CN203071398U - Liquid cooling narrow-spectrum high-power semiconductor laser stack - Google Patents

Abstract

The utility model relates to a liquid-refrigerated narrow-spectrum high-power semiconductor laser array, which is composed of a plurality of semiconductor laser bars stacked, and each bar is electrically connected in series, parallel or series-parallel combination; The liquid refrigeration circuit of the spectral high-power semiconductor laser stack is double-input and double-outlet, that is, one liquid inlet and one liquid outlet are set at both ends of the stack; among the bars forming the stack, the bar with the larger central wavelength Placed in the edge area of the stack, the bars with smaller central wavelengths are placed in the middle of the stack, so that the wavelength of the bars matches the temperature of the area. The utility model has a good spectral narrowing effect.

Description

Liquid-cooled Narrow Spectrum High Power Diode Laser Stack

technical field

The utility model belongs to the field of semiconductor laser manufacturing and relates to a stack of liquid-cooled narrow-spectrum high-power semiconductor lasers.

Background technique

With the continuous improvement of semiconductor laser output power, conversion efficiency and performance stability, high-power semiconductor lasers and their pumped solid-state lasers and fiber lasers are used in industry, advanced manufacturing, military, aerospace, medical, display, and entertainment. The application is becoming more and more high-level and high-precision, especially the high-efficiency automatic processing equipment formed by the combination of laser and computer numerical control technology, which has become a new driving force for the development of advanced manufacturing industry and has a huge market prospect. In order to increase the output power, multiple semiconductor laser bars are usually formed into an array, and the output power can reach several kilowatts to tens of thousands of watts. High-power semiconductor laser arrays are widely used in military defense and laser processing industries, and can also be used for pumping sources of solid-state lasers and fiber lasers, laser ignition, laser drilling, laser cutting, laser marking, and laser heat treatment. middle.

In many applications, semiconductor laser stacks, such as solid-state laser pumping, etc., require a narrow spectral width, but semiconductor laser stacks are composed of dozens of bars, and the spectral center wavelengths of each bar are inconsistent, so the final stack total The spectrum will be significantly broadened. Most of the existing research focuses on the spectral narrowing of semiconductor laser bars. In recent years, there have been some studies on the spectrum broadening mechanism of high-power semiconductor laser arrays at home and abroad, and the main reasons for the spectral broadening of semiconductor laser arrays are as follows: (Xingsheng Liu et al., Proceedings of 58th Electronic Components and Technology Conference (ECTC), pp. 1005-1010, 2008.)

(1) The composition or structure of each light-emitting point constituting the semiconductor laser array chip is not uniform, resulting in inconsistent wavelengths of each light-emitting point, thereby broadening the spectrum to a certain extent.

(2) The thermal effect of the high-power semiconductor laser causes the temperature of each light-emitting point to be inconsistent. According to the relationship between the wavelength of the semiconductor laser and the temperature change (the rate of wavelength change with temperature is usually 0.3-0.4nm/K), the central wavelength of each light-emitting point changes. This results in spectral broadening. Spectral broadening caused by thermal effects can be divided into two specific cases: (a) Ideally, when there is no cavity in the patch layer, a large amount of heat will be emitted during the operation of the high-power semiconductor laser array, and the light-emitting point and edge area of the semiconductor laser center area The temperature of the luminous point is inconsistent, resulting in different central wavelengths of each luminous point, and the spectrum is broadened; (b) In the packaging process of semiconductor lasers, there will inevitably be small holes in the patch layer. , Solder is prone to electromigration and electrothermal migration. Larger holes will significantly increase the local temperature near the luminous point of the semiconductor laser array, resulting in a red shift of the wavelength of the local luminous point, so the overall spectrum is broadened.

(3) Stress inhomogeneity generated during the packaging process leads to spectral broadening. In order to obtain higher conversion efficiency and higher continuous wave power, laser arrays usually use copper with good electrical and thermal conductivity as heat sinks. This inevitably creates stress on the laser diode array after packaging due to the mismatch in the coefficient of thermal expansion (CTE) of the semiconductor laser and the copper heat sink. The study found that the wavelength shift of the laser array due to stress inhomogeneity can reach 7meV, which eventually leads to spectral broadening of the laser array.

