// // //

Research Overview

We are interested in nanophotonic device concepts and circuit design motivated by challenges in system level applications in areas including telecommunications, on-chip interconnects, sensing and imaging, energy conversion and control, and classical and quantum computation and information processing. We are generally interested in first-principles innovation in device design using new physical principles in photonics as well as at the interface of nanophotonics, nanomechanics, solid-state and quantum electronics, and other fields. Our research involves rigorous theory and design of novel devices and concepts, and the experimental study and characterization of fabricated proof-of-concept device chips. For more information see research.


Jan 2015 - If you are interested in the latest developments in our research, Prof. Popovic will be giving invited talks at four upcoming conferences: SPIE Photonics West 2015 (February 10, San Diego, USA), the IEEE Summer Topical Meeting on On-Chip Optical Interconnects (July 2015, Nassau, Bahamas), Photonica 2015 (August 25, Belgrade, Serbia), and IEEE Group IV Photonics Conference (August 28, Vancouver, Canada).

Sep 2014 - Monolithic CMOS electronics-photonics integration: Together with collaborators at Berkeley and MIT, we have recently demonstrated the integration of electronics and photonics on the same chip on the largest scale by far to date, with over 70 million transistors and 1000 photonic devices, including two state-of-the-art, functional, RISC V vector-core microprocessors. The most recent results demonstrated record efficiency (20 fJ/bit) photonic transmitters and the first infrared receivers in unmodified, sub-100nm, monolithic CMOS technology (paper C83). We also demonstrated the first optical link between two bulk CMOS chips (papers C84, J36), and our collaborators from Micron Technology described our joint work on a photonics platform in a bulk CMOS memory foundry process (paper C82) -- work that was used to publicize the VLSI Symposia on Technology. Our unique approach to photonics integration is making possible very rapid progress toward very large scale integration. In addition, we have recently published work demonstrating that our monolithic CMOS photonics integration paradigm provides high performance photonic devices: high efficiency "array nanoantenna" fiber-to-chip couplers (paper C86), record tuning efficiency resonators and highly efficient modulators (paper C80). And, we have begun to demonstrate broad capabilities in monolithic CMOS photonics, including four-wave mixing, and photonic crystal microcavity geometries enabling ultra-low loss cascadable filters for the first time (paper C92)

Sep 2014 - Parametric oscillators and frequency combs: We have recently published papers on the optimum design of Kerr parametric oscillators (paper J31) and novel realizations there of, as well as on a general coupled-mode approach to dispersion compensation in resonant four-wave mixing -- a general problem in parametric oscillators and comb generation (paper J34). Finally, we have presented a new, all-order approach to dispersion design in microcavities -- an important issue in four wave mixing and comb design (paper C93).

May 2014 - Imaginary coupling makes waves: We have taken the concept of imaginary coupling (see original papers C29 and C55) in new directions using both spatial and temporal versions of the concept. Spatial: after the demonstration of record-efficiency waveguide crossings (paper J29) using an optical field whose photons change their spatial wavefunction to avoid scatterers, we demonstrated a new, circular wiggler-mode microcavity with high Q that uses a similar principle (paper J32). Temporal: we have proposed a new type of laser resonator that we called a dark state laser (paper J33) -- it is a novel geometry, alternative to the classic Littman-Metcalf and Littrow external cavity laser configurations for achieving single-frequency, mode-hop free tunable laser operation. An industrial research collaboration is under way to demonstrate this new type of source.

Apr 2014 - Three papers will be presented at the VLSI Symposia in Technology (1 paper) and Circuits (2 papers). The conference has highlighted some of our work in a press release, citing that, "The potential to use silicon photonics as a memory interconnect technology will be demonstrated." VLSI takes place this summer, June 9-13.

Apr 2014 - Congrats to Jelena Notaros for taking first place at the IEEE Region 5 Conference paper competition for her work, Complex Wavevector Bloch Solver for Nanophotonic Device Applications. Jelena was congratulated by IEEE International President Roberto de Marca and IEEE USA President Jim Jefferies.

Feb 2014 - Optical Fiber Communication conference (OFC) has recently publicized our upcoming invited talk on energy efficient photonic in zero change advanced CMOS, to be given by graduate student Mark Wade. The story received further recognition on Photonics.com, Laser Focus World, R&D Magazine, and LightWave Online.

Feb 2014 - Graduate student Mark Wade gave a talk at Photonics West, February 3, on Spoked-ring microcavities: enabling seamless integration of nanophotonics in unmodified advanced CMOS microelectronics chips.

Dec 2013 - Congrats to Chris Poulton, selected as a plenary speaker at the NCRC undergraduate research conference to be held at Harvard in January 2014.

Oct 2013 - Our recent modulator work has received expansive press attention, including phys.org, photonics.com, hpcwire.com, extremetech.com, and colorado.edu.

                    Prof. Popovic also gave an interview this month on the Brian Lehrer show.

Aug 2013 - Prof. Popovic will be giving an invited talk on silicon nonlinear and quantum photonics at the OSA Frontiers in Optics (FiO) Conference in Orlando in October, and a talk on energy efficient monolithic electronic-photonic circuits at Photonics West in January 2014. Prof. Popovic will also present our group's work at the Packard Fellows Meeting in Denver, Colorado, Sep 11-14, 2013.

Aug 2013 - We have three new postdoc positions open in CMOS photonics, optomechanics and nonlinear photonics, respectively. Job descriptions: CMOS(pdf), Optomechanics(pdf) and Nonlinear/Quantum(pdf).

