CN1710760A - Distributed feedback single longitudinal mode optical fiber laser - Google Patents

Abstract

A distributed feedback single longitudinal mode fiber laser includes a DFB fiber laser, which is constructed as follows: the two ends of the DFB fiber laser fiber are fixed on a thin metal plate with ultraviolet silica gel, the metal plate is placed on a semiconductor ceramic plate, there is a layer of thermal conductive silica gel between the metal plate and the semiconductor ceramic plate, the semiconductor ceramic plate is placed on a heat sink, the metal plate is connected to the control electrode of a temperature control power supply through a thermistor, the two ends of the semiconductor ceramic plate are respectively connected to the two electrodes of the temperature control power supply through two wires, the above-mentioned units, except the temperature control power supply, are all encapsulated in a heat insulation cover, one end of the DFB fiber laser fiber extends out of the heat insulation cover and is connected to a laser pump source through a wavelength division multiplexer, and the third end of the wavelength division multiplexer constitutes the output end of the laser of the present invention through an optical fiber isolator.

Description

Distributed Feedback Single Longitudinal Mode Fiber Laser

technical field

The invention relates to a fiber laser, in particular to a stable operation tunable Distributed feedback of phase shift—distributed feedback (DFB) single longitudinal mode fiber laser. The laser can be used as the main oscillator in the front-end system of the inertial confinement nuclear fusion laser driver, and can be used in optical fiber sensors and spectral analysis devices.

Background technique

Write a grating on a Yb-doped fiber (ytterbium) to obtain a Yb-doped fiber DFB laser. Generated at the geometric center of the uniformly written DFB laser phase shift, a single longitudinal mode fiber laser is produced. The wavelength of such lasers can be determined by:

λ=2nΛ

Among them, λ is the operating wavelength of the DFB laser, n is the effective refractive index of the fiber, and ∧ is the grating period. Therefore, when the value of the grating period ∧ is changed, the operating wavelength of the DFB laser can be changed. The value of the grating period ∧ can be changed by changing the temperature and applying different sizes of pulling force.

statement of problem

There are two existing tuning methods:

1. Directly change the temperature of the DFB laser to obtain the tuning output of the DFB laser.

2. The laser operating wavelength of the DFB laser can be tuned by changing the pulling force applied to the DFB laser by mechanical means.

In the first method, the wavelength tuning range is less than 1 nm even with a temperature variation range of 100 degrees Celsius. And with a temperature range of 100 degrees Celsius, if it is necessary to work stably in a low temperature area (less than -30 degrees Celsius) for a long time, the requirements for the temperature adjustment and control system are very high, and the operating cost is high. However, the operating temperature higher than 50 degrees Celsius will have adverse effects on the characteristics of the DFB laser and the performance of other surrounding devices.

The second method uses a mechanical device to tune the laser operating wavelength of the DFB laser by changing the magnitude of the pulling force applied to the DFB laser. Therefore, changes in the ambient temperature will cause the shift of the wavelength operating point, and it is not easy to make the system work stably at a certain level for a long time. wavelength.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide a distributed feedback single longitudinal mode fiber laser, which not only needs to obtain a wide wavelength tuning range, but also overcomes the drift of the wavelength operating point caused by environmental temperature changes, so that the working The wavelength is more stable.

Technical scheme of the present invention is as follows:

A distributed feedback single longitudinal mode fiber laser, including a DFB fiber laser, which is composed of: the two ends of the DFB fiber laser fiber are fixed on a thin metal plate with ultraviolet silica gel, and the metal plate is placed on a semiconductor ceramic sheet , there is a layer of heat-conducting silica gel between the metal plate and the semiconductor ceramic sheet, the semiconductor ceramic sheet is placed on a heat sink, the metal plate is connected to the control pole of the temperature control power supply through a thermistor, and the semiconductor The two ends of the ceramic sheet are respectively connected to the two poles of the temperature control power supply through two wires. The above-mentioned units, except the temperature control power supply, are all packaged in a heat shield. The output end of the DFB fiber laser fiber Extending out of the heat shield, one end of the DFB fiber laser fiber protrudes out of the heat shield, and is connected to a laser pump source through a wavelength division multiplexer. The third end of the division multiplexer constitutes the output end of the laser of the present invention through a fiber isolator.

The DFB fiber laser is an ytterbium-doped DFB fiber laser or an erbium-doped DFB fiber laser.

The metal plate is an aluminum plate.

The advantage of the laser of the present invention is:

(1) Since the coefficient of thermal expansion of the aluminum block (26×10 ^-6 /k) is much larger than that of the silica fiber (5.5×10 ^-7 k), the above structure is adopted, compared with the method of directly adjusting the temperature of the DFB , so that the laser tunable wavelength range is greatly increased (from 1nm to 3.4nm), but the temperature range to be changed is very small.

(2) Compared with the direct mechanical stretching method, the electric temperature control adjustment method has higher precision, stability, reliability and good repeatability.

