High-power flip-chip mounted photodiode array

Allen S Cross,Yang Fu,Qiugui Zhou,Joe C Campbell,Andreas Beling

doi:10.1364/oe.21.009967

Abstract

Four-element modified uni-traveling-carrier (MUTC) photodiode arrays (PDA) flip-chip bonded onto transmission lines on AlN substrates are demonstrated. High RF output powers of 26.2 dBm and 21.0 dBm are achieved at 35 GHz and 48 GHz, respectively, using a PDA with 28-μm diameter photodiodes. A systematic comparison between a PDA with four 20 μm-diameter elements and a discrete detector with the same active area (40-μm diameter) is presented. The PDA achieved higher output power and thermal dissipation compared to its discrete counterpart.

Highlights

As optical communication networks accumulate consumers with ever increasing demands, there will be a continuous need for greater capacity and functionality from these networks
Four-element modified uni-traveling-carrier (MUTC) photodiode arrays (PDA) flip-chip bonded onto transmission lines on AlN substrates are demonstrated
High RF output powers of 26.2 dBm and 21.0 dBm are achieved at 35 GHz and 48 GHz, respectively, using a PDA with 28-μm diameter photodiodes

Summary

Introduction

As optical communication networks accumulate consumers with ever increasing demands, there will be a continuous need for greater capacity and functionality from these networks. Improvements in one performance parameter of a detector are often achieved at the expense of one or more significant figures of merit. The detector bandwidth, which is determined by a combination of resistance-capacitance (RC) time-constant and carrier transit time limitations, has a more complicated but typically inverse relationship to the physical dimensions. While connecting detectors in parallel can produce higher saturation currents and greater RF output powers, the capacitances are cumulative and, once again, limit bandwidth. In this paper we study the performance of a flip-chip bonded photodiode array (PDA) with four normal-incidence backilluminated PD-elements and a travelling wave transmission line design

Epitaxial structure

Chip fabrication

Submount integration

Frequency domain characterization

Frequency dependence

Current dependence of RF output