The decade of the 1990's is an opportune time for scientists and engineers to create cost-effective silicon "superchips" that merge silicon photonics with advanced silicon electronics on a silicon substrate. We can expect significant electrooptical devices from Column IV materials (Si, Ge, C and Sn) for a host of applications. The best devices will use strained-layer epitaxy, doped heterostructures, and bandgap engineering of quantum-confined structures. This paper reviews Si-based photonic components and optoelectronic integration techniques, both hybrid and monolithic. >

Silicon-based optoelectronics

Chromophores with optimized second-order optical nonlinearity to optical loss ratios are synthesized, poled with an electrical field, and coupled into hardened polymer matrixes. Acentric order, which is necessary for electro-optic activity, is optimized by the consideration of chromophore−chromophore electrostatic interactions as well as chromophore−poling field interactions and thermal collisions which randomize chromophore orientations with respect to the applied field direction. Reactive ion etching and/or multicolor photolithography are used to fabricate buried channel waveguide structures out of the resulting polymeric electro-optic materials and to integrate polymeric waveguides with silica optical fibers. Tapered transitions are developed to minimize coupling (insertion) loss. Both vertical and horizontal integration of polymeric electro-optic modulator circuitry with semiconductor very large scale integration circuitry is demonstrated. Modulation to 113 GHz is demonstrated. Polymeric modulators ar...

http://depts.washington.edu/eooptic/publications/files/IndEngChemRescgi.pdf

Polymeric Electro-optic Modulators: From Chromophore Design to Integration with Semiconductor Very Large Scale Integration Electronics and Silica Fiber Optics

Wafer-level heterogeneous integration technologies for microoptoelectromechanical systems (MOEMS), microelectromechanical systems (MEMS), and nanoelectromechanical systems (NEMS) enable the combination of dissimilar classes of materials and components into single systems. Thus, high-performance materials and subsystems can be combined in ways that would otherwise not be possible, and thereby forming complex and highly integrated micro- or nanosystems. Examples include the integration of high-performance optical, electrical or mechanical materials such as monocrystalline silicon, graphene or III-V materials with integrated electronic circuits. In this paper the state-of-the-art of wafer-level heterogeneous integration technologies suitable for MOEMS, MEMS, and NEMS devices are reviewed. Various heterogeneous MOEMS, MEMS, and NEMS devices that have been described in literature are presented.

Wafer-Level Heterogeneous Integration for MOEMS, MEMS, and NEMS

An optical assembly, such as a multiple output diode laser pump source for EDFAs, is formed by pressing an optical array emitter chip against a standoff structure protruding from a submount such that the emitter chip deforms to match the curvature of the standoff structure. An IO chip is also juxtaposed against the standoff structure such that its optical receivers can receive optical energy from the emitter chip. The IO chip can provide various optical functions, and then provide an optical array output for coupling into an optical fiber array. The standoff structure preferably contacts the emitter chip over an aggregate contact area much smaller than the area by which the emitter chip overlaps the submount. The materials used for bonding the emitter chip and the IO chip to the submount are disposed in the recesses between standoffs and not on the contact surfaces of the standoff structure.

Multi-channel laser pump source for optical amplifiers

The ability to tailor compound semiconductors and to integrate them onto foreign substrates can lead to superior or novel functionalities with a potential impact on various areas in electronics, optoelectronics, spintronics, biosensing, and photovoltaics. This review provides a brief description of different approaches to achieve this heterogeneous integration, with an emphasis on the ion-cut process, also known commercially as the Smart-Cut TM process. This process combines semiconductor wafer bonding and undercutting using defect engineering by light ion implantation. Bulk-quality heterostructures frequently unattainable by direct epitaxial growth can be produced, provided that a list of technical criteria is fulfilled, thus offering an additional degree of freedom in the design and fabrication of heterogeneous and flexible devices. Ion cutting is a generic process that can be employed to split and transfer fine monocrystalline layers from various crystals. Materials and engineering issues as well as our current understanding of the underlying physics involved in its application to cleaving thin layers from freestanding GaN, InP, and GaAs wafers are presented.

