Publications

2011
Xu, Lin, Wenjia Zhang, Hugo L. R. Lira, Michal Lipson, and Keren Bergman. “A hybrid optical packet and wavelength selective switching platform for high-performance data center networks.” Optics Express 19 (2011): 24258-24267. Abstract
We propose and experimentally demonstrate for the first time a hybrid optical packet and wavelength selective switching platform for high-performance data center networks. This architecture based on cascaded silicon microrings and semiconductor optical amplifiers (SOAs) supports wavelength reconfigurable packet and circuit switching, and is highly scalable, energy efficient and potentially integratable. By combining the wavelength-selective behavior of the microring and the broadband behavior of the SOA switch, we are able to achieve fast switching transitions, high extinction ratios, and low driving voltages, which are all requirements for future optical high-performance data center networks. Routing correctness and error-free operation (<10(-12)) are verified for both 10-Gb/s and 40-Gb/s packets and streaming data with format transparency. (C) 2011 Optical Society of America
Xu, Lin, Kishore Padmaraju, Long Chen, Michal Lipson, and Keren Bergman. “10-Gb/s Access Network Architecture Based on Micro-Ring Modulators With Colorless ONU and Mitigated Rayleigh Backscattering.” IEEE Photonics Technology Letters 23, no. 13 (2011): 914-916. Abstract
We demonstrate an optical access network architecture utilizing the wavelength-selective behavior of micro-ring modulators to achieve single-sideband (SSB) modulation, which generates a downstream signal and simultaneously provides a centrally distributed carrier for upstream phase-remodulation. Cascaded silicon micro-rings are capable for complementary metal-oxide-semiconductor (CMOS) integration and multichannel SSB modulations which can help to significantly reduce the cost of the wavelength-division-multiplexed (WDM) passive optical networks (PONs). We further study the power penalty induced by Rayleigh backscattering from the centrally distributed carrier and show a power penalty of less than 0.6 dB when propagating 43 km of a single feeder fiber.
10-gbps_access_network_architecture_based_on_micro-ring_modulators_with_colorless_onu_and_mitigated_rayleigh_backscattering.pdf
Olaosebikan, Debo, Selcuk Yerci, Alexander Gondarenko, Kyle Preston, Rui Li, Luca Dal Negro, and Michal Lipson. “Absorption bleaching by stimulated emission in erbium-doped silicon-rich silicon nitride waveguides.” Optics Letters 36, no. 1 (2011): 4-6. Abstract
Stimulated emission from sensitized erbium ions in silicon-rich silicon nitride is demonstrated by pump-probe measurements carried out in waveguides. A decrease in the photoinduced absorption of the probe at the wavelength of erbium emission is observed and is attributed to stimulated emission from erbium excited indirectly via localized states in the silicon nitride matrix. (C) 2010 Optical Society of America
absorption_bleaching_by_stimulated_emission_in_erbium-doped_silicon-rich_silicon_nitride_waveguides.pdf
Wen, Henry, Onur Kuzucu, Taige Hou, Michal Lipson, and Alexander L. Gaeta. “All-optical switching of a single resonance in silicon ring resonators.” Optics Letters 36, no. 8 (2011): 1413-1415. Abstract
We theoretically investigate a wavelength-selective all-optical switch using Raman-induced loss in a silicon resonator add-drop filter. We show that picojoule control pulses can selectively modulate and "erase" a single cavity resonance from full extinction to greater than 97% transmission while leaving adjacent resonances undisturbed. Full switching is achievable in less than 300 ps with only a few hundred femtojoule energy dissipation. This represents, to our knowledge, the first scheme for selective modulation of single resonances of an optical cavity. (C) 2011 Optical Society of America
all-optical_switching_of_a_single_resonance_in_silicon_ring_resonators.pdf
Wen, Y. Henry, Onur Kuzucu, Taige Hou, Michal Lipson, and Alexander L. Gaeta. “All-optical switching of a single resonance in silicon ring resonators.” Optics letters 36, no. 8 (2011): 1413-5. Abstract
We theoretically investigate a wavelength-selective all-optical switch using Raman-induced loss in a silicon resonator add-drop filter. We show that picojoule control pulses can selectively modulate and "erase" a single cavity resonance from full extinction to greater than 97% transmission while leaving adjacent resonances undisturbed. Full switching is achievable in less than 300 ps with only a few hundred femtojoule energy dissipation. This represents, to our knowledge, the first scheme for selective modulation of single resonances of an optical cavity.
