Kaori Naganuma

High-Power (over 100 mW) Green Laser Diodes on Semipolar

Continuous-wave operation of InGaN green laser diodes (LDs) on semipolar {2021} GaN substrates with output powers of over 100 mW in the spectral region beyond 530 nm is demonstrated. Wall plug efficiencies (WPEs) as high as 7.0–8.9% are realized in the wavelength range of 525–532 nm, which exceed those reported for c-plane LDs. The longest lasing wavelength has reached 536.6 nm under cw operation. These results suggest that the InGaN green LDs on the {2021} plane are better suited as light sources for applications requiring wavelengths over 525 nm.

\{20\bar{2}1\}

True green GaInN laser diodes with a lasing wavelength above 525 nm under continuous wave operation have been successfully fabricated on semipolar {2021} GaN substrates by improving both the diode structure and epitaxial growth conditions. At a case temperature of 55 °C, their lifetime was estimated to be over 5000 h for an optical output power of 50 mW and over 2000 h at 70 mW.

GaN Substrates Operating at Wavelengths beyond 530 nm

AlInP/GaInP 7 W laser arrays with a uniform intensity distribution and a low smile of 1 /spl mu/m have been developed for a display system. The estimated lifetime exceeds 10000 hours under CW operation.

Long-Lifetime True Green Laser Diodes with Output Power over 50 mW above 525 nm Grown on Semipolar \{20\bar{2}1\} GaN Substrates

We have applied zinc diffused window structures to 640 nm broad area stripe laser diodes (BALDs) for the first time. A solid-phase zinc diffusion technique was used for a thick single quantum well (SQW) in GaInP employing the short wavelength and disordered active layer possessed a blue shift of 58 nm in photoluminescence spectrum. We fabricated 10 mm arrays including twenty-five BALDs and each BALD consists of a 60 μm ridge stripe and a 1000 μm cavity. An initial catastrophic optical damage (COD) level of the window laser was increased by four times of a conventional none-window laser. A long-term reliability under automatic current control was investigated for initial output powers of 13W and 15W which overcome a previous demonstration of 7.2 W. Measured degradations within a period of 1000-hours were 5 % or less, in contrast a half-life period of our conventional none-window laser with an initial output power of 10 W was only 120-hours. Therefore the window structure improved the BALD in terms of the COD level and the long-term reliability.

Highly reliable 7 W operation of 644 nm wavelength laser diode arrays with top-hat near field pattern

A 0.3 W operation for a single emitter broad area red laser at 45degC was achieved, for the first time, and a highly reliable 25 emitter array operation of 6.6 W at 25degC. The laser array is composed of 25 broad stripe lasers with a stripe pitch of 400 mum. The operation current, operation voltage, slope efficiency, emission wavelength and the energy conversion efficiency of the laser diode were obtained. Lifetime test was performed under constant current mode.