Publications

2008
Manipatruni, Sasikanth, Rajeev K. Dokania, Bradley Schmidt, Nicolas Sherwood-Droz, Carl B. Poitras, Alyssa B. Apsel, and Miclial Lipson. “Wide temperature range operation of micrometer-scale silicon electro-optic modulators.” Optics Letters 33 (2008): 2185-2187. Abstract
We demonstrate high bit rate electro-optic In modulation in a resonant micrometer-scale silicon modulator over an ambient temperature range of 15 K. We show that low bit error rates can be achieved by varying the bias current through the device to thermally counteract the ambient temperature changes. Robustness in the presence of thermal variations can enable a wide variety of applications for dense on chip electronic photonic integration. (C) 2008 Optical Society of America
2007
Dong, Po, Stefan F. Preble, and Michal Lipson. “All-optical compact silicon comb switch.” Optics Express 15 (2007): 9600-9605. Abstract
We demonstrate a 1x2 all-optical comb switch using a 200 mu m diameter silicon ring resonator with a switching time of less than 1 ns. The switch overcomes the small bandwidth of the traditional ring resonator, and works for wavelength division multiplexing applications. The device has a footprint of similar to 0.04 mm(2) and enables switching of a large number (similar to 40) of wavelength channels spaced by similar to 0.85 nm. (c) 2007 Optical Society of America.
Foster, Mark A., Amy C. Turner, Reza Salem, Michal Lipson, and Alexander L. Gaeta. “Broad-band continuous-wave parametric wavelength conversion in silicon nanowaveguides.” Optics Express 15 (2007): 12949-12958. Abstract
We demonstrate highly broad-band frequency conversion via four-wave mixing in silicon nanowaveguides. Through appropriate engineering of the waveguide dimensions, conversion bandwidths greater than 150 nm are achieved and peak conversion efficiencies of -9.6 dB are demonstrated. Furthermore, utilizing fourth-order dispersion, wavelength conversion across four telecommunication bands from 1477 nm (S-band) to 1672 nm (U-band) is demonstrated with an efficiency of -12 dB. (c) 2007 Optical Society of America.
Chen, Long, Nicolas Sherwood-Droz, and Michal Lipson. “Compact bandwidth-tunable microring resonators.” Optics Letters 32 (2007): 3361-3363. Abstract
Using interferometric couplers and thermal tuning, we demonstrate a novel design of compact microring resonators on silicon-on-insulator platform with tunable bandwidth from 0.1 to 0.7 nm. The structures present an extinction ratio higher than 23 dB and a footprint of less than 0.001 mm(2), which are suitable for integrated optical signal processing such as reconfigurable filtering and routing. (c) 2007 Optical Society of America.
Graydon, Oliver, and Michal Lipson. “A new colour for optical chips.” Nature Photonics 1 (2007): 298-298.
Xu, Qianfan, Sasikanth Manipatruni, Brad Schmidt, Jagat Shakya, and Michal Lipson. “12.5 Gbit/s carrier-injection-based silicon micro-ring silicon modulators.” Optics Express 15 (2007): 430-436. Abstract
We show a scheme for achieving high-speed operation for carrier-injection based silicon electro-optical modulator, which is optimized for small size and high modulation depth. The performance of the device is analyzed theoretically and a 12.5-Gbit/s modulation with high extinction ratio > 9dB is demonstrated experimentally using a silicon micro-ring modulator. (c) 2007 Optical Society of America.
Xu, Qianfan, and Michal Lipson. “All-optical logic based on silicon micro-ring resonators.” Optics Express 15 (2007): 924-929. Abstract
We demonstrate all-optical logic in a micron-size silicon ring resonator based on the free-carrier dispersion effect in silicon. We show AND and NAND operation at 310 Mbit/s with similar to 10-dB extinction ratio. The free-carrier-lifetime-limited bit-rate can be significantly improved by active carrier extraction. (c) 2007 Optical Society of America.
Salem, Reza, Mark A. Foster, Amy C. Turner, David F. Geraghty, Michal Lipson, and Alexander L. Gaeta. “All-optical regeneration on a silicon chip.” Optics Express 15 (2007): 7802-7809. Abstract
We demonstrate optical 2R regeneration in an integrated silicon device consisting of an 8-mm-long nanowaveguide followed by a ring-resonator bandpass filter. The regeneration process is based on nonlinear spectral broadening in the waveguide and subsequent spectral filtering through the ring resonator. We measure the nonlinear power transfer function for the device and find an operating peak power of 6 W. Measurements indicate that the output pulse width is determined only by the bandwidth of the bandpass filter. Numerical modeling of the nonlinear process including free-carrier effects shows that this device can be used for all-optical regeneration at telecommunication data rates. (c) 2007 Optical Society of America.
