arXiv subjects

Michal Lipson

Publications and source records attributed to Michal Lipson.

At least 73 records · Page 4Linked to original sources

arXiv2016

Thermally Controlled Comb Generation and Soliton Modelocking in Microresonators

We report the first demonstration of thermally controlled soliton modelocked frequency comb generation in microresonators. By controlling the electric current through heaters integrated with silicon nitride microresonators, we demonstrate a systematic and repeatable pathway to single- and multi-soliton modelocked states without adjusting the pump laser wavelength. Such an approach could greatly simplify the generation of modelocked frequency combs and facilitate applications such as chip-based dual-comb spectroscopy.

physics.optics↗

arXiv2016

Quantum Interference between Transverse Spatial Waveguide Modes

Integrated quantum optics has drastically reduced the size of table-top optical experiments to the chip-scale, allowing for demonstrations of large-scale quantum information processing and quantum simulation. However, despite these advances, practical implementations of quantum photonic circuits remain limited because they consist of large networks of waveguide interferometers that path encode information which do not easily scale. Increasing the dimensionality of current quantum systems using higher degrees of freedom such as transverse spatial field distribution, polarization, time, and frequency to encode more information per carrier will enable scalability by simplifying quantum computational architectures, increasing security and noise tolerance in quantum communication channels, and simulating richer quantum phenomena. Here we demonstrate a scalable platform for photonic quantum information processing using waveguide quantum circuit building blocks based on the transverse spatial mode degree of freedom: mode multiplexers and mode beamsplitters. A multimode waveguide is inherently a densely packed system of spatial and polarization modes that can be coupled by perturbations to the waveguide. We design a multimode waveguide consisting of three spatial modes (per polarization) and a nanoscale grating beamsplitter to show tunable quantum interference between pairs of photons in different transverse spatial modes. We also cascade these structures and demonstrate NOON state interferometry within a multimode waveguide. These devices have potential to perform transformations on more modes and be integrated with existing architectures, providing a scalable path to higher-dimensional Hilbert spaces and entanglement.

quant-ph↗

arXiv2015

Synchronization and Phase Noise Reduction in Micromechanical Oscillators Arrays Coupled through Light

Synchronization of many coupled oscillators is widely found in nature and has the potential to revolutionize timing technologies. Here we demonstrate synchronization in arrays of silicon nitride micromechanical oscillators coupled purely through optical radiation field. We show that the phase noise of the synchronized oscillators can be improved by almost 10 dB below the phase noise limit for each individual oscillator. These results open a practical route towards synchronized oscillator networks.

cond-mat.mes-hall↗

arXiv2015

Dual-pumped degenerate Kerr oscillator in a silicon nitride microresonator

We demonstrate a degenerate parametric oscillator in a silicon-nitride microresonator. We use two frequency-detuned pump waves to perform parametric four-wave mixing and operate in the normal group-velocity dispersion regime to produce signal and idler fields that are frequency degenerate. Our theoretical modeling shows that this regime enables generation of bimodal phase states, analogous to the \c{hi}(2)-based degenerate OPO. Our system offers potential for realization of CMOS-chip-based coherent optical computing and an all-optical quantum random number generator.

physics.optics↗

arXiv2015

Near-field radiative heat transfer between nanostructures in the deep sub-wavelength regime

Radiative heat transfer between parallel objects separated by deep sub-wavelength distances and subject to large thermal gradients (>100 K) could enable breakthrough technologies for electricity generation and thermal transport control. However, thermal transport in this regime has never been achieved experimentally due to the difficulty of maintaining large thermal gradients over nm-scale distances while avoiding other heat transfer mechanism such as conduction. Previous experimental measurement between parallel planes were limited to distances greater than 500 nm (with a 20 K thermal gradient), which is much larger than the theoretically predicted distance (<100 nm) required for most applications. Here we show near-field radiative heat transfer between parallel nanostructures in the deep sub-wavelength regime using high precision micro electromechanical (MEMS) displacement control. We also exploit the high mechanical stability of structures under high tensile stress to minimize thermal buckling effects and maintain small separations at large thermal gradients. We achieve an enhancement of heat transfer of almost two orders of magnitude relative to the far-field limit, which corresponds to a 54 nm separation. We also achieve a high temperature gradient (260 K) between the cold and hot surfaces while maintaining a ~100 nm distance.

cond-mat.mes-hall↗

arXiv2015

Silicon-Nitride Platform for Narrowband Entangled Photon Generation

CMOS-compatible photonic chips are highly desirable for real-world quantum optics devices due to their scalability, robustness, and integration with electronics. Despite impressive advances using Silicon nanostructures, challenges remain in reducing their linear and nonlinear losses and in creating narrowband photons necessary for interfacing with quantum memories. Here we demonstrate the potential of the silicon nitride (Si3N4) platform by realizing an ultracompact, bright, entangled photon-pair source with selectable photon bandwidths down to 30 MHz, which is unprecedented for an integrated source. Leveraging Si3N4's moderate thermal expansion, simple temperature control of the chip enables precise wavelength stabilization and tunability without active control. Single-mode photon pairs at 1550 nm are generated at rates exceeding 107 s-1 with mW's of pump power and are used to produce time-bin entanglement. Moreover, Si3N4 allows for operation from the visible to the mid-IR, which make it highly promising for a wide range of integrated quantum photonics applications.

