# Yeshaiahu Fainman's research while affiliated with University of California, San Diego and other places

## Publications (547)

Preprint
Full-text available
Optical coherence tomography is state-of-the-art in non-invasive imaging of biological structures. Spectral Domain Optical Co-herence Tomography is the popularly used variation of this technique, but its performance is limited by the bandwidth and res-olution of the system. In this work, we theoretically formulate the use of phase modulators and de...
Preprint
Full-text available
Implementing optical-based memory and utilizing it for computation on the nanoscale remains an attractive but still a challenging task. While significant progress was achieved in nanophotonics, allowing to explore nonlinear optical effects and employ light-matter interaction to realize non-conventional memory and computation capabilities, light-liq...
Article
The design, fabrication, and characterization of a 16-element optical phased array (OPA) using a high index ( n = 3.1) silicon-rich silicon nitride (SRN) is demonstrated. We present one-dimensional beam steering with end-fire facet antennas over a wide steering range of >115° at a fixed wavelength of 1525 nm. A beam width of 6.3° has been measured...
Article
Full-text available
We theoretically and experimentally present a novel method to accurately extract coupling coefficients of directional couplers using a single circuit. It utilizes the phenomenon of resonance splitting induced by mode coupling in a ring resonator, where the splitting distance is directly proportional to the coupling coefficient of the coupler that c...
Article
There is little literature characterizing the temperature-dependent thermo-optic coefficient (TOC) for low pressure chemical vapor deposition (LPCVD) silicon nitride or plasma enhanced chemical vapor deposition (PECVD) silicon dioxide at temperatures above 300 K. In this study, we characterize these material TOC’s from approximately 300-460 K, yiel...
Article
We present a study of optical bi-stability in a 3.02 refractive index at 1550nm plasma enhanced chemical vapor deposition (PECVD) silicon-rich nitride (SRN) film, as it pertains to bi-stable switching, memory applications, and thermal sensing applications. In this work we utilize an SRN ring resonator device, which we first characterize at low-powe...
Preprint
Full-text available
The design, fabrication, and characterization of a 16-element optical phased array (OPA) using a high index (n = 3.1) silicon rich silicon nitride (SRN) is demonstrated. We present one-dimensional beam steering with end-fire facet antennas over a wide steering range of >115{\deg} at a fixed wavelength of 1525 nm. A spot size of 0.11{\deg} has been...
Article
In this paper, we experimentally demonstrate a broadband Archimedes spiral delay line with high packing density on a silicon photonic platform. This high density is achieved by optimizing the gap between the adjacent waveguides (down to sub-micron scale) in the spiral configuration. However, care must be taken to avoid evanescent coupling, the pres...
Article
The demand for ultra-long waveguides with tunable refractive index keeps growing in various applications, such as tunable delay line, Fourier transform spectrometers, microwave filters, signal processors, programmable photonics circuits, Lidar etc. Thermal tuning using integrated heaters is so far the most popular option to modulate the waveguide i...
Article
Full-text available
The proliferation of Internet-of-Things has promoted a wide variety of emerging applications that require compact, lightweight, and low-cost optical spectrometers. While substantial progresses have been made in the miniaturization of spectrometers, most of them are with a major focus on the technical side but tend to feature a lower technology read...
Article
3D imaging is essential for the study and analysis of a wide variety of structures in numerous applications. Coherent photonic systems such as optical coherence tomography (OCT) and light detection and ranging (LiDAR) are state-of-the-art approaches, and their current implementation can operate in regimes that range from under a few millimeters to...
Article
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Neurophotonics was launched in 2014 coinciding with the launch of the BRAIN Initiative focused on development of technologies for advancement of neuroscience. For the last seven years, Neurophotonics’ agenda has been well aligned with this focus on neurotechnologies featuring new optical methods and tools applicable to brain studies. While the BRAI...
Article
Bragg-grating based cavities and coupler designs present opportunities for flexible allocation of bandwidth and spectrum in silicon photonic devices. Integrated silicon photonic devices are moving toward mainstream, mass adoption, leading to the need for compact Bragg grating based designs. In this work we present a design and experimental validati...
Article
Full-text available
Surface-enhanced Raman spectroscopy employed in conjunction with post-processing machine learning methods is a promising technique for effective data analysis, allowing one to enhance the molecular and chemical composition analysis of information rich DNA molecules. In this work, we report on a room temperature inhomogeneous broadening as a functio...
