Study On The Semiconductor Light Source With The Stable Power And The Adjustable Frequency Linearly

In the past ten years, the development of semiconductor laser technology is rapidly, and its development is much faster than other laser technology. In practice, the current and temperature of equipment will have some small change. This kind of change will cause some changes of the output power of device, and it also affect the stability of the output power of equipment. High power density is a kind of characteristics of semiconductor laser. If the current and temperature can't keep constant, the optical power will appear a significant fluctuation, and it will lead to the power output of equipment cannot meet the requirement of stability. Therefore, it is necessary to ensure the stability of the device output power. First of all, we realize that the frequency of laser is tunable. Then, the electro-optic modulator and PID module are added with the basis of the frequency adjustable system, and it makes the output power of the light of the system more stable.The principle of linear frequency modulated laser ranging technique is introduced in this paper. According to the actual situation, we choose a preferred plan which is linear frequency modulation continuous wave laser ranging. FMCW ranging model is the theoretical basis of our experiment. According to the needs of the experiment, triangular wave frequency modulation was choose. By calculating the expression of beat frequency and the frequency of range resolution,this paper introduces the principle of saturated absorption spectrum of cesium atomic. According to the cesium atomic energy level structure, the energy level between the ground state 4 line and the ground state 3 line is 9.192KHz in hyperfine structure.By comparing the oscilloscope on line, the tuning bandwidth of triangle wave modulation signal can be calculated, and it is 22.5GHz.According to the needs of the experiment, laser frequency modulation system is build.The reference signal interference with the echo signal on the surface of the photoelectric detector, and the beat frequency signal can be got. The principle of it is same to the principle of michelson interferometer,but the frequency of the laser is linear modulation. By changing the distance of the measured target, the system can get the corresponding frequency. And this system can output linear light whose frequency can regulate. Due to the peak-to-peak value of the beat frequency in the frequency spectrum is higher and the spectrum of beat frequency is unstable. In order to further optimize the system, the electro-optic modulator and PID module are added to control the power of output light. Set up a light-path system whose power is stable and frequency is adjustable. Collecting and analyzing new beat frequency signal with the oscilloscope. At this time, the jitter of the beat frequency signal and the peak-to-peak value are smaller, and the signal becomes more smooth.