In a conventional slot waveguide structure, light is strongly confined in the slot region only either for the quasi-transverse electric (TE) (in a vertically oriented slot) or for the quasi-transverse magnetic (TM) (in a horizontally oriented slot) fundamental eigenmode, which enhances the optical forces, thus decreasing the optical power necessary to control the displacement of the device, but only for one eigenmode polarization at a time. In this work, we analyzed the optical forces in a cross-slot waveguide, which is formed by four suspended silicon waveguides separated by two orthogonal air slots. Cross-slot waveguides can strongly confine light in both quasi-TE and quasi-TM polarizations, thus enhancing the optical force and reducing the optical power for both. Our simulation results show that by adjusting the optical power and the light polarization, it is possible to control the displacement of the waveguides in the vertical or in the horizontal direction almost individually, or in both directions simultaneously. The proposed nano-optomechanical device has potential applications in active photonic devices and novel mechanisms for nanosensors and nanoactuators, such as optical nanogrippers and nanotweezers.
In a conventional slot waveguide structure, light is strongly confined in the slot region only either for the Quasi-TE (in a vertically oriented slot) or for the Quasi-TM (in a horizontally oriented slot) fundamental eigenmode, which enhances the optical forces, thus decreasing the optical power necessary to control the displacement of the device, but only for one eigenmode polarization at a time. In this work, we analyzed the optical forces in a cross-slot waveguide, which is formed by four suspended silicon waveguides separated by two orthogonal air slots. Cross-slot waveguides can strongly confine light in both Quasi-TE and Quasi-TM polarizations, thus enhancing the optical force and reducing the optical power for both. Our simulation results show that, by adjusting the optical power and the light polarization, it is possible to control the displacement of the waveguides in the vertical or in the horizontal direction almost individually, or in both directions simultaneously. The proposed NOMS device offers potential applications in active photonic devices, novel nanosensing and nanoactuators mechanisms, such as optical nanotweezers.
A fully polymer slot Young interferometer operating at 633 nm wavelength was fabricated by using nanoimprint molding method. The phase response of the interference pattern was measured with several concentrations of glucose-water solutions, utilizing both TE and TM polarization states. The sensor was experimentally found to detect a bulk refractive index change of 6.4×10-6 RIU. Temperature dependency of silicon slot waveguide has been demonstrated to be reduced with composite slot waveguide structure. The slot filled with thermally stable polymer having negative thermo-optic coefficient showed nearly an athermal operation of silicon slot waveguide. Experimental results show that the slot waveguide geometry covered with Ormocomp has thermo-optical coefficient of 6 pm/K.
This paper shows the first results we obtained for angular acceleration sensing using a fiber Bragg grating based angular accelerometer (FBGAA). We present measurements of angular accelerations imposed by an oscillating plate. Post processed moving average was used to reduce structural natural oscillation noises. Key structural mounting ideas are shown.
This paper presents the results of thermal tests performed with commercial optical fiber Bragg grating (FBG) temperature sensors and raw FBGs fabricated by Photonics Division of IEAv. Test results show significant differences on dynamic response behavior among all sensors and gratings under fast variations of environmental temperature. This effect may suggest a limitation on the use of sensors based on this technique in applications requiring fast and precise response.
Tunable silicon microring filters are used to demonstrate CMOS-compatible on-chip wavelength control of Er+ doped
fiber-lasers. The filter uses a 10 μm-diameter microring resonator based on single-mode silicon-on-insulator (SOI) strip
waveguides operating around the telecom range of 1.55 μm. A piece of Er+ doped fiber (EDF) serves as the gain media
which is pumped by a 980 nm laser diode. An on-chip Ni-Cr micro-heater consuming up to 38 mW is capable of tuning
the Si microring filter by 2.3 nm with a lasing linewidths narrower than 0.02 nm. This approach enables arbitrary
multiple wavelength generation on a silicon chip. Possible applications include on-chip and chip-to-chip densewavelength
division multiplexed communications, telecommunications and optical sensor interrogation.
We show high Raman gain in Silicon submicron-size strip waveguide. Using high confinement structures and pico-second pump pulses, we show 13.2-dB peak gain with 14.6-W peak pump power in a 7-mm long waveguide. The effect of free-carrier absorption is observed. We show a pico-second all-optical switch based on the Silicon waveguide, whose transmission is enhanced by the Raman gain.
Photonic crystals enable a reduction in the size of current photonic devices by virtue of forbidden propagation, except along engineered lines of defects. Furthermore, propagation above the band-gap has unique characteristics such as the superprism effect. Polymer materials which typically suffer from low optical confinement can benefit from photonic crystal structures to increase integration and functionality. Due to its unique advantages, several authors have reported attempts at fabricating photonic crystal structures in polymer materials. However, a clear photonic bandgap (PBG) was not demonstrated. In this paper we describe our recent work in design, simulation and fabrication polymer photonics devices. We will discuss specific slab photonic crystal devices based on 2D hexagonally packed structures achieved in polymethyl-methacrylate films. Supercomputer simulations were used to target optimal geometries that consist of points in a three dimensional space of lattice parameter, hole diameter and slab thickness that enable a design of the photonic bandgap of the structure. Fabrication of the devices was achieved through use of high-resolution electron-beam lithography and etching. A robust air-clad polymer photonic crystal film was enabled by the additional support of a 40 nm-thin low-stress silicon nitride layer.
Planar integrated photonic devices are typically designed for telecommunications wavelengths in the 1.55 micron range. For strong mode-confinement at these wavelengths, very high index contrasts are required and semiconductor materials are often used for the waveguide core. Recently, planar devices designed for the visible range were demonstrated with relatively large dimensions on the order of 0.5 - 5 mm. Here in contrast we demonstrate micron-size photonic devices with single-mode operation in the visible range. Devices made for light propagation in the visible range are designed for tapping specific wavelengths of light vertically out of the plane of integration. The structures are based on high confinement waveguides with an effective mode size on the order of 0.5 μm2.
We present experimental demonstration of fast all-optical switching in a one-dimensional photonic crystal nanocavity embedded in a Silicon waveguide. The transmission of the device is tuned by injecting free carriers into the nanocavity region using an optical pump beam. By strongly confining light in the photonic crystal nanocavity the sensitivity of light to small refractive index changes is enhanced. The small cavity volume (~0.1 μm3) and unpassivated sidewalls enable ultra-fast switching speeds with low pulse energies. Using a pulse energy of only 60pJ, a refractive index change of approximately 10-2 is obtained. This small index change, due to the high confinement nature of the cavity structure, leads to a strong change in transmission spectrum. Consequently, the resonance is shifted up to its full-width-at half-maximum (~7.5nm), and the transmission of the device is modulated by 71% with a time response of less than 1.5 ns. Such a device could open the door to the large-scale integration of ultra-fast modulators and switches.
This work presents a novel fiber optic rotation rate sensor based on the characteristics of an OEO with feedback loop tuned by Sagnac interferometer. Experimental results, which agree with theoretical predictions, show high sensitivity.