Xu, Qianfan, Po Dong, and Michal Lipson. “Breaking the delay-bandwidth limit in a photonic structure.” Nature Physics 3 (2007): 406-410. Abstract
Storing light on-chip, which requires that the speed of light be significantly slowed down, is crucial for enabling photonic circuits on-chip. Ultraslow propagation(1-3) and even stopping(4,5) of light have been demonstrated using the electromagnetically induced transparency effect in atomic systems(1,3-5) and the coherent population oscillation effect in solid-state systems(2). The wavelengths and bandwidths of light in such devices are tightly constrained by the property of the material absorption lines, which limits their application in information technologies. Various slow-light devices based on photonic structures have also been demonstrated(6-10); however, these devices suffer a fundamental trade-off between the transmission bandwidth and the optical delay. It has been shown theoretically(11-13) that stopping light on-chip and thereby breaking the fundamental link between the delay and the bandwidth can be achieved by ultrafast tuning of photonic structures. Using this mechanism, here we report the first demonstration of storing light using photonic structures on-chip, with storage times longer than the bandwidth-determined photon lifetime of the static device. The release time of the pulse is externally controlled.
Preble, Stefan F., Qianfan Xu, and Michal Lipson. “Changing the colour of light in a silicon resonator.” Nature Photonics 1 (2007): 293-296. Abstract
As the demand for high bandwidths in microelectronic systems increases, optical interconnect architectures are now being considered that involve schemes commonly used in telecommunications, such as wavelength-division multiplexing (WDM) and wavelength conversion(1). In such on-chip architectures, the ability to perform wavelength conversion is required. So far wavelength conversion on a silicon chip has only been demonstrated using schemes that are fundamentally all-optical(2-6), making their integration on a microelectronic chip challenging. In contrast, we show wavelength conversion obtained by inducing ultrafast electro-optic tuning of a microcavity. It is well known that tuning the parameters of an optical cavity induces filtering of different colours of light(7). Here we demonstrate that it can also change the colour of light. This is an effect often observed in other disciplines, for example, in acoustics, where the sound generated by a resonating guitar string can be modified by changing the length of the strings (that is, the resonators)(8). Here we show this same tuning effect in optics, enabling compact on-chip electrical wavelength conversion. We demonstrate a change in wavelength of up to 2.5 nm with up to 34% on-off conversion efficiency.
Lee, Benjamin G., Benjamin A. Small, Qianfan Xu, Michal Lipson, and Keren Bergman. “Characterization of a 4 x 4 Gb/s parallel electronic bus to WDM optical link silicon photonic translator.” Ieee Photonics Technology Letters 19 (2007): 456-458. Abstract
A 4 x 4 Gb/s microring modulator cascade, which can directly convert data from a parallel electrical bus to a multiple-wavelength optical signal in a single silicon-on-insulator waveguide, is demonstrated and characterized. The integrity of the modulated optical signal is verified using Q-factor extrapolations. In addition, the frequency characteristics and crosstalk, in terms of total harmonic distortion, are quantified. A transparent translator from electronics to optics such as this is crucial for the development of large-scale high-bandwidth interconnects based on photonic integrated circuits.
Schmidt, Bradley, Qianfan Xu, Jagat Shakya, Sasikanth Manipatruni, and Michal Lipson. “Compact electro-optic modulator on silicon-on-insulator substrates using cavities with ultra-small modal volumes.” Optics Express 15 (2007): 3140-3148. Abstract
We experimentally demonstrate a micron-size electro-optic modulator using a high-index-contrast silicon Fabry-Perot resonator cavity. This compact device consists of a 1-D cavity formed within a single mode silicon channel waveguide and an embedded p-i-n junction on a silicon-on-insulator platform. The entire device is 6.0 microns in length. We demonstrate modulation depths as large as 5.87 dB at speeds of 250 Mbps limited only by fabrication imperfections, with optimized theoretical speeds of several Gbps. (c) 2007 Optical Society of America.
Lipson, Michal. “An exercise in self control.” Nature Photonics 1 (2007): 18-19.
Sun, Rong, Po Dong, Ning-ning Feng, Ching-yin Hong, Jurgen Michel, Michal Lipson, and Lionel Kimerling. “Horizontal single and multiple slot waveguides: optical transmission at lambda=1550 nm.” Optics Express 15 (2007): 17967-17972. Abstract
We experimentally demonstrate the optical transmission at 1550 nm of the fundamental slot modes (quasi-TM modes) in horizontal single and multiple slot waveguides and ring resonators consisting of deposited amorphous silicon and silicon dioxide. We demonstrate that the horizontal multiple slot configuration provides enhanced optical confinement in low index slot regions compared to a horizontal single slot structure with the same total SiO2 layer thickness by comparing their thermo-optic coefficients for the horizontal slot ring resonators. We show in these early structures that horizontal slot waveguides have low propagation loss of 6 similar to 7 dB/cm. The waveguide loss is mainly due to a-Si material absorption. The addition of a Si/SiO2 interfaces does not introduce significant scattering loss in a horizontal multiple slot waveguide compared to a horizontal single slot waveguide. (c) 2007 Optical Society of America.
