• Physics and Astronomy Colloquium

September 25, 2026 3:30 PM - September 25, 2026 4:30 PM
PAIS 1100

Host:

Denis Seletskiy

Presenter:

Prof. Garrett Cole (Univ of Arizona)

This talk presents a detailed overview of advanced photonic technologies based on direct-bonded III-V semiconductor heterostructures, with a central focus on substrate-transferred crystalline interference coatings for infrared precision metrology applications. In this approach, AlGaAs-based epitaxial Bragg reflectors are directly bonded to super-polished bulk optical substrates, producing low-noise near-infrared (NIR) mirrors for cavity-stabilized lasers employed in optical atomic clocks and next-generation gravitational-wave detectors, as well as ultralow-loss mid-infrared (MIR) mirrors for cavity ring-down spectroscopy. These “semiconductor supermirrors,” first demonstrated in in 2013, uniquely combine ultralow optical and elastic losses. With continuous improvements in fabrication and metrology, crystalline coatings now routinely achieve combined scatter and absorption losses below 5 parts per million (ppm) across the NIR and MIR, spanning 940 nm to 4600 nm. This enables NIR reference cavities with record-setting stability, outperforming sputtered amorphous mirrors and powering the world’s lowest-noise laser systems. In MIR trace-gas sensing, crystalline coatings similarly surpass the detection limits achievable with PVD-deposited amorphous multilayers. Beyond passive mirrors, this bonding-based manufacturing technique supports a range of active and integrated photonic devices. Select examples include optically pumped semiconductor disk lasers for a sodium laser guide star, as well as active electro-optic and nonlinear components and photonic integrated circuits.

Bio

Garrett D. Cole completed his B.S. in materials engineering from Cal Poly SLO in 2001 and obtained his Ph.D. from UC Santa Barbara in Electronic & Photonic Materials in 2005. He subsequently held positions including the first employee of Aerius Photonics LLC (acquired by FLIR), a postdoctoral staff member at LLNL, a Marie Curie Fellow of the Austrian Academy of Sciences Institut für Quantenoptik und Quanteninformation (headed by Anton Zeilinger, Physics Nobel Laureate 2022), and a university assistant at Universität Wien Fakultät für Physik. In 2012, Prof. Cole founded Crystalline Mirror Solutions (CMS), a quantum optomechanics spin-off commercializing semiconductor supermirrors for laser-based metrology and manufacturing. CMS was successfully acquired by Thorlabs in December 2019 and rebranded as Thorlabs Crystalline Solutions. In addition to numerous startup prizes, Dr. Cole received the LIGHT2015 Young Photonics Entrepreneur Award, a Berthold Leibinger Innovationspreis (2016), an SPIE Prism Award (2017), and served as a Unesco Trust Science Champion (International Day of Light, 2021). For 2024, he was selected as a member of the Photonics100 and elected Fellow of Optica. In January 2026, he joined the Wyant College at the University of Arizona as an associate professor and the inaugural Nelson E. Claytor Endowed Chair in Optical Sciences.