The Holographic Grating Fabrication Of High-power And Wavelength-stabilized Semiconductor Laser

Semiconductor lasers have many excellent features, for example, small size, high efficiency and so on. They are widely used in laser communications, laser pumping, and many other fields. However, with the increasingly widespread application of semiconductor lasers, the problem of the quality of low stability of the lasting wavelength begins to emerge in the researchers’ view. To solve the above problem, DFB lasers, DBR lasers appear. Considering the advantages of small size and wavelength stability of the DFB lasers and the crucial role in laser pumping 808 nm semiconductor laser plays, the built-in second-order Bragg grating of the high-power 808 nm DFB lasers was mainly designed and prepared in this paper.Through theoretical analysis of high-power 808 nmDFB lasers, the parameters such as the photoelectric conversion efficiency, output width, temperature drift coefficient and so on were combined with coupled-mode theory and transfer matrix method. Then the relevant parameters of the grating such as the diffraction order number, period, duty cycle, depth and length were initially identified. Subsequently, the holography exposure and the wet etching processes were utilized to prepare the built-in InGaP/GaAsP/InGaP grating of the high-power 808 nm DFB-LD. The SEM and AFM were used to analyze the prepared Bragg grating. Under optimum conditions, the surface of the prepared grating was uniform and its shape was close to sinusoidal. The second order diffraction grating had a period of 242.8nm, a duty cycle of 0.25, a depth of 40 nm and a length of 3mm. The DFB laser’s optical power was 2W, cavity length was 3mm, injecting width was 200μm, the rate of lasting output wavelength along with temperature variation was 0.075nm/K, the threshold current was 0.52 A, the slope efficiency was 0.67W/A.