JPS59131909A - Optical recording head - Google Patents

Abstract

PURPOSE:To scan in a high speed with small-sized constitution by providing light shield plates at the projection terminal of an incident optical waveguide and the incidence terminal of a coupled optical waveguide and a DC voltage electrode on the side of the incident optical waveguide, and obtaining convergency with a variable refractive index near the projection terminal of the coupled optical waveguide. CONSTITUTION:The coupled waveguide 5 has a uniform refractive index distribution up to a length l, and the refractive index decreases at the ratio of the square of the distance from a center axis to obtain convergence at a projection part. When light is incident to the incident optical waveguide 4 while no voltage is applied to an electrode 2, the propagated light is in a state (a) with a complete coupling length L, and all coupled with and propagated to the waveguide 5 and projected with intensity P0 to be convegted at a distance (f). When the light is incident while a DC voltage E0 is applied to the electrode 2, the refractive index in the waveguide 4 varies by electrooptic effect to disconnect the waveguides 4 and 5 from each other, and the projection intensity is 0 as shown by (b), so that no light is projected from the waveguide 5. The projection intensity is controlled by the DC voltage to realize high-speed operation as an optical shutter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical recording head, and more particularly to an electro-optic optical recording head that uses a directional coupler type optical modulator and records on a recording medium using an external electrical signal.

Conventionally, optical scanning recording devices have used a laser beam as a recording light source.The light beam is polarized by a rotating polygon mirror, focused by an f-theta lens, and converted into linear bright spot motion. It was then recorded in a record book. However, since each member is independent, high precision is required for assembly and adjustment of the device, and each twisted member must be arranged at a certain distance between the optical paths, resulting in a large device. .

In contrast, the present applicant has filed an application for a new optical recording head (Japanese Patent Application No. 117969/1989) that solves the above-mentioned drawbacks, and the contents include a directional coupler type optical modulator array and an imaging lens system. The objective was to obtain a compact device that could replace the conventional large-sized optical scanning recording device that required precise adjustment.

However, since the directional coupler type optical modulator array and the imaging lens system are each independent, they have the disadvantage of requiring optical axis adjustment. Therefore, an object of the present invention is to solve the above-mentioned drawbacks by improving the contents of the optical recording head (Japanese Patent Application No. 57-117964), and to provide an optical recording head that is small and capable of high-speed scanning. .

According to the present invention, there is provided a directional coupler type optical modulator including an incident optical waveguide and a coupling optical waveguide into which light from a recording light source is incident, and an output end of the input optical waveguide and an input end of the coupling optical waveguide are shielded from light. A light beam comprising a continuous light plate, a direct current coining plate 7 which is provided on the side of the incident light waveguide and which controls the light flux from the recording light source; a +1 electrode and a switch element that supplies an external electric signal to the application electrode. In the recording head, the output vicinity of the coupling optical waveguide of the directional coupler type optical modulator is formed into a focusing optical waveguide whose refractive index decreases according to the distance from the central axis of the coupling optical waveguide. You will get the head.

Further, according to the present invention, there is provided a directional coupler type optical modulator array in which a plurality of directional coupler type optical modulators are arranged in parallel, and an external electric signal is applied to each application electrode of the plurality of modulators. Claim (1) characterized in that it includes a switch element array constituted by a plurality of switch elements supplied.
The optical recording head described in Section 2 is obtained.

Furthermore, according to the present invention, the coupling optical waveguide is a convergent optical waveguide whose refractive index decreases in accordance with the square of the distance from the central axis in the vicinity of the output thereof. An optical recording head is obtained.

Furthermore, according to the present invention, the waveguide spacing between the incident optical waveguide and the coupling waveguide is set at a constant interval in the fully coupled length part, and gradually increases in other parts. The optical recording head of the term is reduced by 4%.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an optical recording head which is an embodiment of the present invention.

In FIG. 1, one embodiment of the present invention is a directional coupler type optical modulator having an input optical waveguide 4 through which a light beam from a recording light source is incident, and a coupling optical waveguide 5 through which a light beam is irradiated onto a photosensitive recording medium. 1, and a switch element 3 that controls the optical modulator 1.
and controlling whether or not to emit a light beam from the directional coupler type optical modulator by an external electric signal from a DC power source EO applied to a switch element 3, and using the presence or absence of the light beam as information. It is the head.