Conference Paper
We observe from the bifurcation analysis that high spontaneous emission factor β contributes towards stable phase locking of two laterally coupled semiconductor lasers, with varying pump rate and non-zero frequency detuning being considered.
Conference Paper
Bridge-coupled metallo-dielectric nanolasers that can operate in the in-phase or out-of-phase modes are experimentally demonstrated. The lasing action is confirmed by conventional lasing characterizations, whereas the operating modes are identified by near-field and far-field imaging.
Article
We experimentally demonstrate bridge-coupled metallo-dielectric nanolasers that can operate in the in-phase or out-of-phase locking modes at room temperature. By varying the length of the bridge, we show that the coupling coefficients can be realized in support of the stable operation of any of these two modes. Both coupled nanolaser designs have b...
Preprint
Full-text available
Understanding light-matter interaction lays at the core of our ability to harness novel physical effects and to translate them into new capabilities realized in modern integrated photonics platforms. Here, we present the design and characterization of optofluidic components in integrated photonics platform, and numerically predict a series of novel...
Article
Phase-locked laser arrays have been extensively investigated in terms of their stability and nonlinear dynamics. Specifically, enhancing the phase-locking stability allows laser arrays to generate high-power and steerable coherent optical beams for a plethora of applications, including remote sensing and optical communications. Compared to other co...
Article
The design, fabrication, and characterization of low-loss ultra-compact bends in high-index (n=3.1 at λ=1550nm) plasma-enhanced chemical vapor deposition silicon-rich silicon nitride (SRN) were demonstrated and utilized to realize efficient, small footprint thermo-optic phase shifter. Compact bends were structured into a folded waveguide geometry t...
Article
We demonstrate the DC-Kerr effect in plasma enhanced chemical vapor deposition (PECVD) silicon-rich nitride (SRN) and use it to demonstrate a third order nonlinear susceptibility, χ(3), as high as (6±0.58)×10-19m2/V2. We employ spectral shift versus applied voltage measurements in a racetrack resonator as a tool to characterize the nonlinear suscep...
Preprint
Full-text available
We demonstrate the DC-Kerr effect in PECVD Silicon-rich Nitride (SRN) and use it to demonstrate a third order nonlinear susceptibility, \c{hi}^((3)), as high as (6 +/- 0.58)x10-19 m2/v2. We employ spectral shift versus applied voltage measurements in a racetrack ring resonator as a tool by which to characterize the nonlinear susceptibilities of the...
Preprint
Full-text available
Phase-locked laser arrays have been extensively investigated in terms of their stability and nonlinear dynamics. Specifically, enhancing the phase-locking stability allows laser arrays to generate high-power and steerable coherent optical beams for a plethora of applications, including remote sensing and optical communications. Compared to other co...
Preprint
Full-text available
The design, fabrication, and characterization of low loss ultra-compact bends in high index (n = 3.1 at {\lambda} = 1550 nm) PECVD silicon rich silicon nitride (SRN) is demonstrated and utilized to realize efficient, small footprint thermo-optic phase shifter. Compact bends are structured into a folded waveguide geometry to form a rectangular spira...
Article
Full-text available
The quantum Hall effect involves electrons confined to a two-dimensional plane subject to a perpendicular magnetic field, but it also has a photonic analogue1–6. Using heterostructures based on structured semiconductors on a magnetic substrate, we introduce compact and integrated coherent light sources of large orbital angular momenta7 based on the...
Article
Full-text available
We present an ultra-compact single-shot spectrometer on silicon platform for sparse spectrum reconstruction. It consists of 32 stratified waveguide filters (SWFs) with diverse transmission spectra for sampling the unknown spectrum of the input signal and a specially designed ultra-compact structure for splitting the incident signal into those 32 fi...
Article
We introduce and experimentally demonstrate a miniaturized integrated spectrometer operating over a broad bandwidth in the short-wavelength infrared (SWIR) spectrum that combines an add-drop ring resonator narrow band filter with a distributed Bragg reflector (DBR) based broadband filter realized in a silicon photonic platform. The contra-direction...
Article
An ultra‐high resolution Fourier transform spectrometer (FTS) realized in silicon photonic platform that can operate with broad band, narrow band as well as a combination of broad band and narrow band signals is reported. The ultra‐high resolution of the spectrometer is achieved by exploiting multiple techniques: a Michelson interferometer (MI) str...
