Temperature Effect towards DFB Laser Wavelength on Microwave Generation Based on Two Optical Wave Mixing

摘要

Semiconductor laser can be implemented in various fields, such as for telecommunication, radar, spectroscopy and sensor. Specialized for radar application, laser can be applied to generate microwave with heterodyne technique by mixing two laser sources. In this application, the quality of the laser wavelength stability is crucial in order to generate stability desired microwave source. In some studies it has been reported that the change of temperature causes the wavelength changes linearly. In our experiment, it is proven that the increase in temperature causes a shift in the peak wavelength toward the long wavelength laser typical of 0.094 nm/°C. Theoretically, it is shown that the wavelength shift caused by the thermal expansion on the laser grating period. In addition to the shift in wavelength, it is also shown that the increase in temperature causes a decrease in the optical power at the laser output. From the experiments of mixing two lasers that we have conducted, it was found that the tunability factor of laser beat frequency versus temperature is 10.35 GHz/°C. In this paper we show that the beat frequency of the result of mixing two laser diodes can be tuned by varying the temperature of one laser by varying Peltier temperature and laser injection current and let the other laser constant.