A semiconductor laser side-pumping module based on power feedback control

Abstract

This invention proposes a semiconductor laser side-pumping module based on power feedback control, comprising a semiconductor laser array, module optical elements, a status monitoring module, a current adjustment module, and a data storage, processing, and communication module. It employs multi-wavelength combined pumping to make the pump light spectrum wider than the laser crystal absorption peak, ensuring good matching with the laser crystal absorption peak even when the semiconductor laser array degrades. Fluorescence intensity monitoring is used, and the semiconductor laser array current is dynamically adjusted based on the monitored intensity and other module status monitoring data to maintain stable fluorescence intensity even when the semiconductor laser array conversion efficiency decreases. Simultaneously, various status monitoring data of the semiconductor laser pumping module are stored and compared with the semiconductor laser array lifetime curve to obtain remaining lifetime prediction data, which is then transmitted to the user terminal. This invention solves the technical problem of insufficient long-term stability of traditional pumping modules.

Description

Technical Field

[0001] This invention relates to the field of laser technology, specifically to a semiconductor laser pumping module, and more particularly to a semiconductor laser side-pumping module based on power feedback control. Background Technology

[0002] Laser diode (LD)-pumped all-solid-state lasers have important applications in the field of high-power lasers due to their advantages such as high output energy, uniform absorption, and compact structure. In side-pumped all-solid-state lasers, the pump module is used to generate pump light and inject it into the laser crystal. The pump module generally consists of a semiconductor laser and a laser crystal, and is used in applications such as the side-pumped laser module described in patent CN201310740784, the high average power diode-pumped laser module and its fabrication method described in CN201410007183, and the solid-state laser module pumped by a semiconductor laser in CN201410056127.

[0003] Semiconductor lasers are devices that use metal solder (such as indium or gold-tin) to bond the chip and heat sink together effectively. During operation, the device is subjected to high current and high temperature. After a period of time, due to electrical, thermal, mechanical stress, and material fatigue, the semiconductor laser will experience three types of degradation: bulk degradation (defects introduced during chip growth propagate and grow during long-term operation, eventually leading to device failure), surface degradation (optical absorption and oxidation heating on the chip cavity surface during operation, leading to cavity surface aging), and solder-related degradation (physical defects and microstructural changes caused by welding stress, electromigration, and electrothermal migration, leading to increased device stress and thermal resistance). These three types of degradation cause the output power of the semiconductor laser to gradually decrease under a constant driving current after a period of operation, thus exhibiting a "lifetime attribute." According to the requirements of GB / T 31358-2015 General Specification for Semiconductor Lasers, a semiconductor laser is considered to have failed when the output optical power or energy decays to less than 80% of its initial value. Based on actual research, the lifespan of pump modules using continuous-wave semiconductor lasers as pump sources in the industry is approximately several thousand hours; the lifespan of pump modules using quasi-continuous and pulsed semiconductor lasers as pump sources is approximately 10 hours. 8 The lifespan is on the order of sub-pulse. However, this lifespan specification is increasingly unable to meet the application requirements of various products. At the same time, the lifespan of the pump module is also difficult to predict, and the unpredictable end of its lifespan brings many adverse effects to production applications. Summary of the Invention

[0004] The purpose of this invention is to address the problems of insufficient long-term stability and unpredictable lifetime of existing pump modules by proposing a highly stable semiconductor side-pump module based on pump power feedback control. This solution, based on a traditional pump module, adds a short-wavelength semiconductor laser for wide-band matching, incorporates fluorescence intensity monitoring, and compensates the pump current based on fluorescence intensity to improve laser lifetime. Simultaneously, it provides a remaining lifetime prediction based on the trend of fluorescence intensity changes and the magnitude of the compensation current, and transmits the monitoring data and prediction data to the user.

[0005] The technical solution is as follows: First, the wavelength of the pump semiconductor laser chip is selected. Unlike the traditional 808nm single-wavelength matching, this solution adopts a short-wavelength matching scheme, that is, multiple wavelengths shorter than 808nm are combined to form a relatively flat composite spectrum with a center wavelength shorter than 808nm.

[0006] Secondly, a photodetector is placed between the emitting surfaces of adjacent pump semiconductor lasers to monitor the fluorescence intensity at 1064nm.

[0007] Third, based on the fluorescence intensity monitoring signal, parameters such as driving current and temperature are adjusted to ensure that the fluorescence intensity is relatively stable. When the luminous efficiency of the semiconductor laser decreases, the wavelength will shift to the longer wavelength direction when the current is increased to compensate. However, because the synthesized spectrum has a flat range, the fluorescence intensity can still be kept stable.

[0008] Fourth, based on changes in fluorescence intensity data, temperature and other state monitoring data, as well as the pre-tested semiconductor laser array lifetime curve, the operating time and the predicted remaining operating lifetime are obtained.

[0009] The advantages of this invention compared to the prior art are:

[0010] This design can maintain a relatively constant pump efficiency (i.e., it can match the crystal absorption line well) even when the wavelength of a single semiconductor laser chip redshifts (moves towards longer wavelengths) due to efficiency degradation after long-term operation, thereby extending the life of the pump module.

[0011] This design can monitor the fluorescence intensity at 1064nm, thereby dynamically adjusting the drive current and further extending the pump module's lifespan.

