Polarization-stabilized tunable VCSEL with internal-cavity sub-wavelength grating

In this paper, a tunable VCSEL with internal-cavity sub-wavelength grating structure at 850nm was demonstrated. Utilizing the birefringence and anti-reflection characteristics of the sub-wavelength grating, the tunable VCSEL with wide wavelength tuning range and stable TE polarization mode was achieved. The relationships between the parameters of sub-wavelength grating and the transmittance/effective index of two polarization modes were analyzed. The tuning efficiency, polarization mode and wavelength tuning range of the tunable VCSEL with internal-cavity sub-wavelength structure were studied. Simultaneously, the MEMS cantilever structure with 'bowknot' shape on the end of the cantilever was designed, which can effectively avoid the concentration of stress distribution and reduce the maximum stress. The results show that the wavelength tuning range is 22.7nm, the peak output power is 1.6mW at 20°C, and the polarization suppression ratio is more than 20dB.