Single-mode and single-polarization photonics with anchored-membrane waveguides

An integrated photonic platform with anchored-membrane structures, the T-Guide, is proposed and numerically investigated. These compact air-clad structures have high index contrast and are much more stable than prior membrane-type structures. Their semi-infinite geometry enables single-mode and single-polarization (SMSP) operation over unprecedented bandwidths. Modal simulations quantify this behavior, showing that an SMSP window of 2.75 octaves (1.2 - 8.1 {\mu}m) is feasible for silicon T-Guides, spanning almost the entire transparency range of silicon. Dispersion engineering for T-Guides yields broad regions of anomalous group velocity dispersion, rendering them a promising platform for nonlinear applications, such as wideband frequency conversion

Effects of the surrounding medium on the optical properties of a subwavelength aperture

Influence of the refractive index of the surrounding material on the performance of a C-shaped subwavelength aperture is investigated. The changes in the spectral response (0.6 mu m to 6 mu m wavelength range) and power throughput of the aperture in an optically opaque silver (Ag) film are described for two configurations: one where the film with the aperture is immersed in an infinite dielectric slab and the other where the metallic layer is immediately adjacent to a semi-infinite dielectric substrate. It is shown that, while the resonant wavelengths increase monotonically with refractive index for both cases, the rates of these increases, as well as the behavior of the power throughput, depend not only on the configuration, but also strongly on the transmission mode. These findings have important implications for the design of subwavelength aperture-enhanced devices

Electronically tunable silicon photonic delay lines

Electronically tunable optical true-time delay lines are proposed. The devices utilize the combination of apodised gratings and the free-carrier plasma effect to tune the enhanced delay of silicon waveguides at a fixed wavelength. Three variations of the proposed scheme are studied and compared. The compact and integrable devices can achieve tuning ranges as high as similar to 660 ps with a loss of \u3c 2.2 dB when operated in the reflection mode of the gratings. A delay of similar to 40 ps with a loss of \u3c 10 dB and an estimated operation bit rate of similar to 20 Gb/s can be achieved

Silicon-photonics-based wideband radar beamforming: basic design

Proposed is silicon-photonics-based phased array antenna beamforming for high-resolution long-range radars with wide instantaneous radio frequency (rf) bandwidth. Specifically, the proposed silicon-photonics beamformer platform offers the potential for cost-effective monolithic chip-scale integration of photonic delay lines, 2×2 optical switches, variable optical attenuators, and optical amplifiers that form the base unit of a rf transmit/receive array signal processor. In effect, the proposed silicon-photonics devices empower the design of a powerful proposed photonic beamformer with one time-delay unit per antenna element. Device-level designs studies are shown that promise meeting the high-resolution radar mission-critical requirements via time delays of up to 2.5 ns, switching times of less than 100 ns, optical isolations as good as 50 dB, and optical gains of up to 6 dB. Longer delays are achieved off chip using optical fibers

Silicon-on-nitride waveguides for mid- and near-infrared integrated photonics

Silicon-on-nitride ridge waveguides are demonstrated and characterized at mid-and near-infrared optical wavelengths. Silicon-on-nitride thin films were achieved by bonding a silicon handling die to a silicon-on-insulator die coated with a low-stress silicon nitride layer. Subsequent removal of the silicon-on-insulator substrate results in a thin film of silicon on a nitride bottom cladding, readily available for waveguide fabrication. At the mid-infrared wavelength of 3.39 mu m, the fabricated waveguides have a propagation loss of 5.2 +/- 0.6 dB/cm and 5.1 +/- 0.6 dB/cm for the transverse-electric and transverse-magnetic modes, respectively

Towards On-Chip Self-Referenced Frequency-Comb Sources Based on Semiconductor Mode-Locked Lasers.

Miniaturization of frequency-comb sources could open a host of potential applications in spectroscopy, biomedical monitoring, astronomy, microwave signal generation, and distribution of precise time or frequency across networks. This review article places emphasis on an architecture with a semiconductor mode-locked laser at the heart of the system and subsequent supercontinuum generation and carrier-envelope offset detection and stabilization in nonlinear integrated optics

Low-loss, submicron chalcogenide integrated photonics with chlorine plasma etching

A chlorine plasma etching-based method for the fabrication of high-performance chalcogenide-based integrated photonics on silicon substrates is presented. By optimizing the etching conditions, chlorine plasma is employed to produce extremely low-roughness etched sidewalls on waveguides with minimal penalty to propagation loss. Using this fabrication method, microring resonators with record-high intrinsic Q-factors as high as 450 000 and a corresponding propagation loss as low as 0.42 dB/cm are demonstrated in submicron chalcogenide waveguides. Furthermore, the developed chlorine plasma etching process is utilized to demonstrate fiber-to-waveguide grating couplers in chalcogenide photonics with high power coupling efficiency of 37% for transverse-electric polarized modes

Emerging heterogeneous integrated photonic platforms on silicon

Silicon photonics has been established as a mature and promising technology for optoelectronic integrated circuits, mostly based on the silicon-on-insulator (SOI) waveguide platform. However, not all optical functionalities can be satisfactorily achieved merely based on silicon, in general, and on the SOI platform, in particular. Long-known shortcomings of silicon-based integrated photonics are optical absorption (in the telecommunication wavelengths) and feasibility of electrically-injected lasers (at least at room temperature). More recently, high two-photon and free-carrier absorptions required at high optical intensities for third-order optical nonlinear effects, inherent lack of second-order optical nonlinearity, low extinction ratio of modulators based on the free-carrier plasma effect, and the loss of the buried oxide layer of the SOI waveguides at mid-infrared wavelengths have been recognized as other shortcomings. Accordingly, several novel waveguide platforms have been developing to address these shortcomings of the SOI platform. Most of these emerging platforms are based on heterogeneous integration of other material systems on silicon substrates, and in some cases silicon is integrated on other substrates. Germanium and its binary alloys with silicon, III–V compound semiconductors, silicon nitride, tantalum pentoxide and other high-index dielectric or glass materials, as well as lithium niobate are some of the materials heterogeneously integrated on silicon substrates. The materials are typically integrated by a variety of epitaxial growth, bonding, ion implantation and slicing, etch back, spin-on-glass or other techniques. These wide range of efforts are reviewed here holistically to stress that there is no pure silicon or even group IV photonics per se. Rather, the future of the field of integrated photonics appears to be one of heterogenization, where a variety of different materials and waveguide platforms will be used for different purposes with the common feature of integrating them on a single substrate, most notably silicon