Study On Vertical Cavity Surface Emission Lasers Based On Sub-wavelength Grating

In 1977,Iga of Tokyo Institute of Technology in Japan first proposed the concept of Vertical Cavity Surface Emission Lasers(VCSEL).Because its optical resonant cavity is perpendicular to the semiconductor chip substrate,it can achieve laser emission on the chip surface,and has the advantages of low cost,narrow line width,easy high frequency modulation,dynamic single mode operation.It is widely used,especially in the fields of military communications,atomic gyroscopes,and miniature atomic clocks.VCSEL has become a hot spot in international research.This thesis mainly studies the vertical cavity surface emitting laser based on the sub-wavelength grating to realize the convergence,deflection and polarization stabilization of the laser lasing beam.A 894 nm high temperature vertical cavity surface emitting laser with polarization stabilization function and 850 nm single-mode vertical cavity surface emitting laser with beam converging function are obtained through design and simulation.The main contents of the thesis are as follows:1.Designed and simulated 850 nm non-periodic sub-wavelength grating with beam convergence function,894 nm non-periodic sub-wavelength grating with beam deflection function and 894 nm periodic sub-wavelength grating with polarization stabilization function.Based on the wave front phase adjustment principle of the sub-wavelength grating and strict coupled wave theory,the mathematical data of the grating is calculated using MATLAB mathematical tools,and the non-periodic sub-wavelength grating is designed and simulated using the COMSOL finite element simulation software.It realizes that the beam with an operating wavelength of 850 nm is incident on a one-dimensional strip sub-wavelength grating,the transmittance is 97%,the focal length is 15.1?m,and the extinction ratio is 19.6d B;a beam with a working wavelength of 894 nm is incident on the sub-wavelength grating,and the beam is obtained by numerical calculation.The actual deflection angle is 28.75°,the error is smaller than the ideal 30°,the transmittance reaches95.42%.When TM and TE polarized light with a wavelength of 894 nm are incident on a one-dimensional periodic sub-wavelength grating,respectively,TM and TE polarization are obtained.The transmittance of light is 97.814% and 1.017%;the reflectance is 1.302%and 98.628%.After calculation,the polarization extinction ratio is 18.7d B.2.A 894 nm high temperature vertical cavity surface emitting laser with polarization stabilization was designed and simulated.By improving the gain cavity mode mismatch and the size and shape of the oxidized aperture,the device's output power is stabilized at about 2m W under the operating environment of 20-90?;the laser beam of the device is realized using a non-periodic sub-wavelength grating Divided into left and right beams according to the polarization state,the extinction ratio of the output port of the device is>30d B.The problems of red shift of laser wavelength,increase of threshold current,and mode instability caused by self-heating effect or temperature rise in the working environment are improved,and the device has a stable polarization output.3.Design and simulate a 850 nm single-mode vertical cavity surface emitting laser with beam convergence.By etching a sub-wavelength grating with a diameter of 3?m and a thickness of ?/4 on the top of the device,the high-order mode of the device is suppressed to ensure the output of a single mode;The non-periodic sub-wavelength grating is used to realize the beam convergence function,which solves the problem of a relatively large divergence angle of the outgoing beam caused by the small circular aperture of the device.At the same time,the problem of lateral mode competition due to excessive oxidation aperture or light exit aperture of the device is improved,so that the device can meet the requirements of low divergence angle under the premise of single-mode operation.