input signal. 1 between the frequency of the electric input signal and the bit error rate BER of the electric output signal when the optical signal amplifying element provided in the optical signal amplifying three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber. It is a characteristic view which shows the relationship. In order to show the operation when the optical signal amplification element provided in the optical signal amplification three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber, an electrical input signal of 100 Hz, an optical input signal, an inverted electrical It is a figure which shows the waveform of an input signal, an inversion light input signal, and an electrical output signal, respectively. FIG. 1 is a characteristic diagram showing the relationship between the magnitude of an inverted electrical input signal and the modulation ratio when the optical signal amplification element provided in the optical signal amplification three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber. It is. The frequency of the electrical input signal and the electrical output signal when the optical signal amplification element provided in the optical signal amplification three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber based on fluoride. It is a characteristic figure which shows the relationship with an input / output voltage ratio, Comprising: It is a figure shown by contrast about the case where an inversion electric input signal is 0V, 1V, and 5V. The frequency of the electrical input signal and the electrical output signal when the optical signal amplification element provided in the optical signal amplification three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber based on fluoride. It is a characteristic view showing the relationship with the S / N ratio, and is a diagram showing the case where the inverted electrical input signal is 0V, 1V, 5V in comparison. The optical signal amplifying element provided in the optical signal amplifying three-terminal device of the embodiment of FIG. 1 is composed of an erbium-doped optical fiber having a fluoride as a base material, and the erbium-doped silicate glass is used for light. It is a characteristic view which shows the relationship between the frequency of an electrical input signal, and the distortion factor of an electrical output signal when a fiber is comprised. FIG. 2 is a characteristic diagram showing the relationship between the frequency of an electrical input signal and the input / output voltage ratio when the optical signal amplification element provided in the optical signal amplification three-terminal device of the embodiment of FIG. 1 is constituted by a semiconductor optical amplification element. FIG. 6 is a diagram showing a comparison between a case where an inverted electrical input signal is present and a case where an inverted electrical input signal is absent. FIG. 3 is a characteristic diagram showing the relationship between the frequency of an electrical input signal and the bit error rate BER when the optical signal amplification element provided in the optical signal amplification three-terminal device of the embodiment of FIG. 1 is configured by a semiconductor optical amplification element. FIG. 6 is a diagram showing a comparison between a case where an inverted electrical input signal is present and a case where an inverted electrical input signal is absent. 1 is a characteristic diagram showing the relationship between the frequency of an electrical input signal and the input / output voltage ratio when the optical signal amplifying element provided in the optical signal amplifying three-terminal device of the embodiment of FIG. FIG. 5 is a diagram showing a comparison with another type of optical signal amplifying element. It is a figure explaining the state by which the optical signal amplification 3 terminal apparatus of the Example of FIG. 1 was integrated in the audio circuit.

Explanation of symbols

10: optical signal amplification three-terminal device 12: signal inversion element 14: electro / optical conversion element 16: optical coupler 18: optical signal amplification element 20: wavelength selection element 22: optical / electric conversion element

Claims (13)

An optical signal amplification three-terminal device using a negative feedback optical amplification effect for converting an electric input signal into an optical signal and amplifying the signal;
A signal inverting element for inverting and outputting the electrical input signal;
Electric / optical conversion for converting the electrical input signal into an optical input signal having a first wavelength and converting the inverted electrical input signal output from the signal inverting element into an inverted optical input signal having a second wavelength different from the first wavelength. Elements,
An optical signal amplifying element having a negative feedback optical amplification effect;
An optical coupler that combines the optical input signal and the inverted optical input signal that are respectively output from the electric / optical conversion element and inputs the combined optical signal to the optical signal amplification element;
A wavelength selection element that selects the optical signal of the first wavelength or the second wavelength from the light output from the optical signal amplification element;
An optical signal amplification three-terminal device comprising: 2. The optical signal amplification three-terminal device according to claim 1, wherein the optical signal amplification element comprises an optical fiber doped with a rare earth element. 3. The optical signal amplification three-terminal device according to claim 2, wherein the optical fiber is doped with erbium. 4. The optical signal amplification three-terminal device according to claim 2, wherein the optical fiber base material is made of fluoride. 2. The optical signal amplification three-terminal device according to claim 1, wherein the optical signal amplification element is a semiconductor optical signal amplification element having an active layer made of a pn junction. 6. The optical signal amplification three-terminal device according to claim 5, wherein the active layer of the semiconductor optical signal amplifying element is formed of any one of a quantum well, a strained superlattice, and a quantum dot. 7. The optical signal amplification three-terminal device according to claim 1, wherein the wavelength selection element is formed of any one of an optical add / drop filter, an optical filter having a multilayer film structure, a grating filter, and a photonic crystal filter. . 8. The optical signal amplification three-terminal device according to claim 1, wherein the optical coupler is composed of an optical add / drop element. 9. The optical signal amplification three-terminal device according to claim 1, wherein the electrical input signal is an audio input signal that represents sound in an analog manner. 10. The optical signal amplification three-terminal device according to claim 1, wherein the electro / optical conversion element is a semiconductor laser or a light emitting diode whose output light is controlled in response to the electric input signal. The optical signal amplification three-terminal device according to any one of claims 1 to 10, which is used as an audio preamplifier or an audio effector. 12. The optical signal amplifier 3 according to claim 1, further comprising an optical / electric conversion element that converts an optical signal selected by the wavelength selection element into an electrical signal and outputs the electrical signal as an electrical output signal. Terminal device. The optical signal amplification three-terminal device according to claim 12, wherein the electrical output signal output from the optical / electrical conversion element has a high degree of modulation with respect to the electrical input signal.

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