/pdf/heterogeneous-integration-of-compound-semiconductors-3i0i8phv1e.pdf

Heterogeneous Integration of Compound Semiconductors

Passive alignment of semiconductor lasers and singlemode fibres has been achieved for the first time using a micromachined silicon subtrate. Mechanical alignment features fabricated on the substrate surface were used to align the active regions of an InGaAsP/InP laser array to four single-mode fibres held in V grooves. Optical coupling efficiencies have been achieved that are comparable to values obtained using the conventional technique of active fibre manipulation. The approach, called silicon waferboard, offers the potential for low-cost optoelectronic device packaging as well as a means for dense hybrid integration of optoelectronic, electronic and optical components required for multifibre, multichip systems.

Passive coupling of InGaAsP/InP laser array and singlemode fibres using silicon waferboard

Individually addressable, four-channel transmitter arrays operating at data rates of 1 Gb/s have been developed based on a hybrid optoelectronic integration approach called silicon waferboard. A key feature of silicon waferboard is the use of mechanical alignment features fabricated on the surface of a silicon chip that enable passive optical alignment of components such as lasers and optical fibers. The transmitter array, which operates at a wavelength of 1.3 mu m, comprises a four-channel InGaAsP/InP laser array that is passively aligned to four single-mode fibers held in V-grooves. The transmitter array also includes a four-channel GaAs MESFET driver array chip that provides high-speed drive currents to the individual lasers. The laser array, driver array, and optical fibers are all spaced on 350- mu m centers, which results in a four-channel transmitter array that fits within a width of only 2 mm. Transmitter array waferboards were housed in a specially developed package to permit high-frequency characterization. These transmitter array modules have demonstrated operation at data rates of 1 Gb/s per channel, with an interchannel crosstalk of -29 dB. >

Gigabit transmitter array modules on silicon waferboard

A heterostructure device includes a ridge-waveguide laser (11) monolithically integrated with a ridge-waveguide rear facet monitor [RFM] (12). An integral V-groove etched directly into the device substrate (10) enables passive alignment of an optical fiber (13) to the active region (11-1) of the laser (11). The laser and RFM facets were formed using an in-situ multistep reactive ion etch process.

A monolithically integrated semiconductor structure and method of fabricating such structure

A new thin-film transfer technique has been developed that eliminates the handling of fragile, free-standing films. This, process was used to demonstrate the first long wavelength laser fabricated on a host substrate by a thin-film transfer technique. Ridge waveguide lasers operating at a wavelength of 1.3 mu m were fabricated on both GaAs and silicon substrates. The light-current characteristics of these transferred lasers were comparable to conventional lasers.<
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1.3 mu m InGaAsP ridge waveguide laser on GaAs and silicon substrates by thin film transfer

An InGaAsP/InP laser monolithically integrated with a rear facet monitor and a fiber V-groove has been demonstrated for the first time. The integrated device incorporates an etched-facet laser fabricated using an in situ, multistep, reactive ion etch process. The integrated V-groove, which is etched directly into the InP substrate, is designed to enable passive alignment of an optical fiber to the active region of the laser. Passive coupling efficiencies of 18% and 8% have been obtained using cleaved multimode and single mode fibers, respectively. Responsivities of the rear facet monitor were as high as 0.49 A/W. >

A.J. Negri

Papers

Passive coupling of InGaAsP/InP laser array and singlemode fibres using silicon waferboard

Gigabit transmitter array modules on silicon waferboard

A monolithically integrated semiconductor structure and method of fabricating such structure

1.3 mu m InGaAsP ridge waveguide laser on GaAs and silicon substrates by thin film transfer

Monolithically integrated laser/rear-facet monitor arrays with V-groove for passive optical fiber alignment