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.

The control of the photonic crystal waveguide over the beam profile of vertical-cavity surface-emitting lasers is investigated. The symmetric slab waveguide model is adopted to analyze the control parameters of the beam profile in the photonic-crystal vertical-cavity surface-emitting laser （PC-VCSEL）. The filling factor （the ratio of the hole diameter to the lattice constant） and the etching depth control the divergence angle of the PC-VCSEL, and the low filling factor and the shallow etching depth are beneficial to achieve the low-divergence-angle beam. Two types of PC-VCSELs with different filling factors and etching depths are designed and fabricated. The experimental results show that the device with a lower filling factor and a shallower etching depth has a lower divergence angle, which agrees well with the theoretical predictions.

The magnetic plasmon (MP) modes in metal-dielectric-metal nanosandwich structures are investigated numerically using finite-difference time-domain method. We demonstrate the law of the quality factor in this kind of resonator. According to the MP modes in the nanosandwich structures, we design a series of resonators of this kind in order to investigate how to tune the resonante frequencies of MP modes through tuning the geometrical parameters and the dielectric layer refractive index of resonators, and the obtained result is well consonant with our analysis by the equivalent inductance capacitance circuit. We also investigate the electromagnetic energy confinement of the nanosandwich resonators, and analyse the Q factors of these structures from thermal and radiant points of view, which will guide one in designing new waveguides and lasers based on MP modes.

We demonstrate a novel oxide confined GaAs-based photonic crystal vertical cavity surface emitting laser (PC-VCSEL) operating at a wavelength of 850 nm based on coherent coupling. A ring-shaped light-emitting aperture is added to the conventional PC-VCSEL, and coherent coupling is achieved between the central defect aperture and the ring-shaped light-emitting aperture. Measurements show that under the continuous-wave (CW) injected current of 20 mA, a high power of 2 mW is obtained, and the side mode suppression ratio (SMSR) is larger than 20 dB. The average divergence angle is 4.2° at the current level of 20 mA. Compared with the results ever reported, the divergence angle is reduced.

Phase-locked oxide-confined ring-defect photonic crystal vertical-cavity surface-emitting laser is presented. The coupled-mode theory is employed to illustrate the two supermodes of the device, in-phase and out-of-phase supermode. Experimental results verify the two supermodes by the characteristics of the spectra and the far field patterns. At the lower current, only the out-of-phase supermode is excited, whereas under the higher current, the in-phase supermode also appears at the shorter wavelength range. In addition, the measured spectral separation between the two supermodes agrees well with the theoretical result.

The three-dimensional (3D) plane wave expansion method with supercell approximation has been employed to investigate in detail the band structure of the two-dimensional photonic crystal (PhC) surface-emitting laser with square lattice. The symmetric point band structure has been calculated to obtain the optimized structures of PhC surface-emitting lasers. There exists a range of parameter pairs, including periods and area-filling factors of the PhC, which can create an in-plane stop band at the high frequency side of the monopole mode at the second order of the Γ-point (Γ2- 1) in each structure. This in-plane stop band isolates Γ2- 1 from the unwanted band edge modes, inhibits the spontaneous emission at the high frequency side of Γ2- 1, makes the device achieve single band edge mode lasing oscillation and improves the performance of the PhC surface-emitting laser. The resonant spectra, quality factors and output efficiencies have been calculated by the 3D finite-difference time-domain method to verify the band optimization, which provides important guidelines for device design and fabrication.

The slow light effect in a photonic crystal waveguide is investigated theoretically and experimentally. Theoretical calculation indicates that there is a slow light region for the even mode, from which the resonance and lasing in a microcavity would benefit. A photonic crystal waveguide microlaser is fabricated, which is related to the group velocity of c/120.6.

Photonic crystals possessing large gap–midgap ratios are designed using the improved Bisection-Particle Swarm Optimization (BPSO) algorithm and plane-wave expansion method. The optimal gap–midgap ratios of three kinds of photonic crystals, such as ring rods, square rods connected by veins, and rotating square rods, are calculated, and the corresponding geometry parameters are also represented. Compared with the traditional dimension-by-dimension scanning method, the improved BPSO algorithm greatly reduces the computation time, and its accuracy is controllable.

