Yiu-Man Wong

Technology development of a high-density 32-channel 16-Gb/s optical data link for optical interconnection applications for the optoelectronic technology consortium (OETC)

A parallel, 32-channel, high density (140 /spl mu/m pitch), 500 Mb/s NRZ, point-to-point, optical data link has been fabricated using existing GaAs IC, silicon optical bench (SiOB), and multichip module (MCM-D) technologies. The main components of the transmitter and the receiver modules are a GaAs-based vertical cavity surface emitting laser (VCSEL) array at 850 mn with its IC driver array chip and an integrated metal-semiconductor-metal (MSM) receiver (photodetector and signal processing circuits) array at 850 nm. The package module uses a modified 164 I/O JEDEC premolded plastic quad flat pack (PQFP) in combination with a polymer film integrated circuit (POLYFIC) chip carrier. The electrical input and output are 500 Mb/s NRZ binary signals. The optical I/O in both modules consists of a directly-connectorized (nonpigtail) fiber array block that plugs into the 32/spl times/1 optical fiber ribbon directly on one side and accepts 32 optical signals from the SEL array or delivers them to the MSM receiver array via a gold-coated 45/spl deg/ polished fiber array mirror. The MACII-32 ribbon cable is an enhanced version of the standard MACII connector ribbon cable. This paper characterizes key components of the optical data link, describes its package design, and discusses preliminary component and optical data link test results. >

Study of Ni as a barrier metal in AuSn soldering application for laser chip/submount assembly

The possibility of replacing Pt in the Ti/Pt/Au base and traditionally used metallurgical structure by Ni, while bonding InP laser chip to a submount with AuSn (80% Au) solder, has been investigated. Various Ni‐based metal alloys have been prepared by evaporation. Reflow experiments were conducted in a chamber under forming gas‐controlled ambient. The Ti/Ni/AuSn system provided much longer surface local freezing duration compared to the Ti/Pt/AuSn system. Scanning electron microscopy analysis revealed a smoother surface morphology for the Ti/Ni/AuSn system after the metal refroze. Auger electron spectroscopy depth profiles indicated the formation of a Ni‐Sn‐Au interacted layer. The interaction took place in two steps: the first stage was the dissolution of Ni into the Au‐Sn liquid followed by precipitation of a Ni‐Sn‐Au intermetallic compound; the second stage was a solid‐state interdiffusion of Sn, Au, and Ni which occured in the interacted layer and in the original Ni layer. The latter step was a diffus...

Bonding of InP laser diodes by Au-Sn solder and tungsten-based barrier metallization schemes

Ti/W/Au-Sn and Ti/WxMy/Au-Sn schemes were studied as alternative metallization schemes to the traditionally used Ti/Pt/Au-Sn system for the bonding of InP laser diodes to heatsinks, and in particular to CVD diamond parts. The study comprised the Ti/W, Ti/W1(Au-Sn) and Ti/W1(Ni-Sn) barrier metal schemes, co-deposited in between the Au-Sn solder and the submount. In particular, reactivity and thermodynamic stability of the systems, acid the integrity of the barrier metal to the AuSn solder interface through the thermal bonding refreezing and reflow cycles were tracked. Premature freezing of the solder through the bonding cycles was attributed to the intermixing of the underlying barrier metal and the solder, suggesting an insufficient thermodynamic stability. Dewetting of the solder from the barrier metals through the reflowing cycle, subsequent to the completion of the bonding cycle, occurs due to the excellent inert nature of the solder to the barrier system, but exhibited the deficiency of poor solder to barrier metal adhesion. The TIM, system performed as an absolute inert barrier under the Au-Sn solder, in which no premature freezing phenomena were observed through the bonding cycle, resulting, however, in a delamination of the solder from the Ti/W, while reflown both under flux and forming-gas. In order to maintain the stable nature of this system, but to improve the barrier-solder interfacial integrity, W-Au, W-AuSn and W-NiSn co-deposited intermediate adhesion layers were introduced in between the W layer and the Au-Sn solder. As a result, the adhesion of the solder to the barrier metal improved, while the most stable performance was observed while applying the W/W(NiSn) barrier system under the Au-Sn solder. The first local freezing phenomenon of the bonding solder, while using this system, was observed only after heating the sample to 320 degrees C for more than 3 min and more than 1 h was needed to completely freeze the entire solder. in addition, an excellent solder to metal interfacial integrity was observed through the gas and flux reflow cycle. Thus, the W/W(NiSn) barrier metallization is recommended as a superior scheme to replace the traditionally used Ti/Pi system for bonding laser diodes to any type of submount using Au-Sn solder.

