Klaus Streubel

Room-temperature continuous-wave operation of 1.54-μm vertical-cavity lasers

We report on the room-temperature continuous-wave operation of vertical-cavity lasers operating at 1.54 /spl mu/m. The devices use a 7 strain-compensated quantum-well active layer sandwiched between two Al(Ga)As-GaAs quarter-wave mirrors joined by wafer fusion. Five device sizes between 8 and 20 /spl mu/m were found to operate continuously at room temperature (23/spl deg/C), The lowest room-temperature continuous-wave threshold current of 2.3 mA was measured on an 8-/spl mu/m diameter device, while the highest continuous-wave operating temperature of 33/spl deg/C was measured on a 12-/spl mu/m device.<<ETX>>

HIGH GAIN-BANDWIDTH-PRODUCT SILICON HETEROINTERFACE PHOTODETECTOR

We report the fabrication of a near-infrared avalanche photodetector with a gain-bandwidth product of over 300 GHz. The detector uses a Si multiplication layer and an InGaAs absorption layer. A 3 dB bandwidth of over 9 GHz was measured for current gains as high as 35. Photocurrent measurements using 1.3 μm light indicate a quantum efficiency for the detector of 0.60, near the limit expected based on the absorber thickness.

Design and analysis of double-fused 1.55-/spl mu/m vertical-cavity lasers

Detailed design and experimental characterization of three generations of double-fused vertical-cavity lasers are described. The result of this design evolution is the first above-room-temperature continuous-wave operation of long-wavelength vertical-cavity lasers. Threshold currents of 2.3 mA and yields greater than 90% have been obtained.

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.

SILICON HETEROINTERFACE PHOTODETECTOR

We report the demonstration of an infrared avalanche photodetector that uses an InGaAs absorption layer and a Si avalanche multiplication layer bonded by wafer fusion. Photocurrent measurements of the silicon heterointerface photodetector showed high response to 1.3 μm light and gains of up to 130. Frequency response measurements for the detectors yielded 3 dB bandwidth products of up to 81 GHz.

Laterally oxidized long wavelength cw vertical‐cavity lasers

Vertical-cavity lasers (VCLs) operating at 1.3 and 1.55 µm wavelengths are potentially low cost sources for optical communications.

Experimental demonstration of a multifunctional long-wavelength vertical-cavity laser amplifier-detector

We report on the first experimental realization of a multifunctional long wavelength /spl lambda/=1.5-/spl mu/m InGaAsP MQW vertical cavity laser amplifier-photodetector. An optical gain of up to 18 dB and a voltage responsivity of 160 V/W is demonstrated.

Temperature sensitivity of 1.54-/spl mu/m vertical-cavity lasers with an InP-based Bragg reflector

We fabricated 1.54-/spl mu/m laser diodes that employ one integrated GaInAsP-InP and one Si-SiO/sub 2/ mirror in combination with a strain-compensated GaInAsP multiquantum-well active layer. Considerable care has to be taken of the temperature performance of the devices. Here, an important parameter is the gain offset between the gain peak wavelength and the cavity resonance. This offset is related to the experimentally accessible photoluminescence (PL) offset between the PL-peak wavelength and the emission wavelength. Vertical-cavity laser (VCL) characteristics such as threshold current and quantum efficiency show an extremely sensitive dependence on this parameter. In this paper, we focus on the temperature performance of our VCLs as a function of the cavity tuning. VCLs designed for PL-offset values between +17 and -16 mm are fabricated and characterized, As expected, the threshold current of all lasers shows a pronounced minimum at low temperatures. The position of this minimum depends on the offset at room temperature (RT) as a parameter. However, it turns out that the minimum threshold current is not obtained by matching gain peak and cavity wavelength for that temperature. The observed behavior is described well by calculations, taking into account the temperature dependence of the optical gain, of the cavity resonance, and of the cavity losses. The model is a valuable tool to tune the lasers for example low threshold current or reduced temperature sensitivity.

Monolithic InP-biased tunable filter with 10-nm bandwidth for optical data interconnects in the 1550-nm band

We report the design and fabrication of micromechanically tunable filters with a 10-nm bandwidth for the 1550-nm wavelength range. The electrostatic actuation provides a tuning range of 30 nm and a low actuation power. The filters consist of a monolithic, vertical Fabry-Perot resonant cavity based on an epitaxial InGaAsP-InP Bragg reflector. An actuable InP micromechanical structure suspended over a 1/spl times/-thick air-gap provides for the tuning of the cavity. Our design aims primarily for a device that is simple, robust and that can be integrated with an InP-based photodetector or emitter in a low-cost component for optical data interconnects.

Photonic crystal structure effect on the enhancement in the external quantum efficiency of a red LED

The enhancement in external quantum efficiency of a red light-emitting diode (LED) from photonic crystal (PhC) hole patterns was investigated. A red LED was chosen because its epitaxial layers are relatively free from defects as compared to GaN-based LEDs. The peak emission wavelength was 642 nm, and a triangular-lattice PhC was designed with a hole diameter to lattice distance ratio of 0.5. The lattice distance to wavelength ratio (a/lambda) was varied from 0.2 to 4.6 in order to evaluate the enhancement in the external quantum efficiency. An improvement in efficiency greater than 75% was obtained for a/lambda between 0.6 and 2.0. This improvement of the optical characteristics occurred with unchanged electrical properties