Packaging High Power Photodetectors for 100 MHz to 100 GHz RF Photonic Applications

ABSTRACT:In this phase II effort we will commercialize the high speed, high power, modified uni-traveling carrier (MUTC) photodiodes (PDs). To this end, we will develop reliable packaging solutions for discrete PDs, PD arrays, balanced PDs and waveguide based PDs. We will also transition the chip fabrication process for continuous, high volume supply of quality MUTC PD chips. In the first six months of phase I work we successfully packaged two prototype PD modules, and demonstrated 22GHz 3dB bandwidth and ~20dBm RF output power at 20GHz based on a 34μm-diameter diode. We have also started process development for MUTC PD chip fabrication with our own R&D funds. Based on phase I package design, we will package PD array and balanced PDs. We will also dramatically reduce the package SWaP using parallel-fed package architecture. We will collaborate with Prof. Campbell and his UVA group in developing flip-chip-comparable MUTC based waveguide PDs and diamond based chip-level integration. As a result, we will build a production family of MUTC high power PDs. We will also apply the PDs and PD modules that we developed in phase II work to related projects, such as high frequency RF generation and optical-feed phased antenna array.BENEFIT:The potential applications for high speed, high power MUTC PDs, PD array, balanced PD receiver and waveguide PDs are vast and could have a profound impact on our society. Today, as the high frequency microwave, millimeter wave and terahertz range are rapidly explored, photodiodes, especially ones with high output power, have become critical devices and indispensable ways of photonic link demodulation or high frequency signal generation. For example, generation of RF signal with enough power is very challenging, especially for very high frequency range, such as w-band. Among all the solutions, optical based methods that rely on high-frequency and high-power PDs are greatly favored due to their wide bandwidth and configurability. In addition, traditional photodiodes are made for detection of photonic input signal amplitude. A balanced PD receiver, however, is capable of detecting not only the signal amplitude, but also the phase information. As a result, a balanced PD detector is compatible with complex modulation formats such as DPSK and DQPSK. Today, as the high frequency microwave, millimeter wave and terahertz range are rapidly explored, photodiodes, especially ones with high output power and high linearity, have become critical devices and indispensable ways of photonic link demodulation or high frequency signal generation. For example, high power PD receivers have been investigated and applied for radio-on-fiber broadband wireless communications, which is propelled by the huge increase of data volume in recent years. According to Edholms law, the demand for point-to-point bandwidth in wireless short-range communications has doubled every 18 months over the last 25 years. It can be predicted that data rates of around 510Gb/s will be required in ten years. Tremendous market demands of high power PDs are expected by then. A list of potential applications of balanced high-power PD receiver includes: a) High frequency RF generation for spectroscopic applications including material detection and identification, imaging, tomography, cancer detection or genetic analysis. b) Millimeter wave wireless telecommunications. c) Long haul antenna remoting. d) Phased array antennas. e) Cable television. More specifically, PSI will commercialize the MUTC PD, PD array, balanced PD and waveguide PD to form a product family to cover high speed, high power photo detection up to 100GHz based on successful transition of the MUTC manufacturing processes and packaging process development. The commercialization process will be performed through the cooperation between PSI, UVA group and other industrial partners. PSI will seek and identify applications of high-frequency and high-power PDs in broadband phase array antennas and microwave photonic link system as a platform for multifunctional radar systems, where hundreds or thousands of PDs are required in a single system. To this end, packaged PD module with small size, light weight, low cost and easy-to-deploy interface not only represents an impressive leap forward in our technical capabilities but also a tremendous business opportunity.