[0012] This design can predict the remaining lifespan of a module by using data and module monitoring data, thereby providing data support for users to determine reasonable usage strategies; Attached Figure Description

[0013] Figure 1 Schematic diagram of the pump module monitoring and feedback principle of the present invention

[0014] Figure 2 Schematic diagram of the pump module of the present invention

[0015] Figure 3 Traditional wavelength matching diagram

[0016] Figure 4 Multi-wavelength schematic diagram of the present invention

[0017] Figure 5 Schematic diagram of the synthesis wavelength matching of the present invention Implementation

[0018] Please refer to the instruction manual appendix. Figure 1 This invention provides a highly stable semiconductor side-pumping module based on pump power feedback control, including a laser crystal 1, a sleeve 2, a semiconductor laser array 3, a semiconductor laser heat sink 4, a photodetector 5, and a thermistor 6.

[0019] The type of laser crystal 1 is selected according to the required laser wavelength. For example, when a 1064nm laser is required, an Nd:YAG crystal can be selected, and when a 1053nm laser is required, an Nd:Glass crystal can be selected. The size of the laser crystal is selected according to the required output energy (or power).

[0020] Preferably, the sleeve 2 serves as a coolant channel and also needs to transmit pump light. The sleeve is selected based on the transmittance of the pump light. For example, quartz material can be selected for 80Xnm pump light. The sleeve size can be selected based on the pressure of the coolant.

[0021] Preferably, the semiconductor laser array 3 can be selectively designed according to the required laser output power. The wavelength of the semiconductor laser is selected and matched to create a relatively flat spectrum shorter than the crystal absorption peak, forming a laser array. For example, for Figure 3 The absorption spectrum of NdYAG crystal was obtained by using... Figure 4 The composite spectrum of a laser array with four wavelengths is as follows: Figure 5 As shown.

[0022] Preferably, the structure and material of the semiconductor laser heat sink 4 are designed and determined according to the heat generation and temperature control requirements of the semiconductor laser array.

[0023] Preferably, the photodetector 5 is a photodetector capable of detecting the wavelength of laser fluorescence. For example, for 1µm fluorescence, a Si photodiode detector can be selected.

[0024] Preferably, the thermistor 6 is used to detect the temperature near the laser array, and a platinum resistance detector can be selected for example.

[0025] The work process is as follows:

[0026] After the laser drive is powered on, the laser array 3 emits pump light, which passes through the sleeve 2 and enters the laser crystal 1. The crystal 1 generates fluorescence and illuminates the photodetector 5, causing the photodetector 5 to generate a certain current (or voltage) signal. At the same time, the thermistor 6 is used to detect the temperature of each array.

[0027] The pump module monitoring and feedback principle diagram of the present invention. Figure 2 The fluorescence intensity and temperature monitoring signals from the semiconductor laser array are transmitted to the status monitoring module, which then sends the monitoring data to the data storage, processing, and communication module as needed. After the pump module has been operating for a period of time, a decrease in its luminous efficiency or wavelength drift will cause a decrease in the fluorescence intensity produced by the crystal (or an increase in temperature). In this case, the status monitoring module will output a signal to the current regulation module to increase the injection current of the semiconductor laser array until the fluorescence intensity returns to its original value.

[0028] Meanwhile, the data storage, processing and communication module predicts the remaining lifespan of the module based on the collected data (including usage time, fluorescence intensity at different times, array temperature, current adjustment, etc.) and the laser array lifespan test curve, and sends the collected data and predicted data to the user.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that modifications can be made to these embodiments without departing from the principles and spirit of the invention, wherein the scope of protection of the invention is defined by the appended claims and their equivalents.

Claims

1. A power feedback control based semiconductor laser side-pumped module, comprising a semiconductor laser array, a module optical element, a state monitoring module, a current adjusting module, and a data storage processing communication module, characterized in that: The parameters of the semiconductor laser array are measured by the state monitoring module in real time, and are transmitted to the current adjusting module to adjust the power supply current of the semiconductor laser array in real time, so as to keep the light emitting power stable, and the data is sent to the data storage processing communication module to store and process the data, and then the processing result is sent to the user end; The overall spectrum of the semiconductor laser array is composed of multiple wavelengths, and is composed into a synthesized spectrum with a shorter central wavelength than the crystal absorption peak and a wider half-line width than the half-line width of a single chip; the central wavelength is shorter than 808nm; The array number of each wavelength point of the semiconductor laser array is similar to ensure that the intensity of each wavelength in the synthesized spectrum band is similar; The state monitoring module includes a photoelectric conversion chip for monitoring the fluorescence intensity generated by the laser crystal; Each photodetector is coated with a bandpass film of the required fluorescence waveband in front of or on the optical window, that is, only the fluorescence spectrum in the waveband wavelength range of ±1nm to ±20nm is allowed to enter the detector; the photodetector monitors the 1064nm fluorescence intensity; The data storage processing communication module stores and processes the running state data of the pump module, and estimates the remaining life according to the life prediction model; The data storage processing communication module can predict the remaining life of the pump module according to the pump module state monitoring data, the used time and the semiconductor laser life curve.

2. The semiconductor laser side-pumped module of claim 1, wherein: The current adjusting module can dynamically adjust the driving current or voltage of the semiconductor laser array according to the detected fluorescence intensity and other monitoring quantities of the pump module.

3. The semiconductor laser side-pumped module of claim 1, wherein: The current adjusting module is placed in the pump module or the driving power supply.

4. The semiconductor laser side-pumped module of claim 1, wherein: The data in the data storage processing communication module is stored on the built-in memory or transmitted to the external memory for storage. The data in the data storage processing communication module is stored on the built-in memory or transmitted to the external memory for storage.

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