Two-wavelength Semiconductor Laser For Terahertz Generation

In this paper, a novel method to generate THz(Terahertz) electromagnetic wave by means of difference frequency technology in semiconductor laser is proposed.First of all, two modes working source is obtained by using fiber grating external cavity semiconductor laser. Instead of using added nonlinear crystal material, we make use of the nonlinearity of the semiconductor medium itself to mix that two waves, generating THz radiation by difference frequency effect. And that we design a experimental program to achieve.At the first of this paper, the unique property of THz wave, and its application prospects, and the research progress all over the world have been introduced, and give a brief of the work we did. Then put forward the design concept and its project model, and we simulated it using MATLAB. Starting with the fiber grating external cavity semiconductor laser, the analysis of the relationship between external cavity equivalent reflection efficiency and FBG reflectivity and the laser itself reflectivity of the cavity has been done. And the FBG reflectivity requirement to achieve the multiple wavelength output has been discussed. Simulating the mode spectrum of the two-wavelength semiconductor laser, and calculating the generation of THz wave. Through analyze the THz wave power spectrum, proved that the design is feasible. And studied the influence of wavelength and cavity length on output THz wave power, got the conclusion that the power increase as the wavelength increase, and other aspect its trend is the same as the two-wavelength semiconductor laser.While this approach obtained THz wave of low power (about dozens pw), it is a worthwhile research, a promising, low-cost terahertz waves source.