J.J. Dudley

LOW THRESHOLD, WAFER FUSED LONG WAVELENGTH VERTICAL CAVITY LASERS

We demonstrate electrically injected InGaAsP (1.3 μm) vertical cavity lasers (VCLs) fabricated on GaAs substrates and employing GaAs/AlAs mirrors. The technique of wafer fusion allows for integration of GaAs/AlAs mirrors with InP double heterostructures without degradation of device performance, despite a 3.7% lattice mismatch between the wafers. The wafer fused VCLs have the lowest threshold current (9 mA) and lowest threshold current density (9.5 kA/cm2) and the highest characteristic temperature (T0=67 K) reported to date of any room‐temperature long wavelength VCL.

Double‐fused 1.52‐μm vertical‐cavity lasers

We demonstrate a novel long‐wavelength vertical‐cavity laser structure employing two AlAs/GaAs mirrors and a strain‐compensated InGaAsP quantum‐well active region. The lasers have been fabricated by wafer fusion and have the lowest room‐temperature pulsed threshold current density of 3 kA/ cm2 at 1.52 μm. Eight laser sizes ranging from 9 to 60 μm were fabricated with threshold currents as low as 12 mA. Single transverse mode operation was observed on the 9 μm device, while other devices lased multimode. The maximum pulsed output power was 7 mW.

GAAS TO INP WAFER FUSION

This paper presents an analysis of the various properties of the fused interface between GaAs and InP. Interface dislocations are characterized by transmission electron microscopy. Bipolar electrical properties are studied by electron beam induced current measurements and by electrical measurements of fused diode and laser structures. Absorptive optical losses at the interface are estimated from measurements on fused Fabry–Perot resonators and optical scattering losses from interface roughness are estimated by atomic force microscopy. Finally a preliminary mechanical analysis of fracture patterns of fused mesas is presented. The results from our analysis are used to develop guidelines for the fabrication of fused optoelectronic devices.

144 °C operation of 1.3 μm InGaAsP vertical cavity lasers on GaAs substrates

We report lasing at temperatures as high as 144 °C in long‐wavelength InGaAsP vertical cavity lasers. The devices are optically pumped and employ a novel cavity design using GaAs/AlAs quarter‐wavelength stacks for one mirror. The characteristic temperature T0 of the device increases from 42 K at room temperature to 81 K at temperatures above 80 °C as the gain peak moves into resonance with the longer wavelength cavity mode.

Low-threshold, high-temperature pulsed operation of InGaAsP/InP vertical cavity surface emitting lasers

Room-temperature pulsed operation of InGaAsP (1.3 mu m)/InP vertical cavity surface emitting lasers has been achieved with threshold current as low as 50 mA using a constricted-mesa structure with dielectric mirrors. Above-room-temperature operation has also been realized with a maximum operation temperature of 66 degrees C. Pulsed and continuous-wave threshold currents at 77 K are 1.5 and 3.9 mA, respectively.<<ETX>>

High quantum efficiency and narrow absorption bandwidth of the wafer-fused resonant In/sub 0.53/Ga/sub 0.47/As photodetectors

We demonstrate greater than 90% quantum efficiency in an In/sub 0.53/Ga/sub 0.47/As photodetector with a thin (900 /spl Aring/) absorbing layer. This was achieved by inserting the In/sub 0.53/Ga/sub 0.47/As/InP epitaxial layer into a microcavity composed of a GaAs/AlAs quarter-wavelength stack (QWS) and a Si/SiO/sub 2/ dielectric mirror. The 900-/spl Aring/-thick In/sub 0.53/Ga/sub 0.47/As layer was wafer fused to a GaAs/AlAs mirror, having nearly 100% power reflectivity. A Si/SiO/sub 2/ dielectric mirror was subsequently deposited onto the wafer-fused photodiode to form an asymmetric Fabry-Perot cavity. The external quantum efficiency and absorption bandwidth for the wafer-fused RCE photodiodes were measured to be 94/spl plusmn/3% and 14 nm, respectively. To our knowledge, these wafer-fused RCE photodetectors have the highest external quantum efficiency and narrowest absorption bandwidth ever reported on the long-wavelength resonant-cavity-enhanced photodetectors.<<ETX>>

Analysis of wafer fusing for 1.3 μm vertical cavity surface emitting lasers

We report low densities of electrically active defects and low optical losses at the wafer fused interface between InP and GaAs. Electron beam induced current analysis shows electrically active defects with an average spacing of 4.5 μm at the interface and significantly lower densities 0.4 μm from the fused interface. Optical measurements of a Fabry–Perot resonator made by fusing an InP epilayer to a GaAs/AlAs mirror demonstrate a 3% increase in mirror transmission after fusing and negligible absorption at the fused interface. Based on these results, we present design considerations for fused surface emitting lasers.

Temperature dependence of the properties of DBR mirrors used in surface normal optoelectronic devices

The variation in the center wavelength of distributed Bragg reflectors used in optoelectronic devices, such as surface emitting lasers and Fabry-Perot modulators, is measured as the temperature of the mirrors changes over the range 25 degrees C to 105 degrees C. An analytic expression for the shift in center wavelength with temperature is presented. The mirrors measured are made of InP/InGaAsP ( lambda /sub gap/=1.15 mu m), GaAs/AlAs, and Si/SiN/sub x/. The linear shifts in center wavelength are 0.110+or-0.003 nm/ degrees C, 0.087+or-0.003 nm/ degrees C, and 0.067+or-0.007 nm/ degrees C for the InP/InGaAsP, GaAs/AlAs, and Si/SiN mirrors, respectively. Based on these data, the change in penetration depth with temperature is calculated.<<ETX>>

Wafer fused long wavelength vertical cavity lasers

We demonstrate lasing in InGaAsP (1.3 /spl mu/m) vertical cavity lasers employing GaAs/AlAs mirrors on a GaAs substrate. The lasers operate pulsed at 300 K with a threshold current of 9 mA and they operate continuous wave at temperatures as high as 230 K.<<ETX>>

Manufacturing of oxide VCSEL at Hewlett Packard

We have developed a commercially manufacturable oxide VCSEL process. Good uniformity control in epitaxial thickness and oxide aperture is found to be important in achieving high yield. The manufactured VCSELs have superior performance with operating voltage less than 2 V. Preliminary results show that oxide VCSEL reliability is similar to that of proton-implanted VCSELs.