Study Of Fiber Bragg Grating External Cavity Dual-Wavelength Semiconductor Laser Technology

In absolute-distance interference measurement, the shorter the synthetic wavelength is, the higher the measurement accuracy becomes, so investigating the dual-frequency laser technique is of great significance. The gain linewidth of semiconductor laser (LD) is very wide, and fiber Bragg grating (FBG) external cavity semiconductor laser (FBG-LD) has many advantages such as narrow linewidth, high stable frequency and high side mode suppression ratio (SMSR), etc. so FBG-LD has attractive in the field of dual-frequency laser with large frequency-difference.In the thesis, four parts are mainly included as follows. First, based on equivalent cavity model of FBG-LD, the principle of single mode selection is analyzed, and it is pointed out that the most important selection mode reason is the decrease of loss coefficient, which acts not only in the strong feedback FBG-LD, but also in the week feedback FBG-LD. Second, a scheme of FBG-LD is presented to realizing dual-wavelength simultaneous oscillation output. When the FBG is pressed transversely along the fiber profile the birefringence appears in FBG, two Bragg reflective peaks are formed. Using this FBG as the LD external feedback element, dual-wavelength simultaneous oscillation output is accomplished in the FBG-LD. In the thesis a Fabry-Perot cavity semiconductor laser with a FC-PC plug is jointed with a fiber including a FBG to form a week feedback FBG-LD, and the feasibility of the scheme is analyzed theoretically, the indicate shows that FBG-LD run at single mode output when the FBG is not pressed, and dual-wavelength simultaneous oscillation may realize by transversely pressing the FBG. Third, the couple technique of fiber to LD and single mode output of FBG-LD are studied. Single mode output of the week feedback FBG-LD is realized experimentally. The results show the reflection rate of FBG and the temperature has prominent influence on the week feedback FBG-LD. Forth, dual-wavelength output of FBG-LD is also studied experimentally, and dual-wavelength simultaneous oscillation of FBG-LD is carried out at 1537nm wavelength on the condition of transversely pressing the fiber profile, the result shows the difference of the two wavelengths is dependent on the applied force. Such a result has been analyzed theoretically.