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VCSELs have recently received increasing attention from engineers and scientists. The progress of the research on GaN‐based VCSELs that allowed blue and green emissions are often one of the main topics discussed in this field. Combining these lasers with existing red VCSELs realized a full‐color light source with superior characteristics of VCSELs, such as small power consumption, circular beam profiles, and arraying ability. These features should be suitable for displays, for example, AR displays. In this report, a brief review of the recent progress regarding these VCSELs and their future applications is provided.

This study obtained highly uniform and efficient GaN-based vertical-cavity surface-emitting lasers with curved mirrors from a single wafer. The average threshold current (Ith) and the optical output power (Pmax) of 14 chips measured up to 7.0 mA were 0.64 mA and 4.5 mW, respectively. The standard deviations of Ithand Pmaxwere 6.7% and 5.1%, respectively. Additionally, the best chip showed maximum values of wall plug efficiency and output power of 13.4% and 7.6 mW, respectively, at 5.2 mA and 12.8 mA operating currents.

A single cavity filtering mirror with a highly varying reflectivity spectrum was used to demonstrate a single longitudinal mode operation for a VCSEL with a ∼25 μm cavity length. The 443.5 nm lasing peak had an SMSR of 42 dB at 9 mA, 70 kA cm−2. Increasing the number of DBR pairs between the VCSEL and filtering mirror cavity reduced the simulated optical standing wave in the mirror cavity by 57% and experimentally gave a 42% increase in the slope efficiency to achieve 2.56 mW at 7 mA from a device with a 4 μm aperture with a single longitudinal mode.

We present optical pulse generation with 100 W peak power, 3 ps temporal duration, and 1 GHz repetition from a GaInN master oscillator power amplifier (MOPA). An external cavity GaInN laser diode is passively mode-locked to generate 4 W peak power optical pulses as a master oscillator, and a semiconductor optical amplifier (SOA) effectively amplified these to a high peak power of more than 100 W. Two major factors that contributed to effective amplification of optical pulses were the generation of clean optical pulses without sub-pulse components by the GaInN mode-locked laser diode and suppression of amplified spontaneous emission in the SOA. This novel high-peak-power pulse source is used to induce multi-photon absorption to create sub-micrometer recording marks in a bulk plastic recording media. The realization of an all-semiconductor pulse source is a significant breakthrough towards a practical 3D optical data storage system.

We demonstrate a room-temperature continuous-wave operation of green vertical-cavity surface-emitting laser (VCSEL) with a 20 ?m long cavity possessing a dielectric curved mirror formed over a {20?21} semi-polar gallium nitride substrate. The emission wavelength and the threshold current were 515 nm and 1.8 mA, respectively. We also confirmed that white light is generated by overlaying three prime colors of light, i.e. red, blue and green, emitted only from VCSEL.

We report single transverse mode operation of a blue GaN-based vertical-cavity surface-emitting laser (GaN-VCSEL) with a monolithically incorporated curved mirror. For a device with a 4 ?m current aperture diameter and a curved mirror with a radius of curvature (ROC) of 51 ?m, single transverse mode operation was confirmed up to an output power of 3.2 mW under continuous wave operation at 20 °C. For a device with a smaller ROC of 31 ?m, multi transverse mode operation was confirmed, indicating that the transverse mode can be controlled by the cavity design of such GaN-VCSELs.

The continuous wave operation of a gallium-nitride-based vertical-cavity surface-emitting laser (GaN-based VCSEL) that uses boron ion implantation for lateral current confinement and a curved mirror for lateral optical confinement was investigated. The threshold current was 0.25 mA (Jth= 3.5 kA cm?2) for a 3 ?m diameter current aperture at room temperature and the lasing wavelength was 445.3 nm. This is the lowest threshold current recorded for a GaN-based VCSEL. This result is considered to be a milestone for the further miniaturization of GaN-based VCSELs by the implementation of lateral optical confinement due to the incorporation of a curved mirror.

Femtosecond optical pulses with a duration of 200 fs were generated using a GaInN bisectional laser diode passively mode-locked in a dispersion-compensated external cavity with spectral filtering performed outside the cavity. The fact that the femtosecond pulses were obtained with a negative intracavity group-velocity dispersion and a saturable absorber recovery time of about 15 ps indicates that the mechanism involved was soliton mode-locking. The spectro-temporal investigation of the output pulses directly emitted after the mode-locked laser diode revealed that the spectral broadening was due to self-phase modulation in the gain section.

We have generated picosecond optical pulses with a peak power greater than 300 W at 1 GHz repetition at a blue-violet wavelength using a GaInN-based master oscillator power amplifier. The optical pulses were generated by a mode-locked laser diode incorporating the flared waveguide structure for the increased active region volume to obtain higher output power. The pulses were effectively amplified by the semiconductor optical amplifier with reduced optical confinement factor to high peak power.