all-optical_switching_of_a_single_resonance_in_silicon_ring_resonators.pdf
Wiederhecker, Gustavo S., Sasikanth Manipatruni, Sunwoo Lee, and Michal Lipson. “Broadband tuning of optomechanical cavities.” Optics Express 19, no. 3 (2011): 2782-2790. Abstract
We demonstrate broadband tuning of an optomechanical microcavity optical resonance by exploring the large optomechanical coupling of a double-wheel microcavity and its uniquely low mechanical stiffness. Using a pump laser with only 13 mW at telecom wavelengths we show tuning of the silicon nitride microcavity resonances over 32 nm. This corresponds to a tuning power efficiency of only 400 mu W/nm. By choosing a relatively low optical Q resonance (approximate to 18,000) we prevent the cavity from reaching the regime of regenerative optomechanical oscillations. The static mechanical displacement induced by optical gradient forces is estimated to be as large as 60 nm. (C) 2011 Optical Society of America
broadband_tuning_of_optomechanical_cavities.pdf
Lira, Hugo L. R., Carl B. Poitras, and Michal Lipson. “CMOS compatible reconfigurable filter for high bandwidth non-blocking operation.” Optics Express 19, no. 21 (2011): 20115-20121. Abstract
We design, fabricate and characterize a CMOS-compatible, Mach-Zehnder-coupled, second-order-microring-resonator filter with large Free Spectral Range and demonstrate non-blocking thermo-optical filter reconfiguration. The device consists of 10-mu m radius silicon microring resonators, with an FSR equivalent to that of a structure consisting of 5-mu m radii microrings. The structure is reconfigurable over an 8.5 nm range without blocking other channels in the network. (C) 2011 Optical Society of America
cmos_compatible_reconfigurable_filter_for_high_bandwidth_non-blocking_operation.pdf
Ophir, Noam, Johnnie Chan, Kishore Padmaraju, Aleksandr Biberman, Amy C. Foster, Mark A. Foster, Michal Lipson, Alexander L. Gaeta, and Keren Bergman. “Continuous wavelength conversion of 40-Gb/s data over 100 nm using a dispersion-engineered silicon waveguide.” IEEE Photonics Technology Letters 23, no. 2 (2011): 73-75. Abstract
We demonstrate broadband continuous wavelength conversion based on four-wave mixing in silicon waveguides, operating with data rates up to 40 Gb/s, validating signal integrity using bit-error-rate measurements. The dispersion-engineered silicon waveguide provides broad phase-matching bandwidth, enabling complete wavelength-conversion coverage of the S-, C-, and L-bands of the International Telecommunication Union (ITU) grid. We experimentally show this with wavelength conversion of high-speed data exceeding 100 nm, and characterize the resulting power penalty induced by the wavelength conversion process. We then validate the bit-rate transparency of the all-optical process by scaling the data rate from 5 Gb/s up to 40 Gb/s at the 100-nm wavelength conversion configuration, showing consistent low power penalties, validating the robustness of the four-wave mixing process in the silicon platform for all-optical processing.
continuous_wavelength_conversion_of_40-gbps_data_over_100_nm_using_a_dispersion-engineered_silicon_waveguide.pdf
Robinson, Jacob T., and Michal Lipson. “Direction-dependent optical modes in nanoscale Silicon waveguides.” Optics Express 19, no. 19 (2011): 18380-18392. Abstract
We show that in high-index-contrast nanoscale waveguides counter propagating waves can posses distinct spatial near-field profiles. Using transmission-based near-field scanning optical microscopy (TraNSOM), we identify and map the unique near-field intensity distributions of these counter-propagating modes in a single-mode silicon waveguide. Based on this phenomenon, we design and simulate an integrated device 45 mu m in length that selectively attenuates reflected light with an insertion loss of -3.6 dB and an extinction of greater than -20 dB. (C) 2011 Optical Society of America
direction-dependent_optical_modes_in_nanoscale_silicon_waveguides.pdf
Xu, Lin, Johnnie Chan, Aleksandr Biberman, Hugo L. R. Lira, Michal Lipson, and Keren Bergman. “DPSK Transmission Through Silicon Microring Switch for Photonic Interconnection Networks.” IEEE Photonics Technology Letters 23, no. 16 (2011): 1103-1105. Abstract
We experimentally demonstrate for the first time switching of differential-phase-shift-keyed (DPSK) signals through a silicon photonic electrooptic microring switch. DPSK format has been shown to be robust to nonlinear effects, and has 3-dB improved receiver sensitivity with balanced detection compared to the on-off-keyed format. Moreover, an extension to multilevel phase-shift-keyed (PSK) format enables higher data bandwidth. Packetized transmissions of single-and multichannel 10-Gb/s DPSK signals are demonstrated. Error-free transmission and power penalties of less than 1.7 dB are achieved for all the examined wavelength channels, confirming format transparency of the microring switch for PSK format, and validating the use of DPSK signaling for photonic interconnection networks.
