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Abstract We report a self-induced spatially-coherent dot array consisting of fourteen units of vertical-cavity surface-emitting modes that exhibit spatially uniform spectra. A 47.5 µm total beam width and 0.5° narrow emission are achieved using an oblong cavity enclosed with a flat top mirror, cylindrically curved bottom mirror, and side facet. Notably, terminating the side of the cavity with a perpendicular facet enhances the horizontal propagation, which couples with the vertical resonance in each dot, similar to the case of master lasers in injection-locked lasers that delocalize the modes. Conventional semiconductor lasers, edge-emitting lasers, and vertical-cavity surface-emitting lasers have a Fabry–Pérot cavity; furthermore, emission and resonance are in identical directions, limiting the beam width to micrometers. Though the present structure has the same scheme of propagation, the right-angled facet synchronizes the modes and drastically expands the beam width.

Here the authors demonstrate chip-scale high-peak-power lasers by vertical integration of semiconductor and solid state laser gain mediums to reach the same maturity level as existing semiconductor lasers, which are suitable for miniaturization and cost-effective mass production.

We report a narrow divergence angle in a blue gallium-nitride-based visible vertical-cavity surface-emitting laser (GaN-VCSEL) with a curved mirror. This device exhibited continuous-wave operation at a wavelength of 447.9 nm. The full-width at half-maximum divergence angle of the 8 μm-aperture VCSEL was 3.9° when the device was operated at a current of 1.2 × Ith, where Ith is the threshold current. In this type of cavity, the radius of curvature (ROC) of the curved mirror determines the near-field pattern (NPF) and far-field pattern (FFP). The authors fabricated devices having ROC up to 988 μm, which is more than 10 times greater than the ROC of the mirror used in the previously reported structures, allowing this narrow emission. The I–L characteristics showed that the Ith value increased with increasing ROC. The present study investigates the mechanism behind this tendency in detail.

We investigated the spectral and temporal characteristics of blue-violetfemtosecond optical pulses generated by a passively mode-locked GaInN laser diode ina dispersion-compensated external cavity. The output optical pulses at 400 nm wereanalyzed in detail by intensity auto- and cross-correlation measurements using secondharmonic generation on the surface of a β-BaB2O4 crystal. The obtained results clarifiedwavelength-dependent chirp characteristics of the optical pulses. The analysis suggestedthat a large frequency shift due to saturation in the saturable absorber and gain sectionsplayed an important role in the generation of femtosecond optical pulses.