Technology Research On Near Infrared Semiconductor Laser With Built-in Grating

It is one of the powerful methods to improve the performance of the semiconductor laser by using the optical modulation characteristics of the grating to achieve laser wavelength stability,high beam quality and polarization output,which has obtained the extensive attention of the researchers.In this paper,we studied the embedded grating technology of near infrared laser diode,the optical properties of different grating and the method of grating design and the fabrication process of the grating.Based on the rigorous coupled wave theory,the equivalent medium theory,the optical wave transmission theory and the coupled mode theory,the transmission performance of the subwavelength grating,we studied the reflection performance of the high refractive index difference grating and the coupling performance of the second order Bragg grating.The effects of the grating period,ridge height and duty ratio on the performance of the grating were analyzed.For the different applications of grating in semiconductor laser,we designed the 976 nm sub wavelength antireflective grating,1550 nm high refractive index difference high reflectivity grating and 976 nm two order Prague grating.The photoresist coating process and laser interferometric lithography process were studied especially.Through the test and analysis,the preparation method of different photoresist thickness and the best optimal lithography pattern with 900 nm,450nm,400 nm and 300 nm cycles were obtained respectively.By improving the experiment and adding the surface hard mask technology,we successfully prepared the 300 nm period grating with good quality.