chip

Acknowledgments

U.S. Government

Various projects without a separate description.

National Science Foundation

CAREER, MRI, GOALI, ECCS-EPDT, ECCS-EMPD, CISE, NIRT, ERC and Graduate Research Fellowship programs.

DoD

NDSEG Fellowship, Office of Naval Research, Air Force Office of Scientific Research.

DOE

ARPA-E.

NASA

Early Stage Innovation (ESI) Grant. NASA Space Technology Research Fellowship.

IBM

UCSD-IBM Joint Study Agreement, 2008-2011 (Dr. William M. J. Green, Thomas J. Watson Research Center, NY). IBM PhD Fellowship Award.

NIST

NSF-funded UCSD-NIST Interaction in Basic and Applied Scientific Research, 2011-2012 (Dr. Kartik Srinivasan, Center for Nanoscale Science and Technology)

IME, Singapore

Collaboration on fabrication of silicon photonic devices for nonlinear and quantum optics (Dr. X Luo, Dr. G.-Q. Lo)

Sandia National Laboratory

Collaboration on silicon photonic switches; CIAN-funded collaboration for fabrication (Dr. A. Lentine, Dr. C. DeRose).

Collaboration on hybrid silicon photonics (LDRD Grand Challenge).

University of California

UC-Lab: Laboratories Research Program, Calit-2, UCSD Senate, Hellman Fellowship.

Keysight Technologies

Optical modulators.

UTRC

Quantum technologies.

Industrial partners

Ligentec (Switzerland), Santec (USA), Luna Technologies (VA), Silicon Light Machines (CA), Optoelectronic Components (Canada), Photon Spot (CA), Single Quantum (Netherlands).

birefringence

Silicon photonics and hybrid photonics

  • [2023] 100 GHz Bandwidth, 1 Volt Near-infrared Electro-optic Mach-Zehnder Modulator. [Optica]
  • [2023] Fabrication of Hybrid TLFN Electro-optc modulators using silicon or silicon nitride waveguides. [J Phys Photonics] [JOSA B]
  • [2023] Buried-electrode Hybrid TFLN modulators. [IEEE PTL]
  • [2022] High OMA electro-optic modulation using silicon micro-resonators: 10 mW optical power handling. [Optics Express]
  • [2019] A perspective on future 3D Integrated Photonics using lithium niobate thin films. [IEEE Nanotechnology Magazine]
  • [2018] Hybrid lithium niobate Mach-Zehnder electro-optic modulator on a silicon photonics platform, exceeding 100 GHz 3-dB electrical bandwidth, co-authored with reseachers from Sandia. [Optics Express]
  • [2016] Hybrid Lithium Niobate - Silicon photonic passive devices and circuits. Back-and-forth mode transitions, bends, inter-layer coupling, interferometric circuits. [Scientific Reports]
  • [2014] Silicon photonic tunable add/drop/power control (variable optical attenuator, VOA) for four C-band WDM channels. First generation device: thermo-optic tuners on microrings, electro-optic carrier injection VOA, single polarization. [IEEE Conf. PDP]
  • [2014] Thermo-optic MZI switch with five cascaded thermo-topic phase-shifters show low power, microsecond-scale cross-bar switching of twenty wavelength channels in UCSD-MORDIA, each carrying 10 Gbit/second data concurrently. [CLEO 2014]
  • [2014] Method to extract the electronic carrier-induced loss and coupling coefficients of modern thermo-optic and electro-optic silicon MZI based 2x2 switches (Sandia, IBM and Kotura-Oracle) from the transmission spectra. [CLEO 2014]
  • [2013] Demonstrated 100 dB contrast filters (cascade of 2 chips) with 2.8 dB insertion loss, and group delay ripple < 5 ps; built using two > 50 dB extinction filters with 1.4 dB loss, and with thermally-tunable center wavelength and bandwidth (on-chip heaters) [IEEE PTL].

