Chae, Sang Hoon
Bhatt, Gaurang R.
Tadayon, Mohammad Amin
Basov, D. N.
The optical properties of transition metal dichalcogenides (TMDs) are known to change dramatically with doping near their excitonic resonances. However, little is known about the effect of doping on the optical properties of TMDs at wavelengths far from these resonances, where the material is transparent and therefore could be leveraged in photonic circuits. We demonstrate the strong electrorefractive response of monolayer tungsten disulfide (WS2) at near-infrared wavelengths (deep in the transparency regime) by integrating it on silicon nitride photonic structures to enhance the light-matter interaction with the monolayer. We show that the doping-induced phase change relative to the change in absorption (| increment n/increment k|) is 125, which is significantly higher than the | increment n/increment k| observed in materials commonly employed for silicon photonic modulators, including Si and III-V on Si, while accompanied by negligible insertion loss.
In one embodiment an optoelectronic system can include a photonics interposer having a substrate and a functional interposer structure formed on the substrate, a plurality of through vias carrying electrical signals extending through the substrate and the functional interposer structure, and a plurality of wires carrying signals to different areas of the functional interposer structure. The system can further include one or more photonics device integrally formed in the functional interposer structure, and one or more prefabricated component attached to the functional interposer structure.
Barnard, Arthur W.
Wiederhecker, Gustavo S.
McEuen, Paul L.
The field of miniature mechanical oscillators is rapidly evolving, with emerging applications including signal processing, biological detection(1) and fundamental tests of quantum mechanics(2). As the dimensions of a mechanical oscillator shrink to the molecular scale, such as in a carbon nanotube resonator(3-7), their vibrations become increasingly coupled and strongly interacting(8,9) until even weak thermal fluctuations could make the oscillator nonlinear(10-13). The mechanics at this scale possesses rich dynamics, unexplored because an efficient way of detecting the motion in real time is lacking. Here we directly measure the thermal vibrations of a carbon nanotube in real time using a high-finesse micrometre-scale silicon nitride optical cavity as a sensitive photonic microscope. With the high displacement sensitivity of 700 fm Hz(-1/2) and the fine time resolution of this technique, we were able to discover a realm of dynamics undetected by previous time-averaged measurements and a room-temperature coherence that is nearly three orders of magnitude longer than previously reported. We find that the discrepancy in the coherence stems from long-time non-equilibrium dynamics, analogous to the Fermi-Pasta-Ulam-Tsingou recurrence seen in nonlinear systems(14). Our data unveil the emergence of a weakly chaotic mechanical breather(15), in which vibrational energy is recurrently shared among several resonance modes-dynamics that we are able to reproduce using a simple numerical model. These experiments open up the study of nonlinear mechanical systems in the Brownian limit (that is, when a system is driven solely by thermal fluctuations) and present an integrated, sensitive, high-bandwidth nanophotonic interface for carbon nanotube resonators.
Schlaus, Andrew P.
Spencer, Michael S.
Zhu, X. -Y.
Lead halide perovskites are emerging as an excellent material platform for optoelectronic processes. There have been extensive discussions on lasing, polariton formation, and nonlinear processes in this material system, but the underlying mechanism remains unknown. Here we probe lasing from CsPbBr3 perovskite nanowires with picosecond (ps) time resolution and show that lasing originates from stimulated emission of an electron-hole plasma. We observe an anomalous blue-shifting of the lasing gain profile with time up to 25 ps, and assign this as a signature for lasing involving plasmon emission. The time domain view provides an ultra-sensitive probe of many-body physics which was obscured in previous time-integrated measurements of lasing from lead halide perovskite nanowires.
