Thermal Analysis of InP Lasers Transfer Printed to Silicon Photonics Substrates

Abstract

The thermal performance of Fabry-Perot InP lasers integrated onto different silicon photonics substrates by microtransfer printing is assessed. 500-μm-long ridge waveguide lasers on the original 350-μm-thick InP have an experimental thermal impedance, ZEXP, of 57 K/W that is reduced to 38 K/W after printing to a 500-μm-thick Si substrate. ZEXP for lasers printed on silicon-on-insulator wafers is ~94 K/W, which is more than two times higher than that of the laser printed on the Si substrate. ZEXP of lasers printed on thermally insulating layers like benzocyclobutene (BCB) or SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> increases with the thickness of the layer. BCB adhesive layers as thin as 50 nm limit ZEXP to be greater than 55 K/W. The thermal properties for the different situations were modeled using finite-element simulations which confirmed the experimental results within 10% accuracy. The simulations show how changes in the geometry and the materials of the integration platform can influence the resulting thermal impedance.