Showing papers by "Irfan Bulu published in 2013"

Integrated high-quality factor silicon-on-sapphire ring resonators for the mid-infrared

Abstract: We demonstrate high-quality (Q) factor grating-coupled ring resonators in a silicon-on-sapphire platform, operating at wavelengths between 4.3 and 4.6 μm. Total Q-factors of 151 000 and intrinsic Q-factors of 278 000 are measured, representing the highest Q-factors measured at the mid-infrared in Si.

Integrated High-Quality Factor Optical Resonators in Diamond

Abstract: The realization of an integrated diamond photonic platform, based on a thin single crystal diamond film on top of a silicon dioxide/silicon substrate, is reported. Using this approach, we demonstrate high-quality factor single crystal diamond race-track resonators, operating at near-infrared wavelengths (1550 nm). The devices are integrated with low-loss diamond waveguides terminated with polymer pads (spot size converters) to facilitate in- (out-) coupling of light from (to) an optical fiber. Optical characterization of these resonators reveal quality factors as high as ∼250 000 and overall insertion losses as low as 1 dB/facet. Scattering induced mode splitting as well as signatures of nonlinear effects such as optical bistability are observed at an input pump power of ∼100 mW in the waveguides.

Spontaneous emission and collection efficiency enhancement of single emitters in diamond via plasmonic cavities and gratings

Abstract: We demonstrate an approach, based on plasmonic apertures and gratings, to enhance the radiative decay rate of single nitrogen-vacancy (NV) centers in diamond while simultaneously improving their collection efficiency. Our structures are based on metallic resonators formed by surrounding sub-wavelength diamond nanoposts with a silver film, which can enhance the spontaneous emission rate of an embedded NV center. However, the collection efficiency of emitted photons remains low due to losses to surface plasmons and reflections at the diamond-air interface. In this work, we mitigate photon losses into these channels by incorporating grating structures into the plasmonic cavity system.

Spontaneous emission and collection efficiency enhancement of single emitters in diamond via plasmonic cavities and gratings

Abstract: We demonstrate an approach, based on plasmonic apertures and gratings, to enhance the radiative decay rate of single NV centers in diamond, while simultaneously improving their collection efficiency. Our structures are based on metallic resonators formed by surrounding sub-wavelength diamond nanoposts with a silver film, which can enhance the spontaneous emission rate of an embedded NV center. However, the collection efficiency of emitted photons remains low due to losses to surface plasmons and reflections at the diamond-air interface. In this work, we mitigate photon losses into these channels by incorporating grating structures into the plasmonic cavity system.

Integrated high-quality factor silicon-on-sapphire ring resonators for the mid-infrared

Abstract: We demonstrate high-quality (Q) factor grating-coupled silicon-on-sapphire ring resonators, operating around 4.5 μm. Total Q-factors of 151,000 and intrinsic Q-factors of 278,000 are measured, enabling applications in nonlinear wavelength generation and other areas.

Photonic Crystal Nanobeam Cavities for Tunable Filter and Router Applications

Abstract: We investigate the suitability of photonic crystal nanobeam cavities for interconnect applications. Owing to their small footprint, exactly the same as that of an optical waveguide, as well as ultrahigh quality factor resonances that they support, nanobeam cavities are attractive candidates for realization of densely integrated on-chip optical networks. We discus tunability of these filters using thermo-optic, electromechanic, and optomechanic effects, and we compare different reconfiguration strategies in terms of tuning hold power, tuning efficiency, and maximum operating frequency.

Optomechanical and photothermal interactions in suspended photonic crystal membranes

Abstract: We present here an optomechanical system fabricated with novel stress management techniques that allow us to suspend an ultrathin defect-free silicon photonic-crystal membrane above a Silicon-on-Insulator (SOI) substrate with a gap that is tunable to below 200 nm. Our devices are able to generate strong attractive and repulsive optical forces over a large surface area with simple in- and out- coupling and feature the strongest repulsive optomechanical coupling in any geometry to date (gOM/2π ≈ −65 GHz/nm). The interplay between the optomechanical and photo-thermal-mechanical dynamics is explored, and the latter is used to achieve cooling and amplification of the mechanical mode, demonstrating that our platform is well-suited for potential applications in low-power mass, force, and refractive-index sensing as well as optomechanical accelerometry.

Progress toward mid-IR chip-scale integrated-optic TDLAS gas sensors

Abstract: We are building prototype chip-scale low-power integrated-optic gas-phase chemical sensors based on mid-infrared (3-5μm) Tunable Diode Laser Absorption Spectroscopy (TDLAS). TDLAS is able to sense many gas phase chemicals with high sensitivity and selectivity. Novel gas sensing elements using low-loss resonant photonic crystal cavities or waveguides will permit compact integration of a laser source, sampling elements, and detector in configurations suitable for inexpensive mass production. Recently developed Interband Cascade Lasers (ICLs) that operate at room temperature with low power consumption are expected to serve as monochromatic sources to probe the mid-IR molecular spectral transitions. Practical challenges to fabricating these sensors include: a) selecting and designing the high-Q microresonator sensing element appropriate for the selected analyte; b) coupling laser light into and out of the sensing element; and c) device thermal management, especially stabilizing laser temperature with the precision needed for sensitive spectroscopic detection. This paper describes solutions to these challenges.

An on-chip diamond optical parametric oscillator

Abstract: Efficient, on-chip optical nonlinear processes are of great interest for the development of compact, robust, low-power consuming systems for applications in spectroscopy, metrology, sensing and classical and quantum optical information processing. Diamond holds promise for these applications, owing to its exceptional properties. However, although significant progress has been made in the development of an integrated diamond photonics platform, optical nonlinearities in diamond have not been explored much apart from Raman processes in bulk samples. Here, we demonstrate optical parametric oscillations (OPO) via four wave mixing (FWM) in single crystal diamond (SCD) optical networks on-chip consisting of waveguide-coupled microring resonators. Threshold powers as low as 20mW are enabled by ultra-high quality factor (1*10^6) diamond ring resonators operating at telecom wavelengths, and up to 20 new wavelengths are generated from a single-frequency pump laser. We also report the inferred nonlinear refractive index due to the third-order nonlinearity in diamond at telecom wavelengths.

An on-chip optical parametric oscillator in diamond

Abstract: We demonstrate optical parametric oscillation via four-wave mixing in waveguide-integrated, single crystal diamond micro-ring resonators. Threshold powers as low as 20 mW are enabled by high quality factor (~1 million) resonators operating at telecom wavelengths.