Preprint
Full-text available
Surface enhanced Raman scattering (SERS) process results in a tremendous increase of Raman scattering cross section of molecules adsorbed to plasmonic metals and influenced by numerous physico-chemical factors such as geometry and optical properties of the metal surface, orientation of chemisorbed molecules and chemical environment. While SERS hold...
Article
Full-text available
Surface-enhanced Raman scattering (SERS) process results in a tremendous increase of Raman scattering cross section of molecules adsorbed to plasmonic metals and influenced by numerous physico-chemical factors such as geometry and optical properties of the metal surface, orientation of chemisorbed molecules and chemical environment. While SERS hold...
Conference Paper
We demonstrate a silicon single-shot spectrometer with 0.008mm ² footprint, the smallest on CMOS compatible platforms. Experimental results confirm a bandwidth of 180nm with a resolution of 0.45nm. It opens new pathway towards commercial integrated spectrometers.
Conference Paper
We demonstrate low loss ultra-compact bends in PECVD silicon rich silicon nitride and utilize them towards realizing efficient thermo-optic MMI switches with P π = 23 mW and a footprint of 68 x 68 µm ² .
Conference Paper
We demonstrate electro-optic switching using the DC-Kerr effects in a bus-coupled integrated photonic racetrack ring resonator made of Silicon-rich Nitride and find its third order nonlinear susceptibility, χ(3), of 6x10-19 m2/v2.
Article
Full-text available
The past two decades have seen widespread efforts being directed toward the development of nanoscale lasers. A plethora of studies on single such emitters have helped demonstrate their advantageous characteristics such as ultrasmall footprints, low power consumption, and room-temperature operation. Leveraging knowledge about single nanolasers, the...
Article
To realize ubiquitously used photonic integrated circuits, on-chip nanoscale sources are essential components. Subwavelength nanolasers, especially those based on a metal-clad design, already possess many desirable attributes for an on-chip source such as low thresholds, room-temperature operation and ultra-small footprints accompanied by electroma...
Article
Surface-enhanced Raman spectroscopy (SERS) is an attractive method for bio-chemical sensing due to its potential for single molecule sensitivity and the prospect of DNA composition analysis. In this manuscript we leverage metal specific chemical enhancement effect to detect differences in SERS spectra of 200-base length single-stranded DNA (ssDNA)...
Article
We demonstrate the thermo-optic properties of silicon-rich silicon nitride (SRN) films deposited using plasma-enhanced chemical vapor deposition (PECVD). Shifts in the spectral response of Mach-Zehnder interferometers (MZIs) as a function of temperature were used to characterize the thermo-optic coefficients of silicon nitride films with varying si...
Article
We experimentally demonstrate a silicon photonic chip-scale 16-channel wavelength division multiplexer (WDM) operating in the O-band. The silicon photonic chip consists of a common-input bus waveguide integrated with a sequence of 16 spectral add-drop filters implemented by 4-port contra-directional Bragg couplers and resonant cladding modulated pe...
Article
Two coupled nanolasers exhibit a mode switching transition, theoretically described by mode beating limit cycle oscillations. Their decay rate is vanishingly small in the thermodynamic limit, i.e., when the spontaneous emission noise tends to zero. We provide experimental statistical evidence of mesoscopic limit cycles (∼103 intracavity photons). S...
Preprint
We demonstrate the thermo-optic properties of silicon-rich silicon nitride (SRN) films deposited using plasma-enhanced chemical vapor deposition (PECVD). Shifts in the spectral response of Mach-Zehnder Interferometers (MZIs) as a function of temperature were used to characterize the thermo-optic coefficients of silicon nitride films with varying si...
Article
We present an experimental demonstration of notch filters with arbitrary center wavelengths capable of tunable analog output power values varying between full extinction of 15 and 0 dB. Each filter is composed of highly modular apodized four-port Bragg add/drop filters to reduce the crosstalk between concatenated devices. The constructed photonic i...
Article
We demonstrate a laser tunable in intensity with gigahertz tuning speed based on a III/V reflective semiconductor optical amplifier (RSOA) coupled to a silicon photonic chip. The silicon chip contains a Bragg-based Fabry–Perot resonator to form a passive bandpass filter within its stopband to enable single-mode operation of the laser. We observe a...
