Integrated Photonics

I am interested in using integrated photonic technology to miniaturize optical components for space applications such as astronomical instrumentation, remote sensing, and laser communications. My PhD research was conducted with the Integrated Nanosystems and Quantum Information group at MIT Lincoln Laboratory on photonic component design and demonstration (Lumerical/MATLAB/Python).  

My PhD thesis developed a Germanium-on-Silicon integrated photonics platform for the mid-wave infrared (2-5 um) wavelength range. Most integrated photonics development occurs in the near-infrared telecommunication wavelength bands using the silicon-on-insulator (SOI) platform, but this platform cannot be used at wavelengths longer than 4 um because of material absorption. This thesis seeks to advance the state of the art in mid-wave infrared integrated photonics for applications such as atmospheric and chemical sensing, which use mid-wave infrared light to detect a large number of spectral features in the "fingerprint" region. 

The Germanium-on-Silicon platform has been used to demonstrate low-loss waveguides and ring resonators at 4.6 um (link to CLEO paper). The figures below show rectangular and rib waveguide designs (left), SEM imagery of fabricated devices (center), and an example transmission spectrum from a ring resonator demonstration (right). I also designed integrated plasma dispersion effect modulators and thermal phase shifters for this platform. 

I've also contributed to photonic device design and measurements for trapped-ion atomic clock and quantum computing projects at Lincoln Laboratory (link to paper on photonics for trapped-ion projects). These projects use integrated photonics to route many wavelengths spanning the UV, visible, and infrared in order to miniaturize optical setup footprints from the size of an optical table onto a photonic chip about the size of a quarter. I have worked on designs of grating couplers in nitride to direct light off of the photonic chip and focus it at the trapped ion location. I developed a Bragg-grating optimization approach that can be applied to many wavelengths quickly (Lumerical). I have also applied inverse design methodology to the design of grating couplers and tapers for this project (Lumerical/Python). 

I also characterized silicon detectors integrated with alumina and nitride waveguides for blue, red, and infrared wavelengths (link to IPC paper on blue light detectors). This is one of the first demonstrations of a waveguide-integrated photodetector for blue wavelengths. The figures below show the laboratory testing setup (left) and a sample of lab data (center/right) including detector responsivity measurements and IV curves.

Deformable Mirror Demonstration Mission (DeMi)

In graduate school, I worked on the Deformable Mirror Demonstration Mission (DeMi) CubeSat mission. The DeMi payload demonstrated a Microelectromechanical Systems (MEMS) deformable mirror on-orbit for the first time. Deformable mirrors are used to correct wavefront errors in optical systems, and are a critical component of a coronagraphic exoplanet direct imaging instrument. MEMS DMs are a promising technology option for space telescope coronagraph instruments due to their small size and low power requirements. 

I worked on optical alignment (using a Zygo interferometer), optical diffraction modeling (Python) and laboratory testing of the DeMi optical payload, as well as camera driver development (C/C++), and operations code development (Ruby/COSMOS). I lead a team of 8 graduate students in payload integration into the spacecraft, environmental testing, and on-orbit operations for the mission. The pictures below show various stages of DeMi payload integration into the spacecraft.

DeMi launched to the ISS in February 2020 and operated in space from July 2020 - March 2022.  I personally commanded >400 satellite overpasses from 5 different states! This project demonstrated a key technology for future exoplanet direct imaging space telescopes. The plot below summarizes the results from our on-orbit wavefront control experiments, successfully using a MEMS deformable mirror to reduce the optical payload wavefront error in space from ~450 nm to <100 nm RMS! 

For more information on the DeMi mission, please refer to these publications: 

- Morgan R., Vlahakis S., Douglas E., et al. "On-Orbit Operations Summary for the Deformable Mirror Demonstration Mission (DeMi) CubeSat." Proceedings of SPIE Astronomical Telescopes and Instrumentation 12185 2022. (link to proceedings). 

- Morgan R., Douglas E., Allan G., et al., “Optical calibration and first light for the deformable mirror demonstration mission CubeSat (DeMi).” Journal of Astronomical Telescopes and Instrument Systems 7 (2) 2021. doi: 10.1117/1.JATIS.7.2.024002 (link to article)

-Morgan R., Douglas E., Allan G., et al., “MEMS Deformable Mirrors for Space-Based High Contrast Imaging.” Micromachines 10 (6), 366, 2019. (Link to article)

Exoplanet detection and characterization 

As an undergraduate researcher, I worked on reducing data from the Magellan Adaptive Optics (MagAO) instrument using the Karhunen-Loeve Image Processing (KLIP) post-processing technique (Python) (link to SPIE proceedings), which improves the contrast of images by applying SVD to subtract residual starlight. The right figure below shows data from the MagAO adaptive optics instrument that has been post-processed and includes injected artificial planets that are used to correct the detection contrast curves shown on the right to account for the throughput of the subtraction algorithm. 

Free Space Laser Communications

As an undergraduate researcher at MIT, I worked on optical design, link budget analysis (MATLAB), and prototyping for a CubeSat laser communications crosslink system for the Cubesat Lasercom Infrared CrosslinK (CLICK) project (link to SmallSat Conference paper). Laser communications can provide high data rate transmissions with instruments that are smaller, less expensive, less regulated, and require less power compared to radio frequency systems. 

In undergrad, I also worked on the Nanosatellite Optical Downlink Experiment (link to NODE paper). I developed optical setups to test pointing algorithms with MEMS Fast Steering Mirrors, conducted link budget analysis (MATLAB), and worked on retrofitting a commercial amateur telescope to use as a ground station. 

I spent three summers as an intern at the NASA Jet Propulsion Laboratory in the Optical Communications and Systems Engineering groups (2016-2018). I worked on analyzing atmospheric scintillation data for the Table Mountain Facility optical ground station and concept of operations/requirements development for the Deep Space Optical Communications payload, which is part of the Psyche mission and in 2023 successfully demonstrated an optical communications link from Mars orbital distance!