Inspired by the idea of the stero-coupling, we propose a new sandwich-like photonic crystal microcavity which is composed of double layer photonic crystal slabs H1 (DLPCS-H1) cavity with an air layer in between. We calculate the electromagnetic field distribution and the quality factor of the dipole mode by the three-dimensional finite-difference time-domain method and the Pade approximation method. Through carefully analyzing the effect of the air layer height on the quality factor of the dipole mode, we obtain an optimized DLPCS-H1 cavity in which the height of intermediate air layer is about 0.5a (a is the lattice constant, a = 420 nm). In this cavity, the quality factor of the dipole mode is 4 times as large as that of the conventional single layer photonic crystal slab H1 cavity. Furthermore, we study the three-layer photonic crystal slabs H1 cavity, and the quality factor of its dipole mode is increased over 7 times.

Generally, dipole mode is a doubly degenerate mode. Theoretical calculations have indicated that the single dipole mode of two-dimensional photonic crystal single point defect cavity shows high polarization property. We present a structure with elongated lattice, which only supports a single y-dipole mode. With this structure we can eliminate the degeneracy, control the lasing action of the cavity and demonstrate the high polarization property of the single dipole mode. In our experiment, the polarization extinction ratio of the y-dipole mode is as high as 51:1.

The dipole mode in triangular photonic crystal single defect cavity is degenerate. By deforming the lattice in photonic crystal we can obtain non-degenerate dipole modes. Lattice deforming in the whole photonic crystal destroys the characteristic of symmetry, so the distribution of the electromagnetic field is affected and the polarization of the electromagnetic field is also changed. Lattice deforming divides the degenerate dipole mode into the x-dipole mode and the y-dipole mode. It is found that the non-degenerate modes have better properties of polarization. So the high polarization and single dipole mode photonic crystal laser can be achieved by deforming the lattice of photonic crystal. In this paper, we simulated the cavity in photonic crystal slab and mainly calculated the quality factor of x-dipole mode under different deforming conditions and with different filling factors. The properties of polarization of x-dipole and y-dipole modes are also calculated. It is found that the ratio of intensities of Ex to Ey in x-dipole mode and that of Ey to Ex in y-dipole mode are 44 and 27, respectively.

The authors developed an inductively coupled plasma etching process for the fabrication of hole-type photonic crystals in InP. The etching was performed at 70°C using BCl3∕Cl2 chemistries. A high etch rate of 1.4μm∕min was obtained for 200nm diameter holes. The process also yields nearly cylindrical hole shape with a 10.8 aspect ratio and more than 85° straightness of the smooth sidewall. Surface-emitting photonic crystal laser and edge emitting one were demonstrated in the experiments.

Selectively oxidized ring crystal vertical cavity surface (RD-PCVCSEL) is demonstrated. The coherent coupling over the entire current range.

The invention discloses a photonic crystal thin plate type surface emitting annular beam laser. An active area of the laser comprises a photonic crystal structure and phase shift defects; and a photonic crystal structural unit in the active area is a round hole or an elliptical hole, and a lattice structure is stretched in certain degree, and is added with a phase shift defect with proper width. By utilizing the invention, the surface emitting laser with good polarization characteristics and prospected beams can be designed; and because of imperfect asymmetry when the photonic crystal structural unit is the elliptical hole, the optical-field distribution is changed, and further output light has good polarization characteristics.

Tunable edge emitting microlaser was realized with a line defect waveguide, in which the radii of holes adjacent to the defect were varied gradually. A tunable range of 57 nm was obtained experimentally.

Selectively oxidized ring defect photonic crystal vertical cavity surface emitting laser (RD-PCVCSEL) is first demonstrated. The device achieves coherent coupling over the entire continuous-wave current range.

A photonic crystal microlaser with elongate lattice was fabricated. Lasing action of single mode, y-dipole mode, was observed. With this mode, a high polarization extinction ratio of 51:1 was obtained.