Preprint
We present a single-shot spectrometer on silicon platform with broad operation bandwidth, ultra high resolution as well as the smallest footprint on silicon so far. It consists of 32 stratified waveguide filters (SWFs) with diverse transmission spectra for sampling the unknown spectrum of the input signal and a specially designed ultra-compact stru...
Article
Bragg gratings are one of the most important building blocks for photonics integrated circuits. They could generate stopbands in the transmission spectra with corresponding passbands in the reflection spectra by introducing periodic perturbations to the waveguide to support Bloch modes. The perturbation is typically realized in a form of corrugatio...
Conference Paper
We use non-degenerate two-photon excitation where the two excitation beams are displaced in space outside the focal volume to increase the signal-to-background ratio (SBR), overcoming the fundamental penetration depth limit of conventional two-photon microscopy.
Conference Paper
We demonstrate that the fundamental thermal fluctuations can induce significant linewidth broadening effect in metallo-dielectric nanolasers through numerical simulation. Broader linewidths are observed with the decrease of resonator dimensions and the increase of ambient temperatures.
Conference Paper
Dense photonic integration requires miniahrrization of materials, devices and subsystems, including passive components (e.g., engineered composite metamaterials, filters, etc.), active components (e.g., lasers, modulators and nonlinear wave mixers) and integrated circuits (Fourier transform spectrometer, programmable phase modulator of free space m...
Article
We report an advanced Fourier transform spectrometer (FTS) on silicon with significant improvement compared with our previous demonstration in [Nat. Commun.9, 665 (2018)2041-1723]. We retrieve a broadband spectrum (7 THz around 193 THz) with 0.11 THz or sub nm resolution, more than 3 times higher than previously demonstrated [Nat. Commun.9, 665 (20...
Preprint
Optical metamaterials and metasurfaces which emerged in the course of the last few decades have revolutionized our understanding of light and light-matter interaction. While solid materials are naturally employed as key building elements for construction of optical metamaterials mainly due to their structural stability, practically no attention was...
Preprint
Full-text available
Two coupled semiconductor nanolasers exhibit a mode switching transition, theoretically characterized by limit cycle $-$or mode-beating$-$ oscillations. Their decay rate is vanishingly small in the thermodynamic limit, i.e. when the spontaneous emission noise $\beta$-factor tends to zero. We provide experimental evidence of mesoscopic limit cycles...
Article
Full-text available
Non-degenerate two-photon excitation (ND-TPE) has been explored in two-photon excitation microscopy. However, a systematic study of the efficiency of ND-TPE to guide the selection of fluorophore excitation wavelengths is missing. We measured the relative non-degenerate two-photon absorption cross-section (ND-TPACS) of several commonly used fluoroph...
Conference Paper
In non-degenerate two-photon excitation (ND-TPE), electronic transition of fluorophores happens via absorption of two photons with different energies. This contrasts with conventional - or degenerate - two-photon excitation (D-TPE), where two photons with identical energies are absorbed. ND-TPE can improve performance of two-photon microscopy by ex...
Preprint
Exploring and controlling the physical factors that determine the topography of thin liquid dielectric films are of interest in manifold fields of research in physics, applied mathematics, and engineering and have been a key aspect of many technological advancements. Visualization of thin liquid dielectric film topography and local thickness measur...
Article
The capability of nanolasers to generate coherent light in small volume resonators has made them attractive to be implemented in future ultra-compact photonic integrated circuits. However, compared to conventional lasers, nanolasers are also known for their broader spectral linewidths, that are usually on the order of 1 nm. While it is well known t...
Article
We experimentally demonstrate the lasing action of a new nanolaser design with a tunnel junction. By using a heavily doped tunnel junction for hole injection, we can replace the p-type contact material of a conventional nanolaser diode with a low-resistance n-type contact layer. This leads to a significant reduction of the device resistance and low...
Article
Full-text available
Microwave photonics uses light to carry and process microwave signals over a photonic link. However, light can instead be used as a stimulus to microwave devices that directly control microwave signals. Such optically controlled amplitude and phase-shift switches are investigated for use in reconfigurable microwave systems, but they suffer from lar...
Article
Full-text available
A technique that induces and maps tiny topographical changes in thin liquid dielectric films could have applications in interfacial science and industry. Shimon Rubin, Brandon Hong and Yeshaiahu Fainman of the University of California, San Diego used a heating laser to induce thermocapillary flows in thin liquid dielectric films. These films are us...
