Visible Semiconductor Lasers Research Articles

A novel structure of visible semiconductor lasers

Terraced substrate inner current stripe lasers emitting in the range of 750–780 nm are developed with very simple fabrication processes. The lasers have good performance of cw room temperature, linear light-current output over 30 mW per facet and maintain stable fundamental transverse and longitudinal mode of 2–4 times current threshold. The current threshold of 25 mA under cw room temperature operation has been achieved.

Terraced substrate inner stripe visible semiconductor laser and its arrays

Lasers emitting in the range of 7500-7800 AA, which have average current thresholds of 30-40 mA and maintain single transverse mode operation up to 20 mW, are reported. Life tests show that the lasers have almost no threshold change after 3000 h of aging at 4-mW CW operation. The terraced substrate inner stripe laser arrays have clean single-lobe far-field patterns with full width at half power of 6 degrees in CW operation and 2.4 degrees in pulsed operation. >

Short wavelength operation in InGaAlP visible semiconductor lasers.

This paper reviews the recent results on the short wavelength (λ′650nm) operation of our InGaAIP visible semiconductor lasers. Theoretically, the InGaAlP visible lasers with an Al-containing active layer should have a highly doped p-type cladding layer in order to reduce the threshold current. The room-temperature cw operation of this material is expected down to the 600nm. We experimentally achieved the room-temperature cw operation to 636nm, using a heter-obarrier blocking structure.

Crystal structure of AlGaInP for visible semiconductor lasers and device characteristics.

The characteristic crystal structure (natural superlattice) of AlGaInP grown by metal-organic vapor phase epitaxy (MOVPE) for the use of visible semiconductor lasers, material depends on the growth conditions. This paper descibes the dependence of the crystal structure and the effect on the device characteristics and device designing. In this connection, short wavelength laser operation and a novel laser structure for high power operation are also described (briefly).

A new index-guided AlGaInP visible semiconductor laser with very small astigmatism

Summary form only given. The authors demonstrate a novel index-guided AlGaInP visible semiconductor laser with very small astigmatism. This laser, composed of a twin-groove ridge stripe structure, is formed by a two-step MOVPE process (metal-organic vapor phase epitaxy). After the AlGaInP (0.8 mu m)/GaInP (0.8 mu m) double heterostructure is grown on an n-GaAs substrate, a 3.5- mu m-wide ridge stripe is formed by etching the p-AlGaInP cladding layer, leaving a 0.3- mu m-thick cladding layer on the GaInP active layer. Then, n-GaAs selective growth is carried out on the etched cladding layer, and a 4- mu m-wide twin groove just near the ridge stripe structure is fabricated by selectively etching the n-GaAs current blocking layer. Finally, a Si/sub 3/N/sub 4/ insulating block with low refractive index is formed only in the twin groove. As a result of the new structure, the visible laser is realized with not only the index-guide mode but also with low thermal resistivity ( approximately 50 K/W). Transverse-mode stabilized CW operation at room temperature was achieved at a lasing wavelength of 670 mu m, a threshold current of 70 mA, and an external differential quantum efficiency of 20%/facet. >

Single longitudinal mode operation of the electron-beam-pumped semiconductor laser

The influence of the external and internal resonator parameters on the laser emission spectral and spatial characteristics has been investigated. Single longitudinal mode operation of the electron-beam-pumped visible semiconductor laser with an external resonator has been observed. A single-mode peak power of 0.8 W and beam divergence of less than 3° were achieved.

Room-temperature CW operation of AlGaInP double-heterostructure visible lasers

Room-temperature continuous-wave (CW) operation of (Al0.4Ga0.6)0.5In0.5P/Ga0.5In0.5P/(Al0.4Ga0.6)0.5In0.5P double-heterostructure visible semiconductor lasers has been achieved for the first time. CW operation is obtained up to 50° C. The threshold current at 25° C is mA (4.1 kA/cm2). The lasing wavelength is 689.7 nm.

Diode lasers in photomedicine

Recent developments of high-power infrared and visible semiconductor (diode) lasers make this class of miniaturized laser sources very attractive for medical applications. Principles of operation of diode lasers are reviewed, and potential areas of applications are discussed. Possible uses of high-power incoherent diodes in photomedieine are presented.

(Invited) Visible Semiconductor Laser

The state-of-the-art visible semiconductor lasers are reviewed. The characteristics and reliability problems of ternary and quarternary lasers grown on GaAsP compositionally graded layers are presented. The lasing properties and operating life of the transverse mode stabilized AlGaAs visible lasers grown on close lattice matched GaAs substrates are described, particularly on transverse junction stripe (TJS) lasers. TJS lasers oscillate in a single longitudinal mode with the fundamental transverse mode, and have the very low threshold current of 20–30 mA for the wavelengths between 900 and 750 nm. Negligible degradation has been observed in TJS lasers with the lasing wavelength around 780 nm after 4500 hr life test at 50°C with the constant lasing output of 3 mW/facet.