Due to the inconsistency of the spectra of the individual bars that make up the stack, the spectrum of the final stack will be significantly broadened. Therefore, in order to solve this problem, it is necessary to optimize the stack structure design to achieve the effect of preparing a narrow-spectrum semiconductor laser stack.

Utility model content

The purpose of the utility model is to provide a narrow-spectrum high-power semiconductor laser stack and a preparation method thereof, which have the advantages of simple method, convenient operation and low cost.

The purpose of this utility model is achieved through the following technical solutions:

A preparation method of a narrow-spectrum high-power semiconductor laser stack, comprising the following steps:

(1) According to the cooling method of the semiconductor laser stack, the simulation experiment is carried out on the semiconductor laser stack, and the temperature distribution of each bar area forming the stack is obtained;

(2) Measure the spectrum of each bar to obtain the center wavelength of each bar;

(3) Place the bar with a larger central wavelength in the area with a lower temperature simulated in step (1), and place the bar with a smaller central wavelength in an area with a higher temperature in the stack, so that the wavelength of the bar is the same as zone temperature matching;

(4) Assemble the array to achieve the consistent output of the wavelengths of the bars forming the array, which is a stack of high-power narrow-spectrum semiconductor lasers.

Based on the above principles, the following 1) and 2) two types of liquid-cooled semiconductor laser stacks are prepared. These two liquid-cooled semiconductor laser stacks are composed of multiple semiconductor laser bars stacked. Each bar is connected in series, in parallel or in series. Electrically connected in parallel combination;

1) The liquid refrigeration circuit is double-inlet and double-outlet, that is, one liquid inlet and one liquid outlet are set at both ends of the array. For this liquid-cooled semiconductor laser stack, it is obtained through experiments and simulations that the temperature distribution of each bar area forming the stack is symmetrical, the temperature in the middle of the stack is high, and the temperature at the edge areas on both sides of the stack is low. Place the bar with the larger central wavelength in the edge area of the stack, and the bar with the smaller central wavelength in the middle of the stack, so that the wavelength of the bar matches the temperature of the area, and the output spectrum of the assembled stack is narrow .

2) The liquid cooling channel is a unidirectional linear liquid-cooled semiconductor laser stack, that is, a liquid inlet is set at one end of the stack, and a liquid outlet is set at the other end. For this liquid-cooled semiconductor laser stack, it is obtained through experiments and simulations that the temperature of the area located at the liquid inlet is relatively low, and away from the liquid inlet, along the direction of liquid flow, the temperature of the corresponding bar area gradually increases; Each bar of the array is placed in sequence from the liquid inlet to the liquid outlet according to its central wavelength from large to small, that is, the bar with the larger central wavelength is placed near the liquid inlet of the array. In the region, the bar with a moderate center wavelength is set in the middle of the stack, and the bar with a smaller center wavelength is set in the area close to the liquid outlet, so that the wavelength of the bar matches the temperature of the area, and the output spectrum of the stack is narrow.

The utility model has the following beneficial effects:

1. The utility model has a good spectrum narrowing effect, and the spectral width of the stack of semiconductor lasers prepared by the method of the utility model can be reduced by about 30%.

2. The process of the utility model is relatively simple and the cost is low.

Description of drawings

Fig. 1 is a schematic diagram of the technical solution of the utility model;

Fig. 2 is a schematic structural diagram of a double-input double-outlet liquid refrigeration stack prepared according to the principle of the utility model;

Fig. 3 is the temperature distribution of the double-input and double-out semiconductor laser stack formed by 20 bars;

Fig. 4 is the 975nm peak power 5000W double-input double-out type semiconductor laser stacked spectrum test result that is made up of 20 bars prepared by the utility model;

Fig. 5 is a schematic diagram of the structure of a one-way linear liquid refrigeration stack prepared according to the principle of the utility model;

Fig. 6 is the temperature distribution of the unidirectional linear semiconductor laser stack formed by 60 bars;

Figure 7 shows the spectrum test results of the 808nm peak power 18kW through-type semiconductor laser stack composed of 60 bars.