Article
Full-text available
Space-variant control of optical wavefronts is important for many applications in photonics, such as the generation of structured light beams, and is achieved with spatial light modulators. Commercial devices, at present, are based on liquid-crystal and digital micromirror technologies and are typically limited to kilohertz switching speeds. To rea...
Preprint
Microwave photonics uses light to carry and process microwave signals over a photonic link. However, light can instead be used as a stimulus to microwave devices that directly control microwave signals. Such optically controlled amplitude and phase-shift switches are investigated for use in reconfigurable microwave systems, but they suffer from lar...
Article
Full-text available
In non-degenerate two-photon microscopy (ND-TPM), the required energy for fluorescence excitation occurs via absorption of two photons of different energies derived from two synchronized pulsed laser beams. ND-TPM is a promising imaging technology offering flexibility in the choice of the photon energy for each beam. However, a formalism to quantif...
Article
A measurement method that can be used to extract the relative intensity noise of a nanolaser is introduced and analyzed. The method is based on optical injection of emission from a nanolaser, serving as a master oscillator, transferring its intensity fluctuations to a low-noise semiconductor laser serving as a slave oscillator. Using the stochastic...
Article
Full-text available
We present experimental results on second-harmonic generation in non-stoichiometric, silicon-rich nitride films. The as-deposited film presents a second-order nonlinear coefficient, or χ ⁽²⁾ , as high as 8 pm/V. This value can be widely tuned using the electric field induced second harmonic effect, and a maximum value of 22.7 pm/V was achieved with...
Conference Paper
We experimentally observe and isolate chemical-enhancement effects in the Raman spectra of nucleotides on gold nanorod surfaces. We compare the enhanced spectra with similar enhancements observed on silver surfaces, and demonstrate their potential for DNA composition analysis.
Article
This theoretical modeling and simulation paper presents designs and projected performance of an on-chip digital Fourier transform spectrometer using a thermo-optical Michelson grating interferometer operating at ~1550-nm and 2000 nm for silicon-on-insulator and for germanium-on-silicon technological platforms, respectively. The Michelson interferom...
Preprint
We present experimental results on second-harmonic generation in non-stoichiometric, silicon-rich nitride (SRN) films. The as-deposited film presents a second-order nonlinear coefficient, or \c{hi}(2), as high as 8pm/V. This value can be widely tuned using the electric field induced second harmonic effect (EFISH), and a maximum value of 22.7pm/V wa...
Article
Full-text available
We design, fabricate and analyze a nanostructured plasmonic light emitting diode (LED) that simultaneously increases the modulation speed and radiative efficiency, compared to conventional LEDs and unpatterned plasmonic LEDs respectively. Our structure, optimized to ensure its integrability with electrical contacts, couples an InGaN/GaN blue LED wi...
Article
Full-text available
The high signal throughput of Fourier transform spectroscopy has proved a boon to overcoming the difficulties of otherwise overwhelming detector noise in chemical infrared spectroscopy and near-infrared Raman spectroscopy, and is desirable for in situ measurement. Here we introduce a stationary channel dispersed Fourier transform (CDFT) spectromete...
Article
The first generation of hyperbolic metamaterials, metasurfaces, and naturally hyperbolic materials (HMMs) utilized the static and passive properties of their constituent metallic and dielectric components to achieve intriguing macroscopic behavior, such as imaging and focusing of light below the diffraction limit and the broadband modification to t...
Article
We study the propagation of surface plasmon polaritons (SPPs) on a metal surface which hosts a thin film of a liquid dielectric. The Ohmic losses that are inherently present due to the coupling of SPPs to conductors’ electron plasma, induce temperature gradients and fluid deformation driven by the thermocapillary effect, which lead to a nonlinear a...
Article
Full-text available
The analysis of DNA has led to revolutionary advancements in the fields of medical diagnostics, genomics, prenatal screening, and forensic science, with the global DNA testing market expected to reach revenues of USD 10.04 billion per year by 2020. However, the current methods for DNA analysis remain dependent on the necessity for fluorophores or c...
Article
Ideal integrated light emitters for optical interconnects should be compact in size, high in modulation bandwidth, efficient in energy consumption and tunable in frequency. Nanolasers are excellent candidates for such an application. In this article, we review and offer further in-depth analyses in three key aspects of recent nanolaser research, in...