quant-ph↗

arXiv2015

Tunable Squeezing Using Coupled Ring Resonators on a Silicon Nitride Chip

We demonstrate continuous tuning of the squeezing level generated in a double-ring optical parametric oscillator by externally controlling the coupling condition using electrically controlled integrated microheaters. We accomplish this by utilizing the avoided crossing exhibited by a pair of coupled silicon nitride microring resonators. We directly detect a change in the squeezing level from 0.5 dB in the undercoupled regime to 2 dB in the overcoupled regime, which corresponds to a change in the generated on-chip squeezing factor from 0.9 dB to 3.9 dB. Such wide tunability in the squeezing level can be harnessed for on-chip quantum enhanced sensing protocols which require an optimal degree of squeezing.

quant-ph↗

arXiv2015

Tunable frequency combs based on dual microring resonators

In order to achieve efficient parametric frequency comb generation in microresonators, external control of coupling between the cavity and the bus waveguide is necessary. However, for passive monolithically integrated structures, the coupling gap is fixed and cannot be externally controlled, making tuning the coupling inherently challenging. We design a dual-cavity coupled microresonator structure in which tuning one ring resonance frequency induces a change in the overall cavity coupling condition. We demonstrate wide extinction tunability with high efficiency by engineering the ring coupling conditions. Additionally, we note a distinct dispersion tunability resulting from coupling two cavities of slightly different path lengths, and present a new method of modal dispersion engineering. Our fabricated devices consist of two coupled high quality factor silicon nitride microresonators, where the extinction ratio of the resonances can be controlled using integrated microheaters. Using this extinction tunability, we optimize comb generation efficiency as well as provide tunability for avoiding higher-order mode-crossings, known for degrading comb generation. The device is able to provide a 110-fold improvement in the comb generation efficiency. Finally, we demonstrate open eye diagrams using low-noise phase-locked comb lines as a wavelength-division multiplexing channel.

physics.optics↗

arXiv2015

All-optical signal processing platforms for CMOS compatible integrated nonlinear optics

Nonlinear photonic chips have enabled the generation and processing of signals using only light, with performance far superior to that possible electronically - particularly with respect to speed. Although silicon-on-insulator has been the leading platform for nonlinear optics, its high two-photon absorption at telecommunications wavelengths poses a fundamental limitation. We review recent progress in non-silicon CMOS-compatible platforms for nonlinear optics, with a focus on Si3N4 and Hydex. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement. This review highlights their potential impact as well as the challenges to achieving practical solutions for many key applications.

physics.optics↗

arXiv2015

On-Chip Optical Squeezing

We present the first demonstration of all-optical squeezing in an on-chip monolithically integrated CMOS-compatible platform. Our device consists of a low loss silicon nitride microring optical parametric oscillator (OPO) with a gigahertz cavity linewidth. We measure 1.7 dB (5 dB corrected for losses) of sub-shot noise quantum correlations between bright twin beams generated in the microring four-wave-mixing OPO pumped above threshold. This experiment demonstrates a compact, robust, and scalable platform for quantum optics and quantum information experiments on-chip.

physics.optics↗

arXiv2015

Integrated switch for simultaneous mode-division multiplexing (MDM) and wavelength-division multiplexing (WDM)

Leveraging the spatial modes of multimode waveguides using mode-division multiplexing (MDM) on an integrated photonic chip allows unprecedented scaling of bandwidth density for on-chip communication. Switching channels between waveguides is critical for future scalable optical networks, but its implementation in multimode waveguides must address how to simultaneously control modes with vastly different optical properties. Here we present a platform for switching signals between multimode waveguides based on individually processing the spatial mode channels using single-mode elements. Using this wavelength-division multiplexing (WDM) compatible platform, we demonstrate a 1x2 multimode switch for a silicon chip which routes four data channels with low (<-20 dB) crosstalk. We show bit-error rates below 10^-9 and power penalties below 1.4 dB on all channels while routing 10 Gbps data when each channel is input and routed separately. The switch exhibits an additional power penalty of less than 2.4 dB when all four channels are simultaneously routed.