Among the figure, 1 is a liquid inlet, 2 is a liquid outlet, and 3 is a semiconductor laser bar.

Detailed ways

Describe the technical scheme of the utility model in detail below in conjunction with accompanying drawing and embodiment:

As shown in Figure 1, according to the simulated temperature distribution, the wavelength distribution decreases with the increase of temperature.

First, the temperature distribution of each bar forming the stack is obtained through simulation and experiment; then the spectrum of each bar is measured to obtain the central wavelength of each bar; the central wavelength of the semiconductor laser bar will red-shift with the increase of temperature, When the temperature decreases, a blue shift occurs. When assembling the stack, the bars with a larger central wavelength are assembled in the lower temperature area (the stack edge area), and the bars with a smaller central wavelength are assembled in the higher temperature area (stack edge area). array middle area). Finally, the central wavelength of each bar tends to be consistent, so that the total spectral width is narrowed.

For the stack of double-input and double-out liquid-cooled semiconductor lasers, it is confirmed by experiments and simulations (as shown in Figure 3): the temperature distribution of each bar area forming the stack is symmetrical, the temperature in the middle of the stack is high, and the temperature of the stack is high. The temperature of the edge area on both sides is low. Place the bar with the larger central wavelength in the edge area of the stack, and the bar with the smaller central wavelength in the middle of the stack, so that the wavelength of the bar matches the temperature of the area, and the output spectrum of the assembled stack is narrow .

As shown in Figures 2 and 4, a 975nm peak power 5000W stacked semiconductor laser composed of 20 bars has been prepared by using the technical solution of the utility model. The spectral width is only 4.15nm.

For the unidirectional linear liquid-cooled semiconductor laser stack, it is confirmed by experiments and simulations (as shown in Figure 6): it is concluded that the temperature of the area located at the liquid inlet is lower, away from the liquid inlet, along the direction of liquid flow, the corresponding The temperature in the bar area increases gradually; therefore, the bar with the larger central wavelength is placed in the edge area of the stack entrance, and the bar with the smaller central wavelength is placed between the liquid outlets of the stack. Match the zone temperature.

As shown in Figures 5 and 7, an 808nm peak power 18kW stacked semiconductor laser composed of 60 bars was prepared by using the technical solution of the utility model. Its spectral full width at half maximum (FWHM) is 2.80nm, and its 90% energy width is 4.26nm.

It can be seen from the above embodiments that the utility model has a good effect of narrowing the spectrum and has strong practicability.

Claims (2)

1. A liquid-cooled narrow-spectrum high-power semiconductor laser array, which is composed of a plurality of semiconductor laser bars stacked, and each bar is electrically connected in series, parallel or a combination of series and parallel; the liquid-cooled narrow-spectrum high-power The liquid cooling circuit of the power semiconductor laser stack is double-input and double-out, that is, one liquid inlet and one liquid outlet are arranged at both ends of the stack; among the bars forming the stack, the bar with the larger central wavelength is placed in the In the edge area of the stack, the bars with smaller central wavelengths are placed in the middle of the stack, so that the wavelength of the bars matches the temperature of the area. 2. A liquid-cooled narrow-spectrum high-power semiconductor laser array, which is composed of a plurality of semiconductor laser bars stacked, and each bar is electrically connected in series, parallel or a combination of series and parallel; the liquid-cooled narrow-spectrum high-power The liquid cooling channel of the power semiconductor laser stack is a one-way linear liquid-cooled semiconductor laser stack, that is, a liquid inlet is set at one end of the stack, and a liquid outlet is set at the other end; The wavelengths are from large to small, and placed in each section from the liquid inlet to the liquid outlet in order to match the wavelength of the bar with the temperature of the area.

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