The 850-nm oxide-confined vertical-cavity surface-emitting lasers with petal-shape holey structures are presented. An area-weighted average refractive index model is given to analyse their effective index profiles, and the graded index distribution in the holey region is demonstrated. The index step between the optical aperture and the holey region is obtained which is related merely to the etching depth. Four types of holey vertical-cavity surface-emitting lasers with different parameters are fabricated as well as the conventional oxide-confined vertical-cavity surface-emitting laser. Compared with the conventional oxide-confined vertical-cavity surface-emitting laser without etched holes, the holey vertical-cavity surface-emitting laser possesses an improved beam quality due to its graded index distribution, but has a lower output power, higher threshold current and lower slope efficiency. With the hole number increased, the holey vertical-cavity surface-emitting laser can realize the single-mode operation throughout the entire current range, and reduces the beam divergence further. The loss mechanism is used to explain the single-mode characteristic, and the reduced beam divergence is attributed to the shallow etching. High coupling efficiency of 86% to a multi-mode fibre is achieved for the single-mode device in the experiment.
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 wave- guide is designed, and fabricated through BCB bonding technology and standard i-line photolithography. Com- pared 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 magnetic plasmon （MP） modes in the metal-dielectric-metal nanosandwich structure are investigated nu- merically, and the principle of energy resonance in such a resonator is proposed. An equivalent inductance capacitance circuit analysis method is proposed and the results are in agreement with the numerical simulations. Based on the MP resonance in such a structure, a nanosandwich chain waveguide is designed. Gold and silver are chosen as the metal materials. The power transmission e^ciency of the nanosandwieh waveguide can be as high as 0.546 in a specific nanosandwich unit cell, even when the metal absorption loss is large, which is the perspective of the new waveguides and lasers based on MP modes.
GaInAs/AlGaAs comprehensive-strained three-quantum-well lasers with asymmetric waveguide are designed and optimized.With this design,the optical field in the transverse direction is extended,and a semiconductor laser with large spot is obtained.For a 300-μm cavity length and 100-μm aperture device under continuous wave（CW） operation,the measured vertical and horizontal far-field divergence angles are 12.2？ and 3.0？,respectively.The slope efficiency is 0.44 W/A and the lasing wavelength is 917 nm.The equivalent transverse spot size is 3 μm for the fundamental transverse mode,which is a sufficiently large value for the purpose of coupling and manipulation of light.