Hybrid integration of surface-emitting microlaser chip and planar optics substrate for interconnection applications

The bonding of a monolithic array of surface-emitting microlasers onto a glass substrate that contains a matching array of microlenses and mirrors is reported. The bonding was achieved by flip-chip solder bump bonding using indium as the solder material. The alignment precision is within +or-2 mu m. The optical substrate provides a simple interconnection scheme that routes the light from each laser to well defined output positions. >

OptoElectronic Technology Consortium (OETC) parallel optical data link: components, system applications, and simulation tools

This paper discusses the present state of the art of components, systems, and application technology related to parallel optical data links (ODL) as demonstrated by the OptoElectronic Technology Consortium (OETC). Parallel ODL technology is poised for large volume commercialization despite some uncertainties in industrial standards and system applications. This is fueled by the demand for high-bandwidth to support the upcoming information age. To meet the need for low-cost, broadband digital multimedia services, parallel ODL technology faces the challenge of providing reasonable cost/performance ratios when compared with other established technologies. Responding to this challenge has required the integration of a number of state-of-the-art component technologies (e.g. VCSEL, monolithic integrated photoreceiver, MCM, GaAs IC, optical array connector and cable) with system designs and applications.

Optical performance of low-cost self-aligned MCM-D based optical data links

We discuss the details of the design and performance of the optics proposed for a MCM-D based low-cost multimode optical data link. The optical system is completely self-aligned, taking advantage of flip-chip bonding, solder-bump self-alignment, mechanical self-alignment using silicon micromachining, and precision plastic components. Preliminary results demonstrate that the integral-lens design of the opto electronic device significantly effects the coupling efficiency and the requisite tolerances of the components that comprise the coupling optics. We show that coupling efficiencies of 70% or better are readily achievable with piece parts made using standard practices. These coupling efficiencies compare favorably with those in actively-aligned optical subassemblies used in current optical data link products.

A memory function equation approach to the kinetics of spinodal decomposition in the very early linear regime

The equations of Metiu, Kitahara and Ross for the kinetics of the spinodal decomposition are generalized in both time and space by using the idea of a memory function. Reinterpretation is given as to how correlations between the change in densities, at different time and spatial points will affect the kinetics of the phase separation. This new interpretation leads to an additional curvature in the spectrum of the observed rate of spinodal decomposition. Our generalized theory is in qualitative agreement with (i) the Boltzman equation approach of Nonnenmacher if a simple memory function is inserted and (ii) the result of Kawasaki and coworkers, namely that a time-dependent rate is found when a persistent range of time correlation is introduced. If persistent spatial correlation is introduced, we predict a divergent behavior of the rate constant at small k. This divergent behavior is also seen in the linearized hydrodynamics approach of Haus and Kitahara.

Comments on the effect of disorder on transport with intermediate degree of coherence: Calculation of the mean square displacement

We use the generalized master equation with a simple exponential memory but with disorder in its spatial dependence to analyze the combined effect of coherence and randomness on the transport of quasiparticles. We calculate the mean-square-displacement and find that it retains well-known properties in the presence of randomness.

Spatial profile of the steady-state exciton distribution in doped molecular crystals☆

Abstract We present calculations of the steady-state spatial distribution of excitons created continuously by illumination and depleted continuously by radiative decay in a doped molecular crystal, e.g. tetracene-doped anthracene. The calculation is exact for low guest concentrations and allows explicit description of the hole in the exciton distribution that surrounds a trapping site.

Optoelectronic packaging technology development of a high density 32-channel 16 Gbps optical data link for the optoelectronic technology consortium (OETC)

Summary form only given. A parallel, 32 channel, high density (140 /spl mu/m pitch) 500 Mbps/channel NRZ optical data link has been successfully fabricated using existing GaAs IC, silicon optical bench, and multichip module technologies. Packaging designs, its implementation, and link characterization will be discussed.