Aug 2013 - We have contributed to a review of the fundamental requirements to achieve optical isolation, in Nature Photonics. This follows a Workshop on Optical Isolators at IPR in July 2013, co-presided by Prof. Popovic and Prof. Shanhui Fan of Stanford University. The workshop was successful, and the invited speakers' summarized talks will be posted on a webpage for broader access.

July 2013 - Our team, lead by postdoc Jeff Shainline and graduate students Mark Wade and Kareem Nammari, in collaboration with colleagues at MIT and Micron, has achieved back to back breakthroughs in monolithic silicon photonic interconnects, demonstrating the first depletion-mode modulators in unmodified SOI CMOS, as well as the first depletion mode polysilicon modulators. These results show for the first time designs that could be built into the state of the art microelectronics, like the IBM Power7 microprocessor, today -- and, into bulk CMOS processes that constitute 90% of state of the art microelectronics. The papers appear in the August 1 issue of Optics Letters under Optoelectronics.

July 2013 - Our group has presented four papers at Integrated Photonics Research (IPR) 2013. Two describe advances in our 45nm SOI CMOS photonics platform including Mark Wade's work demonstrating pole-zero filters for maximizing optical bandwidth density, and Chris Poulton's undergraduate research demonstrating the first photonic crystal cavities in zero-change CMOS. Yangyang Liu demonstrated structures using a novel type of loss-coupled Bloch wave to demonstrate record low waveguide crossing losses <0.04dB/crossing (<1%/crossing); in a second paper, she demonstrated contacted circular "wiggler" cavities, with applications in active devices and optomechanics.

June 2013 - Our group welcomes undergraduate student Emily Donahue from Cornell University, who is pursuing a nanofabrication based NSF NNIN REU project in our lab over a course of 9 weeks.

June 2013 - Congrats to Chris Poulton, an undergraduate researcher in our group, for winning a Tau Beta Pi scholarship. Congrats to Juan Llinas, former NSF REU undergraduate researcher in our group, for winning two prestigious scholarships at UIUC: the Schlander Memorial Scholarship and the Paul E Parker award.

June 2013 - Our group has presented four papers at CLEO 2013, including Xiaoge Zeng's work on optimum design of parametric oscillators, Cale Gentry's proposal of "dark state lasers", and Jeff Shainline's work demonstrating high-Q contacted "wiggler" microcavities, and using them to demonstrate the first polysilicon depletion modulators.

Apr 2013 - Congratulations to undergraduate researcher Chris Poulton, who won a Best Paper award at the Discovery Learning Apprenticeship (DLA) student conference with his work on photonic crystal cavities in zero-change advanced CMOS. See DLA Website for more information.

Jan 2013 - Our group presented five papers at the Union of Radio Science International (URSI) National Radio Science Meeting in Boulder, Colorado. Savvy presented on optimum parametric oscillator designs, Yangyang on novel, circular "wiggler" resonators, Mark on pole-zero filter design, Kareem on unidirectional grating couplers, and Chris on photonic crystal resonators in advanced CMOS.

Dec 2012 - We have contributed to a critique, published in this month's issue of Science, of recent work claiming Lorentz reciprocity violation in non-magnetic, time-invariant structures.

Nov 2012 - Miljan Dasic, an undergraduate researcher in our group, has won a Best Paper award at the IEEE Student Projects Conference (IEEESTEC) in Nis, Serbia. See award here and news here.

Aug 2012 - Daniel Klemme, former NSF REU undergraduate researcher in our group will begin graduate studies at the University of British Columbia in the fall.

Oct 2012 - We have three postdoc positions open - in CMOS photonics, optomechanics and nonlinear photonics, respectively.
Job descriptions: CMOS(pdf) and Optomechanics/nonlinear(pdf)

Oct 2012 - Prof. Popovic is named a Fellow of The Lucile & David Packard Foundation (CU press release, Packard announcement). The fellowship brings our laboratory an unrestricted research grant of $875,000 over five years to make advances in optomechanics and nonlinear photonics.

Oct 2012 - Dr. Jeffrey Shainline is awarded an NRC Fellowship. He will continue research on quantum photonics in collaboration with our group at NIST Boulder.

May 2012 - Cale Gentry and Mark Wade are awarded CU-NIST Measurement Science and Engineering Fellowships.

Jan 2012 - Our paper demonstrating the first photonic transmitter in advanced CMOS is published in Optics Express.

Aug 2011 - Our group, with collaborators at MIT, Berkeley and Micron Technology, is awarded a $15M research grant as part of the DARPA POEM program to develop energy-efficient microphotonic CPU-to-memory interconnects built entirely in native advanced CMOS - both bulk Si (DRAM) and thin SOI (logic). (Darpa announcement)

Dual-microring nanophotonic light-force system (photo)
Dual-microring resonator nanophotonic system designed to trap nanomechanical movable parts using light forces (paper J12).

Loop-coupled resonator concept (photo)  First loop-coupled resonator filter (photo)
Loop-coupled resonator concept enabling optimal filters and first device, (papers C18, C28).

Resonant nanophotonic hitless switch (photo)
First truly hitless (dispersionless) resonant switch, (paper C20).

Silicon nanophotonic circuit on a chip (photo)
Silicon nanophotonic circuit chip with wirebonded controls (papers C20-C22).

Low-loss Bloch-wave based waveguide crossing array (photo)
Ultra-low-loss waveguide crossing array for on-chip photonic interconnect based on low-loss Bloch wave concept (paper C23).