Novel 1.3-micron high-speed directly modulated semiconductor laser device designs and the development of wafer bonding technology for compliant-substrate fabrication.

摘要

High speed optical sources at 1.3 μm are required to drive the fiber optic infrastructure around the world. Of the three components that make up an optical link, these sources limit the overall data transmission capacity of these networks. The importance of operating at 1.3 μm, has led device engineers to rely on InP-based devices, though inferior in many ways to devices based on GaAs. This work seeks to develop new device designs to improve the directly modulated bandwidths of 1.3 μm lasers.; Elevated temperatures degrade the DC and high speed performance of semiconductor lasers. InP-based devices are especially susceptible to temperature variations. Lasers were flip chip bonded to diamond heat sinks to improve heat removal from these devices. Although dramatic improvements were seen in their DC performance, the lasers' high frequency response did not improve. Other factors such, as carrier heating, likely limited the performance of these devices. Device designs on GaAs emitting at 1.3 μm were sought as a replacement for the troublesome InP devices. Laser structures employing ordered quantum wells on GaAs (111) substrates have been proposed. Theoretical calculations indicate that 1.3 μm emission should be achievable, and 1.55 μm emission may be possible. Experimental evidence from devices based on GaAs (111) indicates that such lasers should outperform their InP-based counterparts.; Lasers grown on InGaAs-like substrates, either bulk ternary or compliant substrates, are promising candidates for improving 1.3 μm device performance. In anticipation of availability of such substrates, a toolkit for designing In_xGa_1–xAs quantum well lasers on In_yGa _1–yAs substrates has been developed. The choice of well and substrate compositions, well width and desired percentage strain combinations emitting at 1.3 μm can be made using a few simple graphs. An analytical valence band model has been employed to qualitatively test competing device designs. Twist bonded compliant substrate production requires the wafer fusion of two substrates. A wafer bonding system has been designed, built and tested to improve wafer bonding techniques for this application. This machine's scalable design is capable of improved reproducibility, uniformity and yield over comparable techniques.