Design And Numerical Simulation On Dual-wavelength Oscillating Of A Laser Diode With An External Cavity

A dual-wavelength oscillating semiconductor laser subjected to external optical feedback is investigated. The external cavity laser is actually a common semiconductor laser with a optical feedback component beyond the laser's interior cavity. And the dual-wavelength laser can emit two color optical waves simultaneously. Using a external cavity laser to generate two color optical waves is the aim to study in this paper which makes the preparation for continuous terahertz (THz) wave generation using a dual-wavelength laser.Firstly, the progress and foreground of external cavity laser and terahertz technology are reviewed, and the task and significance of this paper is introduced. Then the basic theory about semiconductor laser subjected to external optical feedback is described, mainly including the mode dynamics. To get dual-wavelength tunable laser, a Fourier-transform external cavity with a V-shaped-golden feedback mirror (the reflectivity is up to 99%) is designed which can realize two color laser selective feedback and tuning. After the optical calculation, we get the relationship between the mirror's adjustable distance Ax and the different frequency betweendual wavelength △λ: △λ = . In practical applications, we can slightlychange the cavity configure to get other kinds of Fourier-transform external cavity. The mode characters of semiconductor laser subjected to external optical feedback is numerically simulated and get the result that the number of stable modes in semiconductor laser increases as the feedback rate of equivalent cavity k increases and the total number retains odd 2n+1, n=0,1,2…. The original single mode would transforms to multimode even chaotic. In dual-wavelength laser simulation, whenthe feedback rates of each color are equal, there'll be two wavelength output with identical intensity, but when the rates are different, their output intensity will be obviously different, even there is only one color laser output. From the above, we can see that there is competition between the two color lasers. At last, we demonstrate experimental study on the characteristics of grating-tuned external cavity semiconductor laser subjected to single wave feedback.This paper refers to external cavity design and numerical simulation for dual-wavelength oscillating external cavity semiconductor laser and the experiment on grating-tuned external cavity semiconductor laser. These results can offer some guidance for further study in two color lasers and terahertz generation.