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A mid-infrared vertical external cavity surface emitting laser (VECSEL) based on undoped PbS is described herein. A 200 nm-thick PbS active layer embedded between PbSrS cladding layers forms a double heterostructure. The layers are grown on a lattice and thermal expansion mismatched Si-substrate. The substrate is placed onto a flat bottom Bragg mirror again grown on a Si substrate, and the VECSEL is completed with a curved top mirror. Pumping is done optically with a 1.55 μm laser diode. This leads to an extremely simple modular fabrication process. Lasing wavelengths range from 3–3.8 μm at 100–260 K heat sink temperature. The lowest threshold power is ∼210 mWp and highest output power is ∼250 mWp. The influence of the different recombination mechanism as well as free carrier absorption on the threshold power is modeled.

We demonstrate a miniaturized blue laser (5 × 12 × 1.5 mm 3 ) using second harmonic generation (SHG), which consists of a quasi-phase-matched (QPM)-SHG waveguide device on an x-cut Mg-doped LiNbO 3 substrate and a tunable distributed-Bragg-reflector (DBR) laser diode. By using the QPM-SHG waveguide device on an x-cut substrate, efficient optical coupling was realized without a half-wave plate, and the maximum coupling efficiency of 75% was achieved. The blue light power of 2 mW was generated for the fundamental coupling power of 20 mW, which agreed with a conversion efficiency of 10%. The mechanical stability of the planar-type butt-coupled SHG blue laser was examined, where the coupling efficiency was maintained constantly under the change of module temperature and the temperature cycle test from 10 to 60 • C. We succeeded in downsizing the SHG blue laser to 0.1 cm 3 , which is sufficiently small for its application to optical disk systems.

By using air‐cooled RGB lasers including a compact and efficient green SHG laser and new illumination optics for speckle noise reduction, we developed advanced laser projection engine. A prototype of laser rear projection display with low electric consumption (about 50W) for light sources and wide color gamut (137%NTSC) was realized.

A compact and high power green-light source has been developed in diode-pumped solid-state laser based on periodically poled Mg:LiNbO3 (PPMgLN). Optimization of the PPMgLN length in Nd:YVO4 intracvity can achieve wide operation temperature range over 30 °C with maintaining high conversion efficiency. Based on this result, we demonstrated 3 cm3 laser module which generated continuous-wave 0.7-W green light with wall-plug efficiency as high as 11.8%.