Directional coupler type optical modulator used in this example (Related reference material GaAselectro-optic dir
ectio--nal coupler 5w1th,
Applied Phy, Lett.

5-Vol 127. Na4 Aug 1975) 1 is a structure in which an input optical waveguide 4 and a coupling optical waveguide 5 are formed adjacent to each other using a transparent rectangular parallelepiped substrate made of electro-optic crystal such as lithiniopate. A light shielding plate 6 made of electrical insulator is provided on the input side of each
, 6' are provided, and furthermore, DC voltage applying electrodes 2, 2' are provided on the upper surface of the transparent substrate above the incident optical waveguide 4.

In the coupling optical waveguide 5, the refractive index near the output end is ≠ the central axis.
≧Convergent optical waveguide Kg that decreases according to the square of the distance between
The output light is flattened onto the recording medium without passing through the imaging lens.

The incident optical waveguide 4 is provided with a DC voltage applying electrode 2 on the upper surface of a transparent substrate for supplying a DC voltage Eo.
It is configured to apply the DC power source EO through the switch element 3.

Directional coupler type optical modulator 1 Length L of the waveguide spacing between the incident optical waveguide 4 and the coupling waveguide 5 at which all the optical energy in the incident optical waveguide is transferred to the coupling optical waveguide when no DC voltage is applied. In other words, perfect coupling 6- is constant within the length, and the distance (spacing) is gradually increased in parts larger than this perfect coupling length, so that coupling with the input waveguide does not occur at the output part of the coupling waveguide. It looks like this. In addition, although the coupling waveguide has a uniform refractive index distribution up to the length e, the output part of the coupling optical waveguide becomes a focusing waveguide whose refractive index decreases according to the square of the distance from the central axis. Finally, the light emitted from the coupled optical waveguide is focused. The output end of the input waveguide 4 has a light shielding plate 6 made of an electrical insulator, and the input end of the coupling waveguide 5 has a light shielding plate 6' made of an electrical insulator. Efficiency
It is designed to emit radiation. FIG. 2 shows the relationship between the applied voltage of the directional coupler type optical modulator and the output light intensity.

Here, we will discuss the operation of the present directional coupler type optical modulator 1 in a second manner.
This will be explained with reference to the figures. Now, when the light beam 7 is incident on the incident optical waveguide 4 in a state where the DC voltage EO is not applied to the electrode 2, the optical energy propagating within the incident optical waveguide 4 will change as shown in the graph of FIG. The state shown in A is reached, and all of the optical energy incident on the incident optical waveguide 4 is coupled to the coupling waveguide 5, propagates within the coupling waveguide 5, and is focused at the output portion to output a light beam 8 with an intensity PO.

The light beam 8 is focused at a distance f from the output end of the coupling waveguide. The reason why the distance between the input waveguide 4 and the coupling waveguide 50 gradually increases with respect to the output end due to the complete coupling length in ζ is that the refractive index of the coupling waveguide is aligned with the central axis at the output part. Since the propagation speed of the light changes to decrease according to the square of the distance from This is to prevent migration.

Next, the voltage EO of the DC power supply is applied to the electrode 2 through the switch element 3.
When the light beam 7 enters the incident optical waveguide 4 in a state where it is applied through As a result, the light intensity of the light beam emitted from the coupling optical waveguide 5 becomes 0 as shown in the graph of FIG. 2, and no light beam is emitted from the coupling optical waveguide 5.

In this way, the directional coupler type optical modulator can control the intensity of the output light beam 8 coming out of the coupled optical waveguide 5 by applying a DC voltage. Further, this directional coupler type optical modulator operates as an optical shutter and is capable of high-speed operation of several hundred MHz or more.

Regarding the above directional coupler type modulator, Appli
ed Phy, LetL Vo127 Na4 Au
g 1975 rGaAa electro-opt
ic directional coupler aw
ithJK is described in detail.