Tadayon, Mohammad Amin
Martyniuk, Kelly Marie
McGowan, Josephine Cecelia
Roberts, Samantha Pamela
Denny, Christine Ann
Ultra-compact miniaturized optical components for microendoscopic tools and miniaturized microscopes are required for minimally invasive imaging. Current microendoscopic technologies used for deep tissue imaging procedures are limited to a large diameter and/or low resolution due to manufacturing restrictions. We demonstrate a platform for miniaturization of an optical imaging system for microendoscopic applications with a resolution of 1 mu m. We designed our probe using cascaded micro-lenses and waveguides (lensguide) to achieve a probe as small as 100 mu m x 100 mu m with a field of view of 60 mu m in diameter. We demonstrate wide-field microscopy based on our polymeric probe fabricated using photolithography and a two-photon polymerization process. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Gaeta, Alexander L.
Kippenberg, Tobias J.
Recent developments in chip-based nonlinear photonics offer the tantalizing prospect of realizing many applications that can use optical frequency comb devices that have form factors smaller than 1 cm(3) and that require less than 1 W of power. A key feature that enables such technology is the tight confinement of light due to the high refractive index contrast between the core and the cladding. This simultaneously produces high optical nonlinearities and allows for dispersion engineering to realize and phase match parametric nonlinear processes with laser-pointer powers across large spectral bandwidths. In this Review, we summarize the developments, applications and underlying physics of optical frequency comb generation in photonic-chip wave-guides via supercontinuum generation and in microresonators via Kerr-comb generation that enable comb technology from the near-ultraviolet to the mid-infrared regime.
Jang, Jae K.
Gaeta, Alexander L.
The phenomenon of synchronization occurs universally across the natural sciences and provides critical insight into the behaviour of coupled nonlinear dynamical systems. It also offers a powerful approach to robust frequency or temporal locking in diverse applications including communications, superconductors and photonics. Here, we report the experimental synchronization of two coupled soliton mode-locked chip-based frequency combs separated over distances of 20 m. We show that such a system obeys the universal Kuramoto model for synchronization and that the cavity solitons from the microresonators can be coherently combined, which overcomes the fundamental power limit of microresonator-based combs. This study could significantly expand the applications of microresonator combs, and with its capability for massive integration it offers a chip-based photonic platform for exploring complex nonlinear systems.
Kippenberg, Tobias J.
Gaeta, Alexander L.
Gorodetsky, Michael L.
The development of compact, chip-scale optical frequency comb sources (microcombs) based on parametric frequency conversion in microresonators has seen applications in terabit optical coherent communications, atomic clocks, ultrafast distance measurements, dual-comb spectroscopy, and the calibration of astophysical spectrometers and have enabled the creation of photonic-chip integrated frequency synthesizers. Underlying these recent advances has been the observation of temporal dissipative Kerr solitons in microresonators, which represent self-enforcing, stationary, and localized solutions of a damped, driven, and detuned nonlinear Schrddinger equation. which was first introduced to describe spatial self-organization phenomena. The generation of dissipative Kerr solitons provide a mechanism by which coherent optical combs with bandwidth exceeding one octave can be synthesized and have given rise to a host of phenomena, such as the Stokes soliton, soliton crystals, soliton switching, or dispersive waves. Soliton microcombs are compact, are compatible with wafer-scale processing, operate at low power, can operate with gigahertz to terahertz line spacing, and can enable the implementation of frequency combs in remote and mobile environments outside the laboratory environment, on Earth, airborne, or in outer space.
Gaeta, Alexander L.
