This paper gives a brief historical summary of the development of the field of optical interconnects to silicon integrated circuits. It starts from roots in early optical switching phenomena, proceeds through novel semiconductor and quantum well optical and optoelectronic physics and devices, first proposals for optical interconnects, and optical computing and photonic switching demonstrators, to hybrid integrations of optoelectronic and silicon circuits that may solve basic scaling and other problems for interconnections in future information processing and switching machines.

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Optical interconnects to silicon

A light-emitting device includes a substrate and a light-emitting device section The light-emitting device section includes a light-emitting layer capable of emitting light by electroluminescence, a pair of electrode layers for applying an electric field to the light-emitting layer, an optical section for propagating light generated in the light-emitting layer in a specific direction, and an insulation layer disposed between the pair of electrode layers, having an opening formed in part thereof and can function as a current concentrating layer for specifying a region through which current to be supplied to the light-emitting layer flows via a layer in the opening The optical section has a defect section which forms photonic bandgaps capable of inhibiting a three-dimensional spontaneous emission, and the energy level of the defect section, caused by the defect, is set to be within a specific emission spectrum Light generated in the light-emitting layer is emitted with a three-dimensional spontaneous emission being inhibited by the photonic bandgaps

Light -emitting device

Intermixing the wells and barriers of quantum well structures generally results in an increase in the band gap and is accompanied by changes in the refractive index. A range of techniques, based on impurity diffusion, dielectric capping and laser annealing has been developed to enhance the quantum well intermixing (QWI) rate in selected areas of a wafer; such processes offer the prospect of a powerful and relatively simple fabrication route for integrating optoelectronic devices and for forming photonic integrated circuits (PICS). Recent progress in QWI techniques is reviewed, concentrating on processes which are compatible with PIC applications, in particular the achievement of low optical propagation losses.

https://iopscience.iop.org/article/10.1088/0268-1242/8/6/022/pdf

Quantum well intermixing

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

The fabrication and basic characteristics of a InGaAs/InGaAsP multi-quantum-well (MQW) electroabsorption modulator with a novel structure integrated with a distributed-feedback (DFB) laser are presented. A fundamental study was performed on the applicability of the InGaAs/InGaAsP MQW structure to an electroabsorption-type modulator. Efficient attenuation small hole pileup and small chirp characteristics of a discrete modulator based on this MQW structure were demonstrated experimentally. A study of the controllability of in-plane band-gap energy by the use of selective-area metal-organic chemical vapor deposition (MOCVD) was also demonstrated. The modulator was monolithically integrated with a MQW DFB laser of the same material. Using a low-capacitance semi-insulating buried heterostructure, over 14 GHz modulation under high-light-output operations up to +10 dBm was achieved. Modulation at 10 Gb/s with a modulation voltage swing of only 1 V/sub pp/ demonstrates the potential value of this system for 1.55- mu m lightwave communications. >

InGaAs/InGaAsP MQW electroabsorption modulator integrated with a DFB laser fabricated by band-gap energy control selective area MOCVD

A novel structure electroabsorption modulator/DFB laser integrated device is proposed and demonstrated. Both functional devices consist of MQW structures with different quantum energy levels, which are automatically formed in the same MOCVD run by using a selective area growth technique. A fundamental modulation with a 12.6dB extinction ratio is demonstrated.

Novel structure MQW electroabsorption modulator/DFB-laser integrated device fabricated by selective area MOCVD growth

The local bandgap energy of an InGaAs/InGaAsP multiple quantum well (MQW) structure was precisely adjusted by in-plane Eg control in one-step selective area metalorganic chemical vapor deposition (MOCVD) growth. The technique was then applied to an MQW electroabsorption-modulator integrated distributed feedback (DFB) laser. Experimental results showed superior device characteristics, such as a high extinction ratio of 25 dB and low threshold current of 15 mA. >

High-extinction-ratio MQW electroabsorption-modulator integrated DFB laser fabricated by in-plane bandgap energy control technique

A new structure for a 13 /spl mu/m-wave length beam-expander integrated ridge-waveguide laser is demonstrated that does not require a regrowth step A narrow beam divergence of 54/spl deg/ (lateral) and 189/spl deg/ (vertical) enables a laser diode to be coupled to a cleaved singlemode fibre with an efficiency as high as 33% with a 1 dB alignment tolerance of /spl plusmn/24 /spl mu/m laterally and +15 /spl mu/m vertically >

1.3 µm beam-expander integrated laser grown by single-step MOVPE

Disclosed is a semiconductor optical integrated device and method of fabricating the device, the device having a plurality of quantum well structures, formed on a single substrate, acting as optical waveguides, the plurality of quantum well structures respectively having different lattice mismatches with the substrate and/or different strains (e.g., respectively compressive strain and tensile strain). The method includes selectively depositing the quantum well structures by, e.g., organometallic vapor phase epitaxy on growth regions of the substrate, the growth regions being defined by insulating layer patterning masks, with a width of the growth regions and/or a width of the patterning mask being different for the different quantum well structures. Each quantum well structure includes quantum well layers of III-V or II-VI compound semiconductor material, the Group III or Group II elements each including at least two elements, one having a relatively large atomic diameter and another having a relatively small atomic diameter. Also disclosed is a light receiver that can independently absorb TE-mode and TM-mode light in series, which can be used in a polarized-wave diversity receiver for coherent optical communication.

Semiconductor optical integrated device and light receiver using said device

A new fabrication method of high-quality thickness-tapered semiconductor waveguides is proposed based on controlling in-plane thickness during MOVPE by using a comb-shaped silicon shadow mask. It was used to fabricate a 1.3-/spl mu/m-wavelength narrow-beam (less than 13/spl deg/) InGaAsP-InP laser diode, which achieved high-power (over 20 mW) operation up to 85.

Makoto Takahashi

Papers

Novel structure MQW electroabsorption modulator/DFB-laser integrated device fabricated by selective area MOCVD growth

High-extinction-ratio MQW electroabsorption-modulator integrated DFB laser fabricated by in-plane bandgap energy control technique

1.3 µm beam-expander integrated laser grown by single-step MOVPE

Semiconductor optical integrated device and light receiver using said device

Wide-temperature-range operation of 1.3-μm beam expander-integrated laser diodes grown by in-plane thickness control MOVPE using a silicon shadow mask