A review is presented of the properties of interdigitated metal-semiconductor-metal (MSM) Schottky barrier photodetectors based on the InGaAs-InP material system, and the performance achieved by experimental devices is discussed. The experimental work concentrates on the barrier-enhanced lattice-matched InAlAs-InGaAs device grown by low pressure organometallic chemical vapor deposition (OMCVD), which has to date yielded detectors with the highest performance characteristics. Current research on their integration with FETs to form monolithic receivers and with waveguides for on-chip optical signal processing is also included. >

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InGaAs metal-semiconductor-metal photodetectors for long wavelength optical communications

Semiconductor photonic integrated circuits (PICs) refer to that subset of optoelectronic integrated circuits (OEICs) which focus primarily on the monolithic integration of optically interconnected guided-wave optoelectronic devices. The principal motivation for PIC research is the expected cost reduction and packaging robustness associated with replacing individually aligned, single-mode optical connections between discrete optoelectronic devices with lithographically produced integrated waveguides. This field has recently seen significant advances resulting from improved III-V epitaxial crystal growth and related processing techniques. A discussion is presented of the design and fabrication issues, illustrated by a number of recently demonstrated InP-based PICs. >

Semiconductor photonic integrated circuits

The past few years a lot of effort has been put in the development and fabrication of III-V semiconductor waveguiding devices with monolithic integrated mode size converters (tapers). By integrating a taper with a waveguide device, the coupling losses and the packaging cost of OEICs in future fiber-optical networks can be much reduced. This paper gives an overview of different taper designs, the possible fabrication technologies and performances of tapered devices.

A review on fabrication technologies for the monolithic integration of tapers with III-V semiconductor devices

Improved performance of 1.5- mu m wavelength lasers and laser amplifiers using strained In/sub x/Ga/sub 1-x/As-InGaAsP quantum well devices is reported. The device structures fabricated to study the effects of strained quantum wells on their performance are described. These devices showed TM mode gain, demonstrating the strain-induced heavy-hole-light hole reversal in the valence band. Lasers using these tensile strained quantum wells show higher and narrower gain spectra and laser amplifiers have a higher differential gain compared to compressively strained quantum well devices. Consequently, the tensile strained quantum well lasers show the smallest linewidth enhancement factor alpha =1.5 (compression alpha =2.5) and the lowest K-factor of 0.22 ns (compression K=0.58 ns), resulting in an estimated intrinsic 3 dB modulation bandwidth of 40 GHz (compression 15 GHz). >

High-performance 1.5 mu m wavelength InGaAs-InGaAsP strained quantum well lasers and amplifiers

The current status of semiconductor lasers used in coherent optical fiber communications is reviewed for nonexperts in the field. The issues of spectral purity, tuning, modulation, and advanced fabrication methods for photonic integration are discussed, with examples drawn from current experimental devices. >

Semiconductor lasers for coherent optical fiber communications

The use of ultrathin etch-stop techniques to expand the vertical optical mode size adiabatically in 1.5- mu m InGaAs/InGaAsP MQW lasers using a tapered-core passive intracavity waveguide structure is discussed. 30% differential quantum efficiency out the tapered facet, far-field FWHM of approximately 12 degrees and a butt-coupling efficiency into a cleaved fiber of -4.2 dB, with -1-dB alignment tolerances of approximately +or-3 mu m, were achieved. >

Tapered waveguide InGaAs/InGaAsP multiple-quantum-well lasers

We describe the fabrication and performance of the first integrated heterodyne receiver capable of actual heterodyne data reception. Integrating a continuously tunable 1.5 μm MQW-DBR laser with a single-mode directional coupler/switch and zero-bias MQW waveguide photodetectors, we have achieved error-free reception of FSK-modulated pseudorandom digital code at 105 Mbit/s.

GaInAs/GaInAsP multiple-quantum-well integrated heterodyne receiver

Low threshold and high efficiency operation of strained layer multiple quantum well InGaAs/InGaAsP lasers at 1.5 micrometres wavelength is demonstrated. Current thresholds as low as 2.2 mA with threshold current densities of 440 A/cm2 have been obtained. With 7.3 mA threshold current, quantum efficiency was 65%/front facet. At 20 mW CW output power the drive current was as low as 53 mA.

Low threshold highly efficient strained quantum well lasers at 1.5 micrometre wavelength

A distributed Bragg reflector strained-layer multiple-quantum-well laser at 1.5- mu m wavelength with an integrated tapered waveguide beam expander is discussed. The far-field FWHMs in the lateral and vertical directions are 10 and 15 degrees , respectively. A quantum efficiency of 17% out the tapered facet was measured with a corresponding threshold current of 28 mA. The alignment tolerances for coupling into a cleaved single-mode fiber are 9.5 and 7.5 mu m FWHM in the lateral and vertical directions, respectively. A 3-dB improvement for single-mode fiber coupling using a SELFOC lens was obtained. >

Short-cavity distributed Bragg reflector laser with an integrated tapered output waveguide

A technique is presented for fabricating intersecting waveguides with a sharp junction vertex. This technique was demonstrated by fabricating buried rib waveguide Y branches on InP with a junction vertex width of about 1/8 mu m. These Y branches had lower loss than the regular blunt Y branches but suffered from a dissimilar splitting coefficient between the two arms. This technique may also be useful for fabricating other waveguide elements such as crossed waveguides, zero gap directional couplers, and optical switches. A comparison with theoretical calculations is also given. >

M. Oron

Papers

Tapered waveguide InGaAs/InGaAsP multiple-quantum-well lasers

GaInAs/GaInAsP multiple-quantum-well integrated heterodyne receiver

Low threshold highly efficient strained quantum well lasers at 1.5 micrometre wavelength

Short-cavity distributed Bragg reflector laser with an integrated tapered output waveguide

Buried rib passive waveguide Y junctions with sharp vertex on InP