We propose a polarization-insensitive and broadband subwavelength grating reflector based on a multilayer structure.The reflector has an overlapped high reflectivity(>99.5%) bandwidth of 248 nm between the TE and the TM polarizations,which is much higher than the previously reported results.We believe this subwavelength grating reflector can be applied to unpolarized devices.
A novel hybrid Ⅲ–Ⅴ/silicon deformed micro-disk single-mode laser connecting to a Si output waveguide is designed, and fabricated through BCB bonding technology and standard i-line photolithography. Compared to a traditional circular micro-disk in multi-longitudinal-mode operation, unidirectional emission and single longitudinal-mode output from a Si waveguide are realized. In the experiments, an output power of 0.31 mW and a side-mode suppression ratio of 27 dB in the continuous-wave regime are obtained.
We report a novel lateral cavity surface emitting laser based on sub-wavelength high-index-contrast grating with in-plane resonance and surface-normal emission. The device is fabricated on a simple commercial wafer without the distributed Bragg reflector and it needs no wafer bonding. It exhibits a side mode suppression ratio of 23.0 d B and a high output power of 5.32 m W at 1552.44 nm. The specific single mode lasing agrees well with the band edge mode calculation of the grating. In 3D simulation, we observe obvious light output from the grating.
The output performance of a 980-nm broad-area vertical-cavity surface-emitting laser(VCSEL) is improved by optimizing the p-electrode diameter in this study.Based on a three-dimensional finite-element method,the current density distribution within the active region of the VCSEL is optimized through the appropriate adjustment of the p-electrode diameter,and uniform current-density distribution is achieved.Then,the effects of this optimization are studied experimentally.The L-I-V characteristics under different temperatures of the VCSELs with different p-electrode diameters are investigated,and better temperature stability is demonstrated in the VCSEL with an optimized p-electrode diameter.The far-field measurements show that with an injected current of 2 A,the far-field divergence angle of the VCSEL with an optimized p-electrode diameter is 9°,which is much lower than the far-field angle of the VCSEL without this optimization.Also the VCSEL with an optimized p-electrode diameter shows a better near-field distribution.
