Jagat Shakya

Bio: Jagat Shakya is an academic researcher from Cornell University. The author has contributed to research in topics: Silicon & Resonator. The author has an hindex of 17, co-authored 32 publications receiving 3512 citations. Previous affiliations of Jagat Shakya include Kansas State University.

12.5 Gbit/s carrier-injection-based silicon micro-ring silicon modulators

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.

Experimental realization of an on-chip all-optical analogue to electromagnetically induced transparency

Abstract: We provide the first experimental observation of structure tuning of the electromagnetically induced transparencylike spectrum in integrated on-chip optical resonator systems. The system consists of coupled silicon ring resonators with $10\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ diameter on silicon, where the coherent interference between the two coupled resonators is tuned. We measured a transparency-resonance mode with a quality factor of 11 800.

Cascaded silicon micro-ring modulators for WDM optical interconnection.

Abstract: We experimentally demonstrate cascaded silicon micro-ring modulators as the key components of a WDM interconnection system. We show clean eye-diagrams when each of the four micro-ring modulators is modulated at 4 Gbit/s. We show that optical inter-channel crosstalk is negligible with a channel spacing of 1.3 nm.

III-nitride blue microdisplays

Abstract: Prototype blue microdisplays have been fabricated from InGaN/GaN quantum wells. The device has a dimension of 0.5×0.5 mm2 and consists of 10×10 pixels 12 μm in diameter. Emission properties such as electroluminescence spectra, output power versus forward current (L–I) characteristic, viewing angle, and uniformity have been measured. Due to the unique properties of III-nitride wide-band-gap semiconductors, microdisplays fabricated from III nitrides can potentially provide unsurpassed performance, including high-brightness/resolution/contrast, high-temperature/high-power operation, high shock resistance, wide viewing angles, full-color spectrum capability, long life, high speed, and low-power consumption, thus providing an enhancement and benefit to the present capabilities of miniature display systems.

Experimental realization of an on-chip all-optical analogue to electromagnetically induced transparency

Abstract: We show experimentally an all-optical analogue to electromagnetically induced transparency due to coherent interference between two coupled resonators. We measured an EIT-like resonance mode with quality factor of 11,800 using silicon ring resonators.

Plasmonics beyond the diffraction limit

Abstract: Recent years have seen a rapid expansion of research into nanophotonics based on surface plasmon–polaritons. These electromagnetic waves propagate along metal–dielectric interfaces and can be guided by metallic nanostructures beyond the diffraction limit. This remarkable capability has unique prospects for the design of highly integrated photonic signal-processing systems, nanoresolution optical imaging techniques and sensors. This Review summarizes the basic principles and major achievements of plasmon guiding, and details the current state-of-the-art in subwavelength plasmonic waveguides, passive and active nanoplasmonic components for the generation, manipulation and detection of radiation, and configurations for the nanofocusing of light. Potential future developments and applications of nanophotonic devices and circuits are also discussed, such as in optical signals processing, nanoscale optical devices and near-field microscopy with nanoscale resolution.

Fano resonances in nanoscale structures

Abstract: Modern nanotechnology allows one to scale down various important devices (sensors, chips, fibers, etc.) and thus opens up new horizons for their applications. The efficiency of most of them is based on fundamental physical phenomena, such as transport of wave excitations and resonances. Short propagation distances make phase-coherent processes of waves important. Often the scattering of waves involves propagation along different paths and, as a consequence, results in interference phenomena, where constructive interference corresponds to resonant enhancement and destructive interference to resonant suppression of the transmission. Recently, a variety of experimental and theoretical work has revealed such patterns in different physical settings. The purpose of this review is to relate resonant scattering to Fano resonances, known from atomic physics. One of the main features of the Fano resonance is its asymmetric line profile. The asymmetry originates from a close coexistence of resonant transmission and resonant reflection and can be reduced to the interaction of a discrete (localized) state with a continuum of propagation modes. The basic concepts of Fano resonances are introduced, their geometrical and/or dynamical origin are explained, and theoretical and experimental studies of light propagation in photonic devices, charge transport through quantum dots, plasmon scattering in Josephson-junction networks, and matter-wave scattering in ultracold atom systems, among others are reviewed.

Silicon optical modulators

Abstract: Optical technology is poised to revolutionize short-reach interconnects. The leading candidate technology is silicon photonics, and the workhorse of such an interconnect is the optical modulator. Modulators have been improved dramatically in recent years, with a notable increase in bandwidth from the megahertz to the multigigahertz regime in just over half a decade. However, the demands of optical interconnects are significant, and many questions remain unanswered as to whether silicon can meet the required performance metrics. Minimizing metrics such as the device footprint and energy requirement per bit, while also maximizing bandwidth and modulation depth, is non-trivial. All of this must be achieved within an acceptable thermal tolerance and optical spectral width using CMOS-compatible fabrication processes. This Review discusses the techniques that have been (and will continue to be) used to implement silicon optical modulators, as well as providing an outlook for these devices and the candidate solutions of the future.

Silicon microring resonators

Abstract: An overview is presented of the current state-of-the-art in silicon nanophotonic ring resonators. Basic theory of ring resonators is discussed, and applied to the peculiarities of submicron silicon photonic wire waveguides: the small dimensions and tight bend radii, sensitivity to perturbations and the boundary conditions of the fabrication processes. Theory is compared to quantitative measurements. Finally, several of the more promising applications of silicon ring resonators are discussed: filters and optical delay lines, label-free biosensors, and active rings for efficient modulators and even light sources.

Device Requirements for Optical Interconnects to Silicon Chips

Abstract: We examine the current performance and future demands of interconnects to and on silicon chips. We compare electrical and optical interconnects and project the requirements for optoelectronic and optical devices if optics is to solve the major problems of interconnects for future high-performance silicon chips. Optics has potential benefits in interconnect density, energy, and timing. The necessity of low interconnect energy imposes low limits especially on the energy of the optical output devices, with a ~ 10 fJ/bit device energy target emerging. Some optical modulators and radical laser approaches may meet this requirement. Low (e.g., a few femtofarads or less) photodetector capacitance is important. Very compact wavelength splitters are essential for connecting the information to fibers. Dense waveguides are necessary on-chip or on boards for guided wave optical approaches, especially if very high clock rates or dense wavelength-division multiplexing (WDM) is to be avoided. Free-space optics potentially can handle the necessary bandwidths even without fast clocks or WDM. With such technology, however, optics may enable the continued scaling of interconnect capacity required by future chips.