Nonlinear and quantum optics on a chip

QUANTUM

  • [2023] Electro-optic control of biphoton generation using hybrid photonics, using a TFLN modulator integrated with a Si photonic photon-pair source. [Optica Quantum] [CLEO 2022] post-deadline paper
  • [2021] Voltage-Controlled Fast and Low-loss Single-Photon Cross-Bar Switch Using Integrated Photonics. [Journal of Lightwave Technology] [OFC2021] post-deadline paper
  • [2019] Oscilloscopic capture of 100 GHz modulated optical waveforms using a superconducting nanowire single photon detector. [OFC 2019] post-deadline paper
  • [2019] Thin-film lithium niobate waveguide entangled photon-pair and heralded single photon generation with CAR > 67,000 and g(2)(0) < 0.025. [FIO 2019] post-deadline paper
  • [2018] Photon-pair generation using spontaneous four-wave mixing in silicon microrings, pumped using a silicon hybrid laser, co-authored with researchers from Intel. [APL Photonics] [CLEO 2017] post-deadline paper
  • [2017] Silicon photonic entangled photon-pair and heralded single photon generation with CAR > 12,000 and g(2)(0) < 0.006. [URL]
  • [2016] Pair generation at 1550 nm using only a few microwatts of optical pump power using a Si microring resonator. [Opt Express].
  • [2015] We achieve stable pair generation over 30°C temperature variation by monitoring the microring resonance using a (Ge-free) Si p-i-n photodiode as part of the ring. [Appl. Phys. Lett.].
  • [2015] Using two-photon (Franson) interferometry, we measure the entanglement of photon pairs generated from an optically-pumped silicon photonic device operated at room temperature. [Opt. Express].
  • [2014] Controlling the joint spectral intensity (2-dimensional photon spectrum) of photon pairs using a silicon chip, and varying the Schmidt degree of entanglement discretely over a wide range without beam-shaping. [Nat Commun]
  • [2013] Spectrally-multiplexed ("comb") generated by a coupled-microring silicon pair source, and temperature tuning of the wavelength [Opt Lett] [CLEO 2013 CF2M.4].
  • [2012] Heralded single photon generation from a CMOS-compatible silicon nanophotonic chip at room temperature, based on optically-pumped spontaneous four-wave mixing. [Appl Phys Lett].

    Press coverage: [NIST Tech Beat], [Photonics.com] [Optics and Photonics News]

    "Quantum Light from CMOS-compatible Silicon Microresonators" IEEE Photonics Conference paper TuW2 (2012) [invited].

    "Generating photon pairs using silicon photonics" IEEE Group IV Photonics, paper ThC.1, Paris, 27-29 August (2014) [invited].

NONLINEAR

  • [2020] Shallow-etched thin-film lithium niobate waveguides for highly-efficient second harmonic generation. [Opt. Express]
  • [2019] Periodic poling and non-destructive diagnostic techniques of x-cut thin-film lithium niobate on insulator (LNOI) for second-harmonic generation. [Opt. Express] [J. Applied Phys.]
  • [2014] Tunable higher-order microring filters were integrated on the same chip as a carrier-swept ring mixer, to separate the generated idler wavelength from the residual pump and unconverted signal [Opt Lett 2014].
  • [2013] Using reverse-biased silicon microrings, CW four-wave mixing conversion efficiency of -13.4 dB is achieved using 20 um radius micro-ring resonators with only 2.5 mW pump power [IEEE PTL 2013]. Silicon rib waveguides (passive loss of 0.74 dB/cm) with free-carrier lifetime reduction via reverse biased PIN diodes show CW four-wave mixing efficiency of -8.2 dB (-4.4 dB if both signal and idler are measured at the output) with 160 mW pump power (about 2X reduction compared to other reports in literature) [CLEO 2013].
  • [2014] Triply-resonant four-wave mixing using coupled silicon microresonators. Wavelength conversion efficiency was improved by 20 dB, enough to demonstrate open eyes at 10 Gbps for converted wavelengths using a CW pump [Opt Lett 2014]
  • [2011] Low-power CW four-wave mixing in silicon CROWs, demonstrating +16 dB conversion enhancement relative to a conventional silicon waveguide of equivalent length, a nonlinear coefficient geff=3720 /(W.m) and flat conversion in channels spanning more than 10 THz bandwidth (signal to idler) [Opt Lett 2011]. Intra-band and inter-band four-wave mixing using a continuous-wave (CW) pump in silicon CROWs [CLEO].
  • [2010] Four-wave mixing in silicon waveguides at wavelengths above 2 um, demonstrating a nonlinear coefficient g=103 /(W.m) and flat conversion over more than 220 nm bandwidth (signal to idler) [Nat Photon] [Frontiers in Optics, 2009]
  • [2010] Two pump four-wave mixing in silicon waveguides, showing multicasting of a pulsed signal into several idler wavelengths [Fronters in Optics, 2010].