dpsk_transmission_through_silicon_microring_switch_for_photonic_interconnection_networks.pdf
Djordjevic, Stevan S., Lian Wee Luo, Salah Ibrahim, Nicolas K. Fontaine, C. B. Poitras, Binbin Guan, Linje Zhou, et al.. “Fully Reconfigurable Silicon Photonic Lattice Filters With Four Cascaded Unit Cells.” IEEE Photonics Technology Letters 23, no. 1 (2011): 42-44. Abstract
We present a fully reconfigurable optical filter built by cascading four identical unit cells. The devices are fabricated using two distinct methods: a complementary metal–oxide–semi-conductor (CMOS) compatible process utilizes deep ultraviolet (DUV) lithography with tuning elements defined by ion implantation to make lateral p-i-n diodes for current injection regions, while an electron beam (E-beam) lithography process uses nickel chrome (NiCr) heaters as tuning elements. The fabricated devices are characterized using swept optical vector network analyzer (OVNA) coherent measurements.
fully_reconfigurable_silicon_photonic_lattice_filters_with_four_cascaded_unit_cells.pdf
Levy, Jacob S., Mark A. Foster, Alexander L. Gaeta, and Michal Lipson. “Harmonic generation in silicon nitride ring resonators.” Optics Express 19, no. 12 (2011): 11415-11421. Abstract
We demonstrate second-and third-harmonic generation in a centrosymmetric CMOS-compatible material using ring resonators and integrated optical waveguides. The chi((2)) response is induced by using the nanoscale structure of the waveguide to break the bulk symmetry of silicon nitride (Si3N4) with the silicon dioxide (SiO2) cladding. Using a high-Q ring resonator cavity to enhance the efficiency of the process, we detect the second-harmonic output in the visible wavelength range with milliwatt input powers at telecom wavelengths. We also observe third-harmonic generation from the intrinsic chi((3)) susceptibility of the silicon nitride. Phase matching of the harmonic processes occurs due to the near coincidence of indices of refraction of the fundamental mode at the pump frequency and the corresponding higher-order modes of the harmonic fields. (C) 2011 Optical Society of America
harmonic_generation_in_silicon_nitride_ring_resonators.pdf
Luo, Lian-Wee, Gustavo S. Wiederhecker, Jaime Cardenas, Carl Poitras, and Michal Lipson. “High quality factor etchless silicon photonic ring resonators.” Optics Express 19, no. 7 (2011): 6284-6289. Abstract
We demonstrate high quality factor etchless silicon photonic ring resonators fabricated by selective thermal oxidation of silicon without the silicon layer being exposed to any plasma etching throughout the fabrication process. We achieve a high intrinsic quality factor of 510,000 in 50 mu m-radius ring resonators, corresponding to a ring loss of 0.8 dB/cm. The device has a total chip insertion loss of 2.5 dB, achieved by designing etchless silicon inverse nanotapers at both the input and output of the chip. (C) 2011 Optical Society of America
high_quality_factor_etchless_silicon_photonic_ring_resonators.pdf
Gabrielli, Lucas H., and Michal Lipson. “Integrated Luneburg lens via ultra-strong index gradient on silicon.” Optics Express 19, no. 21 (2011): 20122-20127. Abstract
Gradient index structures are gaining increased importance with the constant development of Transformation Optics and metamaterials. Our ability to fabricate such devices, while limited, has already demonstrated the extensive capabilities of those designs, in the forms of invisibility devices, as well as illusion optics and super-lensing. In this paper we present a low loss, high index contrast lens that is integrated with conventional nanophotonic waveguides to provide improved tolerance in fiber-to-chip optical links for future communication networks. This demonstration represents a positive step in making the extraordinary capabilities of gradient index devices available for integrated optics. (C) 2011 Optical Society of America
integrated_luneburg_lens_via_ultra-strong_index_gradient_on_silicon.pdf
On-chip spectrophotometry for bioanalysis using microring resonators
Nitkowski, Arthur, Antje Baeumner, and Michal Lipson. “On-chip spectrophotometry for bioanalysis using microring resonators.” Biomedical Optics Express 2, no. 2 (2011): 271-277. Abstract
We measure optical absorption in color-producing enzymatic reactions for biochemical analysis with a microscale optofluidic device. Cavity-enhanced laser spectrophotometry is performed on analytes within a microfluidic channel at visible wavelengths with silicon nitride microring resonators of 100 mu m radius and quality factor of similar to 180,000. The resonator transmission spectrum is analyzed to determine optical absorption with a detection limit of 0.12 cm(-1). The device can be used to detect the activity of individual enzymes in a few minutes within a 100 fL sensing volume. The high sensitivity, small footprint, and low analyte consumption make absorption-based microring resonators attractive for lab-on-a-chip applications. (C) 2011 Optical Society of America