Small, Benjamin A., Benjamin G. Lee, Keren Bergman, Qianfan Xu, and Michal Lipson. “Multiple-wavelength integrated photonic networks based on microring resonator devices.” Journal of Optical Networking 6 (2007): 112-120. Abstract
Microring resonator devices implemented on silicon and silicon-on-insulator substrates have a unique potential to be used in high-bandwidth multiple-wavelength integrated photonic networks. A scheme for the wavelength allocation is proposed, and its feasibility is verified experimentally. The important system-level trade-offs that result from the proposed scheme, including those among bandwidth, device footprint, and electrical power consumption, are discussed as well. (c) 2007 Optical Society of America.
Schmidt, Bradley S., Allen H. J. Yang, David Erickson, and Michal Lipson. “Optofluidic trapping and transport on solid core waveguides within a microfluidic device.” Optics Express 15 (2007): 14322-14334. Abstract
In this work we demonstrate an integrated microfluidic/photonic architecture for performing dynamic optofluidic trapping and transport of particles in the evanescent field of solid core waveguides. Our architecture consists of SU-8 polymer waveguides combined with soft lithography defined poly(dimethylsiloxane) (PDMS) microfluidic channels. The forces exerted by the evanescent field result in both the attraction of particles to the waveguide surface and propulsion in the direction of optical propagation both perpendicular and opposite to the direction of pressure-driven flow. Velocities as high as 28 mu m/s were achieved for 3 mu m diameter polystyrene spheres with an estimated 53.5 mW of guided optical power at the trapping location. The particle-size dependence of the optical forces in such devices is also characterized. (C) 2007 Optical Society of America.
Manipatruni, Sasikanth, Qianfan Xu, and Michal Lipson. “PINIP based high-speed high-extinction ratio micron-size silicon electro-optic modulator.” Optics Express 15 (2007): 13035-13042. Abstract
We propose an electro-optic device in silicon based on a p-i-n-i-p device structure for charge transport. The proposed device exhibits carrier injection time of 10 ps and extraction time of 15 ps enabling 100 GHz operation. When integrated into a resonator the micron-size device operates at 40 Gbit/s with 12 dB extinction ratio and 2.25 fJ/bit/micron-length power dissipation. The proposed device is limited in speed only by the photon lifetime of the resonator. (c) 2007 Optical Society of America.
Preston, Kyle, Bradley Schmidt, and Michal Lipson. “Polysilicon photonic resonators for large-scale 3D integration of optical networks.” Optics Express 15 (2007): 17283-17290. Abstract
We demonstrate optical microresonators in polycrystalline silicon with quality factors of 20,000. We also demonstrate polycrystalline resonators vertically coupled to crystalline silicon waveguides. Electrically active photonic structures fabricated in deposited polysilicon layers would enable the large-scale integration of photonics with current CMOS microelectronics. (c) 2007 Optical Society of America.
2006
Okawachi, Y., M. A. Foster, J. E. Sharping, A. L. Gaeta, Q. F. Xu, and M. Lipson. “All-optical slow-light on a photonic chip.” Optics Express 14 (2006): 2317-2322. Abstract
We demonstrate optically tunable delays in a silicon-on-insulator planar waveguide based on slow light induced by stimulated Raman scattering (SRS). Inside an 8-mm-long nanoscale waveguide, we produce a group-index change of 0.15 and generate controllable delays as large as 4 ps for signal pulses as short as 3 ps. The scheme can be implemented at bandwidths exceeding 100 GHz for wavelengths spanning the entire low-loss fiber-optics communications window and thus represents an important step in the development of chip-scale photonics devices that process light with light. (c) 2006 Optical Society of America.
all-optical_slow-light_on_a_photonic_chip.pdf
Foster, M. A., A. C. Turner, J. E. Sharping, B. S. Schmidt, M. Lipson, and A. L. Gaeta. “Broad-band optical parametric gain on a silicon photonic chip.” Nature 441 (2006): 960-963. Abstract
Developing an optical amplifier on silicon is essential for the success of silicon-on-insulator (SOI) photonic integrated circuits. Recently, optical gain with a 1-nm bandwidth was demonstrated using the Raman effect(1-9), which led to the demonstration of a Raman oscillator(10,11), lossless optical modulation(12) and optically tunable slow light(13). A key strength of optical communications is the parallelism of information transfer and processing onto multiple wavelength channels. However, the relatively narrow Raman gain bandwidth only allows for amplification or generation of a single wavelength channel. If broad gain bandwidths were to be demonstrated on silicon, then an array of wavelength channels could be generated and processed, representing a critical advance for densely integrated photonic circuits. Here we demonstrate net on/off gain over a wavelength range of 28 nm through the optical process of phase-matched four-wave mixing in suitably designed SOI channel waveguides. We also demonstrate wavelength conversion in the range 1,511 - 1,591 nm with peak conversion efficiencies of +15.2 dB, which represents more than 20 times improvement on previous four-wave-mixing efficiencies in SOI waveguides(14-17). These advances allow for the implementation of dense wavelength division multiplexing in an all-silicon photonic integrated circuit. Additionally, all-optical delays(18), all-optical switches(19), optical signal regenerators(20) and optical sources for quantum information technology(21), all demonstrated using four-wave mixing in silica fibres, can now be transferred to the SOI platform.
nature04932.pdf

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