"UCSB Nanotech Tech Talks | Milan Mashanovitch, Freedom Photonics LLC & Brian Romanczyk, UCSB"

Milan Mashanovitch, Freedom Photonics & Brian Romanczyk, UCSB,

October 10th (Thursday), 12:00pm
Engineering Science Building (ESB), Rm 1001

“Photonic Devices for Optical Sensing”
Dr. Milan Mashanovitch, Freedom Photonics”

Abstract: Optical sensing is a rapidly growing field, with applications spanning facial recognition, LIDAR, gas sensing, structural health monitoring, RF signal detection and optical processing. In this presentation, we will focus on unique novel photonic components for gas sensing and for optical RF signal detection and processing recently developed by Freedom Photonics. These applications pose very stringent performance requirements on the respective components. For gas sensing, optical power, linewidth and tuning speed are key. For RF photonics, additional parameters such as linearity and operating bandwidth are critical. In the first part of the talk, we will discuss our recently developed fast-tunable high-power laser sources for methane detection within an integrated path differential absorption LIDAR flight instrument. These tunable laser exhibit 200mW of output power, with nanosecond tuning times, which allow quick scanning of the absorption lines of the gas.

The other topic of the talk will be our high-power, high-performance laser sources and photodetectors for RF photonic systems. Our current generation of lasers produces 400mW of single mode output power, with RIN of -165 dBc/Hz, and 50 KHz linewidth. The high-power photodiodes developed can detect RF powers of 23 dBm for operation at 25 GHz, with high linearity, and operate all the way up to 110 GHz.

“N-Polar GaN HEMTs for mm-Wave Power Amplification”
Brian Romanczyk, UCSB

Abstract: Gallium Nitride high electron mobility transistors (GaN HEMTs) are proven to be well suited devices for highly efficient solid-state radio frequency power amplification, especially when high output power is desired. Existing GaN transistor technologies using the Ga-polar crystal orientation (0001) have been demonstrated operating at millimeter‑wave frequencies (30 to 300 GHz). While these Ga‑polar devices have demonstrated good large signal functionality, their performance has largely saturated. With growing interest in communication and imaging applications operating at mm‑wave frequencies there is a need for transistors technologies with higher performance at these frequencies. This work focuses on the development and demonstration of mm-wave N‑polar GaN HEMTs using a deep recess device structure. The internal polarization electric fields that are characteristic of c-plane GaN are inverted in the N‑polar GaN orientation (000-1) relative to the Ga‑polar orientation. This enables the deep recess device structure used in this work where a GaN cap layer is added into the access regions of the device. This GaN cap mitigates the impact of DC‑to‑RF dispersion and improves the conductivity of the access regions leading to the demonstration record‑high output power density and power‑added efficiency at operating frequencies ranging from 30 to 94 GHz. At 94 GHz, an unprecedented 8 W/mm of output power density with an associated 26.9% power-added efficiency has been obtained.

About Milan Mashanovitch, Freedom Photonics & Brian Romanczyk, UCSB:

Mashanovitch Biography: Dr. Milan Mashanovitch co-founded Freedom Photonics and he is currently the Company’s CEO. Dr. Mashanovitch has 20 years of experience working in the field of photonics, spanning over design, fabrication, testing and packaging of photonic integrated circuits, combined with 10 years of management and business development experience. Dr. Mashanovitch holds a dipl. ing. Degree in Electrical Engineering from the University of Belgrade in Serbia, and M.S. and Ph.D. degrees from the University of California in Santa Barbara. Mashanovitch has co-authored over 150 papers, many invited, on photonic integrated circuits and various photonic devices. He holds 9 patents, and has co-authored the second edition of the “Diode Lasers and Photonic Integrated Circuits” textbook. He is very active in the photonics technical community, participating on technical committees of many conferences. He is a Senior Member of IEEE.

Romanczyk Biography: Brian Romanczyk graduated from Rochester Institute of Technology with B.S. and M.S. degrees in microelectronic engineering in 2012 and 2013. There he was involved with several research projects focused on the fabrication of Esaki tunnel diodes and tunnel FETs. While at RIT he also held internship positions at Northrop Grumman working on GaAs HBT fab and at HRL Laboratories working on improving fabrication processes for InP HBTs and silicon photonic devices. Since then, Brian has been with the Mishra Research Group at UCSB where he obtained his Ph.D. in 2018 and is currently a postdoctoral researcher examining N-polar GaN HEMTs for mm-wave power applications.

Hosted by: Professor Jonathan Klamkin