on-chip_spectrophotometry_for_bioanalysis_using_microring_resonators.pdf
Sherwood-Droz, Nicolas, and Michal Lipson. “Scalable 3D dense integration of photonics on bulk silicon.” Optics Express 19, no. 18 (2011): 17758-17765. Abstract
We experimentally show vertically stacked, multi-layer, low-temperature deposited photonics for integration on processed microelectronics. Waveguides, microrings, and crossings are fabricated out of 400 degrees C PECVD Si3N4 and SiO2 in a two layer configuration. Waveguide losses of similar to 1 dB/cm in the L-band are demonstrated using standard processing and without post-deposition annealing, along with vertically separated intersections showing -0.04 +/- 0.002 dB/cross. Finally 3D drop rings are shown with 25 GHz channels and 24 dB extinction ratio. (C) 2011 Optical Society of America
scalable_3d_dense_integration_of_photonics_on_bulk_silicon.pdf
Foster, Mark A., Jacob S. Levy, Onur Kuzucu, Kasturi Saha, Michal Lipson, and Alexander L. Gaeta. “Silicon-based monolithic optical frequency comb source.” Optics Express 19, no. 15 (2011): 14233-14239. Abstract
We demonstrate the generation of broad-bandwidth optical frequency combs from a CMOS-compatible integrated microresonator. We characterize the comb quality using a novel self-referencing method and verify that the comb line frequencies are equidistant over a bandwidth of 115 nm (14.5 THz), which is nearly an order of magnitude larger than previous measurements. (C) 2011 Optical Society of America
silicon-based_monolithic_optical_frequency_comb_source.pdf
Xu, Lin, Noam Ophir, Michael Menard, Ryan Kin Wah Lau, Amy C. Turner-Foster, Mark A. Foster, Michal Lipson, Alexander L. Gaeta, and Keren Bergman. “Simultaneous wavelength conversion of ASK and DPSK signals based on four-wave-mixing in dispersion engineered silicon waveguides.” Optics Express 19, no. 13 (2011): 12172-12179. Abstract
We experimentally demonstrate four-wave-mixing (FWM)-based continuous wavelength conversion of optical differential-phase-shift-keyed (DPSK) signals with large wavelength conversion ranges as well as simultaneous wavelength conversion of dual-wavelength channels with mixed modulation formats in 1.1-cm-long dispersion-engineered silicon waveguides. We first validate up to 100-nm wavelength conversion range for 10-Gb/s DPSK signals, showcasing the capability to perform phase-preserving operations at high bit rates in chip-scale devices over wide conversion ranges. We further validate the wavelength conversion of dual-wavelength channels modulated with 10-Gb/s packetized phase-shift-keyed (PSK) and amplitude-shift-keyed (ASK) signals; demonstrate simultaneous operation on multiple channels with mixed formats in chip-scale devices. For both configurations, we measure the spectral and temporal responses and evaluate the performances using bit-error-rate (BER) measurements. (C) 2011 Optical Society of America
simultaneous_wavelength_conversion_of_ask_and_dpsk_signals_based_on_four-wave-mixing_in_dispersion_engineered_silicon_waveguides.pdf
Preston, Kyle, Yoon Ho Daniel Lee, Mian Zhang, and Michal Lipson. “Waveguide-integrated telecom-wavelength photodiode in deposited silicon.” Optics Letters 36, no. 1 (2011): 52-54. Abstract
We demonstrate photodiodes in deposited polycrystalline silicon at 1550 nm wavelength with 0.15 A/W responsivity, 40 nA dark current, and gigahertz time response. Subband absorption is mediated by defects that are naturally present in the polycrystalline material structure. The material exhibits a moderate absorption coefficient of 6 dB/cm, which allows the same microring resonator device to act as both a demultiplexing filter and a photodetector. We discuss the use of deposited silicon-based complementary metal-oxide semiconductor materials for nanophotonic interconnects. (C) 2010 Optical Society of America
waveguide-integrated_telecom-wavelength_photodiode_in_deposited_silicon.pdf
Lau, Ryan K. W., Michael Menard, Yoshitomo Okawachi, Mark A. Foster, Amy C. Turner-Foster, Reza Salem, Michal Lipson, and Alexander L. Gaeta. “Continuous-wave mid-infrared frequency conversion in silicon nanowaveguides.” Optics Letter 36, no. 7 (2011): 1263-1265. Abstract
We report the first demonstration of cw wavelength conversion from the telecommunications band to the mid-IR (MIR) region via four-wave mixing in silicon nanowaveguides. We measure a parametric bandwidth of 748nm by converting a 1636nm signal to produce a 2384nm idler and show continuously tunable wavelength conversion from 1792 to 2116nm. This report indicates that the advantages of silicon photonics may be leveraged to create devices for a large range of MIR applications that require cw operation. (C) 2011 Optical Society of America
continuous-wave_mid-infrared_frequency_conversion_in_silicon_nanowaveguides.pdf

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