High-power semiconductor lasers and high-power semiconductor laser pump lasers are used in civil fields such as material processing, laser marking, laser ranging, laser storage, laser display, laser lighting, laser medical treatment, as well as laser guidance, laser night vision, laser weapons, etc. It is widely used in the military field. How to realize the reliability and aging test evaluation of high-power semiconductor lasers, including the research on the pump source of the test system, has always been one of the hot topics in the subject and one of the important directions of international manufacturing research.
This program will introduce you a kilowatt-level semiconductor laser online testing and aging system, as well as an aging power supply compatible with CW and QCW. The product can collect the operating current, operating voltage, output optical power and other parameters of each aging device in real time, and monitor the heat sink temperature, cooling circulating water flow, and water temperature in real time. It has complete functions, high reliability, and excellent cost performance. The advantages of the laser can be popularized and used by the development and application units of high-power lasers.
A laser is mainly composed of a pump source, a gain medium, and a resonant cavity. Among them, the pump source is the light source of the laser, which provides energy for the laser. Lasers can be divided into four categories: electrical pumping, chemical pumping, optical pumping, and pneumatic pumping according to the pumping method, and can also be divided into liquid lasers, gas lasers, semiconductor lasers, and solid-state lasers according to the gain medium. Semiconductor lasers can be used not only as lasers alone, but also as pumping sources for fiber lasers and solid-state lasers.
The use of semiconductor lasers as solid-state laser pump sources can be compatible with the dual advantages of solid-state lasers and semiconductor lasers: high photoelectric conversion efficiency, high power, high stability, high reliability, long life, and small size. At present, semiconductor lasers have gradually replaced traditional lasers. Chlorine or argon lamps have become the main pump source of solid-state lasers, and are widely used in material processing, medical and scientific research fields.
The pump source is the source of laser energy. According to the law of energy conservation, the laser output laser energy beam needs to input energy when generating laser light. The pump source plays the role of energy excitation to the gain medium. When the laser is working, the pump source injects energy into the gain medium for excitation, and the electrons in the gain medium undergo an energy level transition after being excited by the energy, and transition from the ground state to the excited state. Since the excited state is an unstable state compared with the ground state, the electrons will spontaneously returns to the ground state and emits photons. Countless photons circulate in the two sections of the resonant cavity, reciprocate, and continuously superimpose, and finally output a high-energy laser beam with the same direction and frequency.
Laser working principle diagram
Laser Stimulated Emission Diagram
High-power semiconductor lasers are mainly divided into two structures: single tube and bar bar. The single tube structure mostly adopts the design of wide bar and large optical cavity, and increases the gain area to achieve high power output and reduce the catastrophic damage of the cavity surface; the bar bar structure It is a parallel linear array of multiple single-tube lasers, multiple lasers work at the same time, and then achieve high-power laser output through beam combining and other means.
Laser single tube and bar (linear array) structure
Edge emitting lasers and surface emitting lasers
Typical packages for semiconductor lasers
The role of packaging on semiconductor lasers: one is to establish a current loop, so that the chip can be stimulated by the current to generate light (stimulated radiation light amplification); the other is to dissipate heat, to solve the heat generated when the chip emits light; play a protective role.
Divided by function, there are two types of packaging for semiconductor lasers, one is protective shell packaging, and the other is chip packaging. Protective shell packaging mainly includes TO packaging and butterfly packaging. This packaging structure is to seal the COS with a protective cover made of metal or other materials. The advantages are: first, it will not be easily damaged, second, the probability of cavity surface contamination has been effectively reduced, and third, it is very portable. Chip packaging mainly includes F-Mount type packaging and C-Mount type packaging. Chip packaging is a method of directly soldering chips to heat sinks of different structures and materials. The function of the heat sink is mainly to dissipate the heat generated when the chip emits light, so as to ensure the continuous and stable operation of the chip.
The Importance and Current Situation of Diode Laser Chip Testing
The test of the laser chip is more complicated, involving the measurement of light and electricity, and the difference of packaging form should also be considered. Compared with traditional solid-state lasers or gas lasers at the same power level, high-power lasers have obvious advantages in terms of beam quality, work efficiency, structural volume, lifetime, and system maintenance. But at the same time, due to the high output power of a single chip and the large heat generated per unit area, if the heat dissipation technology is not done well, it will directly affect the output power, threshold current density, electro-optical conversion efficiency, differential molecular efficiency, polarization degree, etc. of the semiconductor laser. performance, and lead to a decrease in the lifetime and reliability of the semiconductor laser, and even damage the chip, which ultimately affects the reliability of the device. Therefore, it plays a very important role in the development of the laser industry chain to put the laser chip under extreme operating conditions such as high temperature and current for life and reliability experiments, eliminate early failure devices and detect failure factors before delivery. .
At present, high-power laser chips generally face various difficulties in the continuous output of high-current operation:
1. The measurement of laser chips generally depends on LIV data. The photoelectric parameters are greatly affected by heat. As the temperature rises, the threshold current of the chip increases;
2. The test results of the laser chip under DC and wide pulse are inaccurate; 3. The high-power laser has poor anti-surge impact ability, and it is required that the pulse current has no overshoot and the surge impact is small;
4. The fluctuation of the power supply will affect the life of the laser, and at the same time, it will cause unstable optical power and unstable heating of the device.
Innovative technology breakthrough, localized excellent cost-effective laser aging test system solution
Based on the technical development strength of the first domestically produced digital source measure unit (SMU), and the recognition and application research of products covering international communication and semiconductor head users for many years, Wuhan Precise needs to use narrow pulse and high current testing for kilowatt-level high-power semiconductor laser chips. And aging, serious chip heating and other problems, innovatively developed and launched a set of aging test system with good versatility, high power and circulating water cooling. The product has the characteristics of high current narrow pulse constant current, stable current, strong anti-interference ability, and has the functions of anti-overshoot, anti-recoil, anti-surge voltage regulation and constant current double protection circuit, etc. Aging testing provides a complete solution. An integrated test system that realizes multi-unit, high efficiency, automatic monitoring, and records and uploads test data.
Precise LDBIXX series multi-channel high-power laser aging system
After years of systematic research on digital source measure meters and a good foundation for product industrialization, the PRECISE pump laser aging test system adopts a newly developed and independently designed high-current pulse constant current source, which is compatible with CW mode (60A) and QCW mode (600A) ) supports four modes of DC constant current, DC sweep, pulsed DC, and pulse sweep. The driving power is controlled through the RS485 interface, the upper computer sets the output current, and can read the actual output value; in addition, multiple units can be connected in series and parallel in the form of one master and multiple slaves, the upper computer only needs to control the master, and the slave can realize synchronous output . Support linear scan, logarithmic scan and custom scan.
PRECISE HCPLOXX series high power laser test power supply