(3) The temperature control and the heat shield cooperate to greatly reduce the influence of the system on the environment, and the wavelength stability of the single longitudinal mode of the laser is good.

Description of drawings

Fig. 1 is the structural representation of embodiment 1 of the present invention

In the picture:

1—radiating plate, 2—semiconductor ceramic sheet, 3—thermal silica gel, 4—thermistor, 5—strip metal plate, 6—Yb-doped DFB fiber laser, 7, 8—ultraviolet glue, 9—temperature control power supply, 10, 11—conductive wire, 12—optical fiber isolator, 14—semiconductor laser.

Detailed ways

Please refer to Fig. 1, Fig. 1 is the structural representation of embodiment 1 of the present invention, as seen from the figure, the composition of distributed feedback single longitudinal mode fiber laser of the present invention is: the two ends of a Yb-doped DFB fiber laser 6 optical fibers (long 10cm) are used The ultraviolet silica gel 7, 8 is fixed on a thin aluminum plate 5, and the aluminum plate 5 is placed on the semiconductor ceramic sheet 2, and there is a layer of heat-conducting silica gel 3 between the aluminum plate 5 and the semiconductor ceramic sheet 2, and the semiconductor ceramic sheet 2 is placed on a On the cooling plate 1, the aluminum plate 5 is connected to the control pole of the temperature control power supply 9 through a thermistor 4, and the two ends of the semiconductor ceramic sheet 2 are connected to the temperature control power supply through two wires 10 and 11 respectively. The two electrodes of 9 are connected to each other. Above-mentioned units, except the temperature control power supply 9, are all encapsulated in a heat shield, and one end of the YbDFB-doped fiber laser 6 optical fiber stretches out of the heat shield. A wavelength division multiplexer 13 is connected with a semiconductor laser 14, and the third end of the wavelength division multiplexer 13 forms an output end of the laser of the present invention through a fiber isolator 12.

By changing the driving power of the semiconductor ceramic sheet—the electric power of the temperature control power supply 9, the temperature of the semiconductor ceramic sheet 2 and the aluminum plate 5 can be changed. When the length of the aluminum plate 5 changes with temperature, the Yb-doped optical fiber DFB structure fixed on it The period ∧ also changes, thus achieving the purpose of tuning the operating wavelength of the laser. In addition, 2-8 units in the device are packaged in a heat shield, so the core components of the device of the present invention are greatly reduced by the environment, and the single longitudinal mode of the laser has good wavelength stability.

It has been proven through trials that the distributed feedback single longitudinal mode fiber laser of the present invention can be tuned and operated from 1052.4nm to 1055.8nm. The wavelength tuning range is 3.4nm, converted to a frequency range of 1020GHz. The tuning accuracy measured with a fixed F-P scanning interferometer is about 100MHz. When the wavelength of the above laser is tuned to any value in the above range, then use the fixed F-P scanning interferometer to observe the stability of the operating wavelength of the laser. The spectral resolution of the fixed F-P interferometer used is about 30MHz. Through visual inspection, there is no observation From the drift phenomenon of the single longitudinal mode laser interference ring, it can be inferred that the single longitudinal mode frequency stability drift fluctuation of the laser of the present invention is less than 30MHz. The maximum output power of the laser is 30mW, and the output power fluctuation is less than 5‰.

The difference between embodiment 2 and embodiment 1 is that the DFB fiber laser 6 is an erbium-doped DFB fiber laser. Its technical effect is the same as above, its application range is wider, and it has more practical value.

Claims (3)

1. A distributed feedback single longitudinal mode fiber laser, comprising a DFB fiber laser (6), characterized in that the two ends of the DFB fiber laser (6) optical fiber are fixed on a thin metal with ultraviolet silica gel (7,8). plate (5), the metal plate (5) is placed on the semiconductor ceramic sheet (2), between the metal plate (5) and the semiconductor ceramic sheet (2) is a layer of heat-conducting silica gel (3), the semiconductor ceramic Sheet (2) is placed on the radiator plate (1) again, and described metal sheet (5) is connected with the control electrode of temperature control power supply (9) through a thermistor (4), and described semiconductor ceramic sheet (2 ) are respectively connected to the two electrodes of the temperature control power supply (9) through two wires (10,11), and the above-mentioned units, except the temperature control power supply (9), are all encapsulated in a heat shield , the output end of an optical fiber of the DFB fiber laser (6) stretches out from the outside of the heat shield, and is connected to a laser pumping source (14) through a wavelength division multiplexer (13), the described The third end of the wavelength division multiplexer (13) constitutes the output end of the laser of the present invention through a fiber isolator (12). 2. The distributed feedback single longitudinal mode fiber laser according to claim 1, characterized in that the DFB fiber laser (6) is an ytterbium-doped DFB fiber laser or an erbium-doped DFB fiber laser. 3. The distributed feedback single longitudinal mode fiber laser according to claim 1, characterized in that the metal plate (5) is an aluminum plate.

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