We demonstrate the generation of counter-rotating cavity solitons in a silicon nitride microresonator using a fixed, single-frequency laser. We demonstrate a dual three-soliton state with a difference in the repetition rates of the soliton trains that can be tuned by varying the ratio of pump powers in the two directions. Such a system enables a highly compact, tunable dual comb source that can be used for applications such as spectroscopy and distance ranging. (c) 2018 Optical Society of America
Since the emergence of optical fiber communications, lithium niobate (LN) has been the material of choice for electro-optic modulators, featuring high data bandwidth and excellent signal fidelity. Conventional LN modulators however are bulky, expensive and power hungry, and cannot meet the growing demand in modern optical data links. Chip-scale, highly integrated, LN modulators could offer solutions to this problem, yet the fabrication of low-loss devices in LN thin films has been challenging. Here we overcome this hurdle and demonstrate monolithically integrated LN electro-optic modulators that are significantly smaller and more efficient than traditional bulk LN devices, while preserving LN's excellent material properties. Our compact LN electro-optic platform consists of low-loss nanoscale LN waveguides, micro-ring resonators and miniaturized Mach-Zehnder interferometers, fabricated by directly shaping LN thin films into sub-wavelength structures. The efficient confinement of both optical and microwave fields at the nanoscale dramatically improves the device performances featuring a half-wave electro-optic modulation efficiency of 1.8 V center dot cm while operating at data rates up to 40 Gbps. Our monolithic LN nanophotonic platform enables dense integration of high-performance active components, opening new avenues for future high-speed, low power and cost-effective communication networks. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Near-field thermophotovoltaics (NFTPV) is a promising approach for direct conversion of heat to electrical power. This technology relies on the drastic enhancement of radiative heat transfer (compared to conventional blackbody radiation) that occurs when objects at different temperatures are brought to deep subwavelength distances (typically <100 nm) from each other. Achieving such radiative heat transfer between a hot object and a photovoltaic (PV) cell could allow direct conversion of heat to electricity with a greater efficiency than using current solid-state technologies (e.g., thermoelectric generators). One of the main challenges in the development of this technology, however, is its incompatibility with conventional silicon PV cells. Thermal radiation is weak at frequencies larger than the similar to 1.1 eV bandgap of silicon, such that PV cells with lower excitation energies (typically 0.4-0.6 eV) are required for NFTPV. Using low bandgap III-V semiconductors to circumvent this limitation, as proposed in most theoretical works, is challenging and therefore has never been achieved experimentally. In this work, we show that hot carrier PV cells based on Schottky junctions between silicon and metallic films could provide an attractive solution for achieving high efficiency NFTPV electricity generation. Hot carrier science is currently an important field of research and several approaches are investigated for increasing the quantum efficiency (QE) of hot carrier generation beyond conventional Fowler model predictions. If the Fowler limit can indeed be overcome, we show that hot carrier-based NFTPV systems after optimization of their thermal radiation spectrum could allow electricity generation with up to 10-30% conversion efficiencies and 10-500 W/cm(2) generated power densities (at 900-1500 K temperatures). We also discuss how the unique properties of thermal radiation in the extreme near-field are especially well suited for investigating recently proposed approaches for high QE hot carrier junctions. We therefore expect our work to be of interest for the field of hot carrier science and by relying solely on conventional thin film materials to provide a path for the experimental demonstration of NFTPV energy conversion.
We demonstrate a new platform for minimally invasive, light delivery probes leveraging the maturing field of silicon photonics, enabling massively parallel fabrication of photonic structures. These Photonic Needles probes have sub-10 mu m cross-sectional dimensions, lengths greater than 3 mm-surpassing 1000 to 1 aspect ratio, and are released completely into air without a substrate below. We show the Photonic Needles to be mechanically robust when inserted into 2% agarose. The propagation loss of these waveguides is low-on the order of 4 dB/cm.
Gaeta, Alexander L
We demonstrate a novel approach to producing coherent, directional supercontinuum and cascaded dispersive waves using dispersion engineering in waveguides. By pumping in the normal group-velocity dispersion (GVD) regime, with two zero-GVD points to one side of the pump, pulse compression of the first dispersive wave generated in the anomalous GVD region results in the generation of a second dispersive wave beyond the second zero-GVD point in the normal GVD regime. As a result, we achieve an octave-spanning supercontinuum generated primarily to one side of the pump spectrum. We theoretically investigate the dynamics and show that the generated spectrum is highly coherent. We experimentally confirm this dynamical behavior and the coherence properties in silicon nitride waveguides by performing direct detection of the carrier-envelope-offset frequency of our femtosecond pump source using an f-2f interferometer. Our technique offers a path towards a stabilized, high-power, integrated supercontinuum source with low noise and high coherence, with applications including direct comb spectroscopy.=20