Dan Vacar

Manufacturable Photonic Crystal Single-Mode and Fluidic Vertical-Cavity Surface-Emitting Lasers

We describe a robust manufacturing process for single-mode photonic crystal (PhC) vertical-cavity surface-emitting lasers (VCSELs). Various PhC designs are investigated to determine endlessly single-mode designs, whereby the same PhC design yields single-mode operation for three different wavelengths (780, 850, and 980 nm). The fabrication of the PhC pattern is based on a self-aligned optical lithography process. The fabrication process results in VCSELs with a maximum output power greater than 1 mW under continuous-wave (CW) operation with side-mode suppression ratio greater than 35 dB. We also show microfluidic laser structures that are enabled by our fabrication process, which integrate fluid channels into VCSELs. Optical and electrical properties of these microfluidic VCSELs are investigated with and without fluids present under CW and pulsed operation. A shift of the lasing wavelength is found with fluid insertion.

Scaling vertical-cavity surface-emitting laser reliability for petascale systems

We evaluate vertical-cavity surface-emitting lasers (VCSELs) reliability for next-generation high-productivity computers wherein several hundreds of terabits of bandwidth are envisioned. VCSEL failure rates are modeled, and an empirical relationship for VCSEL scaling versus bit rate and aperture is presented to explore the reliability of VCSEL-based links. The effects of VSCEL sparing, water cooling, and redundancy at the system level are analyzed.

VCSEL reliability: a user's perspective

VCSEL arrays are being considered for use in interconnect applications that require high speed, high bandwidth, high density, and high reliability. In order to better understand the reliability of VCSEL arrays, we initiated an internal project at SUN Microsystems, Inc. In this paper, we present preliminary results of an ongoing accelerated temperature-humidity-bias stress test on VCSEL arrays from several manufacturers. This test revealed no significant differences between the reliability of AlGaAs, oxide confined VCSEL arrays constructed with a trench oxide and mesa for isolation. This test did find that the reliability of arrays needs to be measured on arrays and not be estimated with the data from singulated VCSELs as is a common practice.

Reverse-bias emission sheds light on the failure mechanism of degraded vertical-cavity surface-emitting lasers

The phenomenon of reverse-bias electroluminescence (EL) has been exploited extensively to elucidate the physics of failure of Si-based semiconductor devices. In this article, we study the reverse-bias emission of vertical-cavity surface-emitting lasers (VCSELs) that have been stressed under accelerated temperature, humidity, and bias. Using quantitative emission microscopy in conjunction with other electrical and optical measurements, we show that the dark line defect dislocation network responsible for VCSEL degradation can be imaged directly as reverse-bias EL and that the spectra of the reverse-bias EL provide further insight into the failure mechanism.