physics.optics↗

arXiv2014

Scalable integration of long-lived quantum memories into a photonic circuit

We demonstrate a photonic circuit with integrated long-lived quantum memories. Pre-selected quantum nodes - diamond micro-waveguides containing single, stable, and negatively charged nitrogen vacancy centers - are deterministically integrated into low-loss silicon nitride waveguides. Each quantum memory node efficiently couples into the single-mode waveguide (> 1 Mcps collected into the waveguide) and exhibits long spin coherence times of up to 120 μs. Our system facilitates the assembly of multiple quantum memories into a photonic integrated circuit with near unity yield, paving the way towards scalable quantum information processing.

physics.optics↗

arXiv2014

Waveguide-based single-shot temporal cross-correlator

We describe a novel technique for performing a single-shot optical cross-correlation in nanowaveguides. Our scheme is based on four-wave mixing between two orthogonally polarized input signals propagating with different velocities due to polarization mode dispersion. The cross-correlation is determined by measuring the spectrum of the idler wave generated by the four-wave mixing process.

physics.optics↗

arXiv2014

30 GHz Zeno-based Graphene Electro-optic Modulator

Graphene has generated exceptional interest as an optoelectronic material because its high carrier mobility and broadband absorption promise to make extremely fast and broadband electro-optic devices possible. Electro-optic graphene modulators reported to date, however, have been limited in bandwidth to a few GHz because of the large capacitance required to achieve reasonable voltage swings. Here we demonstrate a graphene electro-optic modulator based on the classical Zeno effect that shows drastically increased speed and efficiency. Our device operates with a 30 GHz bandwidth, over an order of magnitude faster than prior work, and a state-of-the-art modulation efficiency of 1.5 dB/V. We also show the first high-speed large-signal operation in a graphene modulator, paving the way for fast digital communications using this platform. The modulator uniquely uses silicon nitride waveguides, an otherwise completely passive material platform, with promising applications for ultra-low-loss broadband structures and nonlinear optics.

physics.optics↗

arXiv2014

Silicon-Chip Mid-Infrared Frequency Comb Generation

Optical frequency combs represent a revolutionary technology for high precision spectroscopy due to their narrow linewidths and precise frequency spacing. Generation of such combs in the mid-infrared (IR) spectral region (2-20 um) is of great interest due to the presence of a large number of gas absorption lines in this wavelength regime. Recently, frequency combs have been demonstrated in the MIR in several platforms, including fiber combs, mode-locked lasers, optical parametric oscillators, and quantum cascade lasers. However, these platforms are either relatively bulky or challenging to integrate on-chip. An alternative approach using parametric mixing in microresonators is highly promising since the platform is extremely compact and can operate with relatively low powers. However, material and dispersion engineering limitations have prevented the realization of a microresonator comb source past 2.55 um. Although silicon could in principle provide a CMOS compatible platform for on-chip comb generation deep into the mid-IR, to date, silicon's linear and nonlinear losses have prevented the realization of a microresonator-based comb source. Here we overcome these limitations and realize a broadband frequency comb spanning from 2.1 um to 3.5 um and demonstrate its viability as a spectroscopic sensing platform. Such a platform is compact and robust and offers the potential to be versatile and durable for use outside the laboratory environment for applications such as real-time monitoring of atmospheric gas conditions.

physics.optics↗

arXiv2014

Master-Slave Locking of Optomechanical Oscillators Over A Long Distance

Frequency-locking and other phenomena emerging from nonlinear interactions between mechanical oscillators are of scientific and technological importance. However, existing schemes to observe such behaviour are not scalable over distance. We demonstrate a scheme to couple two independent mechanical oscillators, separated in frequency by 80kHz and situated far from each other (3.2km), via light. Using light as the coupling medium enables this scheme to have low loss and be extended over long distances. This scheme is reversible and can be generalised for arbitrary network configurations.

physics.optics↗

arXiv2014

Eliminating Structural Loss in Optomechanical Resonators Using Elastic Wave Interference

Optomechanical resonators suffer from the dissipation of mechanical energy through the necessary anchors enabling the suspension of the structure. Here we show that such structural loss in an optomechnaical oscillator can be almost completely eliminated through the destructive interference of elastic waves using dual-disk resonators. We also present both analytical and numerical model that predicts the observed interference of elastic waves. Our experimental data reveal unstressed SiN devices with mechanical Q-factors up to $10^4$ at mechanical frequencies of $f=102$ MHz ($fQ = 10^{12}$) at room temperature.

physics.optics↗

arXiv2014

Strong polarization mode coupling in microresonators

We observe strong modal coupling between the TE00 and TM00 modes in Si3N4 ring resonators revealed by avoided crossings of the corresponding resonances. Such couplings result in significant shifts of the resonance frequencies over a wide range around the crossing points. This leads to an effective dispersion that is one order of magnitude larger than the intrinsic dispersion and creates broad windows of anomalous dispersion. We also observe the changes to frequency comb spectra generated in Si3N4 microresonators due polarization mode and higher-order mode crossings and suggest approaches to avoid these effects. Alternatively, such polarization mode-crossings can be used as a novel tool for dispersion engineering in microresonators.

physics.optics↗