Next, another embodiment of the present invention using a plurality of directional coupler type optical modulators according to one embodiment of the present invention is shown in FIG. In FIG. 3, this embodiment includes a directional coupler type optical modulator array 10 in which several directional coupler type optical modulators 1 shown in FIG. - Switch element array 11 that can be turned off and optical modulator array 1
It includes a recording light source 9 such as a fluorescent lamp that is supplied to the input optical waveguide 5 and a recording medium 12 that is exposed to light from the output optical waveguide 5.

9 unidirectional coupler type optical modulator array 10 includes each modulator (1-1
1-5) are arranged at a sufficiently larger interval than the interval between the input optical waveguide 4 and the coupling optical waveguide 5. The light beams 7 (7-1 to 7-5) emitted from the light source 9 enter the respective incident optical waveguides 4 (4-1 to 4-5)K.

This directional coupler type optical modulator has a voltage application electrode 2 and a switch element array]1 each switch element (11-1 to 1l).
Since the DC power supply EO is connected through the switch 11-5), the application of DC voltage is controlled by opening and closing each switch element of the switch element array 11 using an external electric signal.

The individual directional coupler type optical modulators in the optical modulator array 10 are outputted to the coupling optical waveguide 5 when each switch element (11-1 to 1l-5) is off, and the light beam 8 is output from the coupling optical waveguide 5. (R-1 to 8-5), and when each switch element (11-1 to 1l-5) is on, light is cut off.

Therefore, the optical modulator array 10 receives 1tlF of light by controlling the switching elements. Next scan can be done. The light beam 8 from the output optical waveguide 5 has a distance f from the output end since the output 10-opposite end of the coupling waveguide 5 is a focusing waveguide.
The light is focused on the recording medium 12 placed at the
2, the presence or absence of light is recorded as information.

As explained above, the present invention enables the scanning of a recording light source to be performed by controlling the application and cut-off of DC voltage to a plurality of directional coupler type optical modulators, so that a compact optical recording head can be constructed. This allows for easy assembly and adjustment without the need for an external imaging lens.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a directional coupler type optical modulator which is an embodiment of the present invention, and FIG. 2 shows the relationship between the output light intensity of the directional coupler type optical modulator of FIG. 1 and the applied voltage. The figure shown in FIG. 3 is a perspective view showing another embodiment of the present invention. 1... Directional coupler type optical modulator, 2 (2-1~
2-10')... Electrode, 3... Switch element, 4... Incident optical waveguide, 5...
Output optical waveguide, 6.6'... Light shielding plate, 7 (7-
1 to 7-5), 8 (8-1 to 8-5)... Luminous flux, 9 Old... Light source, 10 Old... Directional coupler type optical modulator array, 11... Mark/switch element array, 12...
...Record. 1 time early and 2 times. t red 0 electric L

Claims (4)

[Claims] (1) A directional coupler type optical modulator consisting of an input optical waveguide and a coupling optical waveguide into which light from a recording light source is incident, and a light shielding plate that blocks light from the output end of the input optical waveguide and the input end of the coupling optical waveguide. and an optical recording head, which is provided on the incident light waveguide side and includes an electrode for applying a DC voltage for controlling the light flux from the recording light source, and a switch element for supplying an external electric signal to the applying electrode trap. An optical recording head in which the vicinity of the output of the coupling optical waveguide of a directional coupler type optical modulator is made into a converging optical waveguide whose refractive index decreases according to the distance from the central axis of the coupling optical waveguide. . (2) A directional device in which a plurality of directional coupler type optical modulators are arranged in parallel, a combiner type optical modulator array, and an external and a switch element array configured of a plurality of switch elements that supply electrical signals.
) The optical recording head described in item 2. (3) The output vicinity of the coupled optical waveguide is 2 times the distance from the central axis.
The optical recording head according to claim 1, wherein the optical recording head is a converging optical waveguide whose refractive index decreases according to the power of the optical recording head. (4) Waveguide spacing between the incident optical waveguide and the feeding waveguide
The optical recording head according to claim 1, wherein the fully coupled length portions are arranged at regular intervals, and the other portions are gradually thickened.