Coupled micro-resonators: science and applications

  • [2014] Electronic on-off switching control over optical Anderson localized modes using a lithographically-fabricated silicon photonic waveguide infiltrated by about 100 sub-micron-scale p-n junction diodes. [Nat Nano]
  • [2010] Silicon microring coupled-resonator optical waveguides (CROWs) consisting of upto 235 coupled microring resonators [Opt Lett].
  • [2010] Statistical measurements of intensity and group delay, showing scaling behavior with length, and evidence of non-localized propagation through 235-ring silicon CROWs [OpEx].
  • [2007] Effect of disorder on slow-wave waveguides, deriving a simple expression for the maximum achievable slowing factor (S=c/vg) [Opt Lett].
  • [2011] How many rings can be coupled in a CROW before disorder-induced bandwidth collapse occurs? Theoretical and experimental studies in silicon microring CROWs [Opt Lett].
  • [2008] Light localization in SOI coupled resonator optical waveguides, demonstrating strong localization of Bloch excitations in a disordered 1D chain of 100 resonators [Nat Photon].
  • [2011] Accurate transfer matrix modeling of long CROWs, including silicon waveguide dispersion and disorder effects [PTL].
  • [2014] 20 dB improvement in CW four-wave mixing in silicon CROWs with electronic free-carrier removal [Opt Lett]
  • [2001-2004) Earlier tight-binding [OpEx, 2001] and transfer-matrix analysis [OpEx, 2004] of CROWs. Tight-binding analysis of holographic pulse storage in CROWs [PRE, 2001]. Nonlinear interactions in CROWs [PRE, 2002]. "Frozen" light CROW soliton theory [PRE, 2002].

Experimental and theoretical methods

  • [2020] Full-Speed Testing of Silicon Photonic Electro-Optic Modulators from Picowatt-level Scattered Light. [OFC 2020] post-deadline paper
  • [2019] Oscilloscopic capture of 100 GHz modulated optical waveforms at femtowatt power levels. [OFC 2019] post-deadline paper
  • [2012] Static rerouting of the optical light path on a silicon chip, using tip-induced nano-oxidation of 2x2 components: microring add/drop filter and Mach-Zehnder interferometer [CLEO/QELS 2012].
  • [2011] 0.002 nm precision set-and-forget alignment of silicon photonic microring resonators and Mach Zehnder interferometers using nano-oxidation [OFC PDP, 2011] and [Opt Lett]
  • [2011] Measuring statistical distributions of group delay in silicon nanophotonic waveguides rapidly and accurately using the Luna OVA5000 and unfiltered optical amplification [IEEE PTL].
  • [2010] Infrared imaging and diagnostics of multi-resonator optical circuits, extracting individual resonator eigen-frequencies and coupling coefficients in a rapid and non-invasive way [Opt Lett].
    Spotlight on Optics, commentary by Dr. J. E. Heebner.
  • [2012] High dynamic range infrared microscope imaging of silicon nanophotonic devices, overcoming conventional signal-to-noise ratio limitations in dB-scale imaging, by stitching together several images taken at different integration time, using a commercial 12-bit InGaAs infrared (1550 nm wavelength) camera [Opt Lett].
  • [2009] Numerically-assisted coupled mode theory for more accurate design of strongly-coupled and compact silicon-on-insulator waveguide couplers and waveguide arrays [OpEx].

Other work in chip-scale photonics

  • [2008] Giant birefringence in multi-slot SOI waveguides. We demonstrate record giant birefringence, nearly twice as large as has previously been achieved (Dngroup = 1.5 over more than 60 nm of bandwidth near 1550 nm) using a multi-slotted silicon nanophotonic waveguide [OpEx].
  • [2006] Microfluidically-tuned polymeric microring resonator with microfluidic chip for sensing small changes in fluidic composition by refractive index monitoring of a flow [Appl Phys Lett]. This work was one of the earliest "opto-fluidic" micro-resonator demonstrations.