Room-temperature operation of GaN-based blue-violet laser diodes fabricated on sapphire substrates using high-temperature-grown single-crystal AlN buffer layers

2003 ◽  
Vol 200 (1) ◽  
pp. 126-130 ◽  
Author(s):  
Yasuo Ohba ◽  
Susumu Iida
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Room Temperature ◽  
Laser Diodes ◽  
Buffer Layers ◽  
Sapphire Substrates ◽  
Aln Buffer ◽  
Grown Single Crystal ◽  
Room Temperature Operation

Room Temperature Operation of Visible (λ =658.6 nm) InGaAsP DH Laser Diodes on GaAsP

1985 ◽  
Vol 24 (Part 2, No. 7) ◽  
pp. L551-L552 ◽  
Author(s):  
Sadao Fujii ◽  
Shiro Sakai ◽  
Masayoshi Umeno
Keyword(s):  
Room Temperature ◽  
Laser Diodes ◽  
Room Temperature Operation

scholarly journals Room Temperature CW Operation of GaN-based Blue Laser Diodes by GaInN/GaN optical guiding layers

2000 ◽  
Vol 5 (S1) ◽  
pp. 1-7 ◽  
Author(s):  
Masayoshi Koike ◽  
Shiro Yamasaki ◽  
Yuta Tezen ◽  
Seiji Nagai ◽  
Sho Iwayama ◽  
...  
Keyword(s):  
Room Temperature ◽  
Continuous Wave ◽  
Laser Diodes ◽  
Threshold Current ◽  
Crystal Defects ◽  
Blue Laser ◽  
Buffer Layers ◽  
Continuous Wave Laser ◽  
Cw Operation ◽  
First Time

GaN-based short wavelength laser diodes are the most promising key device for a digital versatile disk. We have been improving the important points of the laser diodes in terms of optical guiding layers, mirror facets. The continuous wave laser irradiation at room temperature could be achieved successfully by reducing the threshold current to 60 mA (4 kA/cm2). We have tried to apply the multi low temperature buffer layers to the laser diodes for the first time to reduce the crystal defects.

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2001 ◽  
Author(s):  
Nagaraj K. Arakere
Keyword(s):  
High Pressure ◽  
Shear Stress ◽  
High Temperature ◽  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Turbine Blades ◽  
The Core ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4 and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the Space Shuttle Main Engine (SSME) fuel turbopump are discussed. During testing many turbine blades experienced Stage II non-crystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β = 45+/- 15 degrees tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined Low Cycle Fatigue (LCF) properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75 F – 1800 F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for LCF data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the LCF data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature LCF data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with LCF test data. These curve fits can be used for assessing blade fatigue life.

Room-Temperature Pulsed Operation of GaInNAs Laser Diodes with Excellent High-Temperature Performance

1996 ◽  
Vol 35 (Part 1, No. 11) ◽  
pp. 5711-5713 ◽  
Author(s):  
Masahiko Kondow ◽  
Shin'ichi Nakatsuka ◽  
Takeshi Kitatani ◽  
Yoshiaki Yazawa ◽  
Makoto Okai
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Laser Diodes ◽  
Temperature Performance
Sign in / Sign up

Export Citation Format

Share Document