Longitudinal optic phonon-plasmon coupling in delta-doped metamorphic InAlAs/InGaAs high-electron-mobility transistor structures on GaAs substrates

InAlAs/InGaAs metamorphic high-electron-mobility transistor structures with different spacer layers on GaAs substrates are characterized by Raman measurements. The influence of In0.52Al0.48As spacer thickness on longitudinal optic phonon-plasmon coupling is investigated. It is found that the intensity of GaAs-like longitudinal optic phonon, which couples with collective intersubband transitions of two-dimensional electron gas, is strongly affected by the different subband energy spacings, subband electron concentrations, and wave function distributions, which are determined by different spacer thicknesses. (C) 2001 American Institute of Physics.

Electro-mass olfactory multi-sensor (EMMS)

For an olfactory sensor or electronic nose, the task is not only to detect the object concentration, but also to recognize it. It is well known that all the elements can be identified by their charge to mass ratio e(+)/m. We tried to imitate this principle for molecular recognition. Two kinds of sensors are used simultaneously in testing. One is quartz crystal microbalance (QCM) for detecting the change in mass, the other is interdigital electrode (IE) for detecting the change in conduction, as an electro-mass multi-sensor (EMMS). in this paper, the principle and the feasibility of this method are discussed. The preliminary results on the recognition of alcohol by EMMS coated with lipids are presented. Meanwhile, the multi-sensor can also be used as an instrument for research on some physico-chemistry problems. The change in conduction of coated membrane caused by one absorbed molecule is reported. It is found that when a QCM is coated with membrane, it still obeys the relationship Delta F (frequency change of QCM) = K Delta m (mass change of absorbed substance) and the proportional coefficient, K, depends not only on quartz properties but also on membrane characteristics as well. (C) 2000 Elsevier Science S.A. All rights reserved.

Electro-optical properties and temporal stability of the guest-host DCNP/PEK-c polymer thin film

The polyetherketone (PEK-c) guest-host system thin films in which the range of the weight percent of 3-(1,1-dicyanothenyl)-1-phenyl-4, 5- dihydro-1H-pryazole (DCNP) is from 20% to 50% were prepared. The predicted high value of electro-optical (EO) coefficient gamma(33) = 48.8 pm/V by using two-level model was obtained when the weight percent of DCNP in the polymer system is 40%, whereas EO coefficients are attenuated at higher chromophore loading then 40%. The temporal stability of the EO activity of the guest-host polymer was evaluated by probing the decay of the orientational order of the chromophores in the polymer system.

Superluminescent diode monolithically integrated with novel Y-branch by bundle integrated waveguide for fiber optic gyroscope - art. no. 68380D

We have developed a novel InP-based, ridge-waveguide photonic integrated circuit (PIC), which consists of a 1.1-um wavelength Y-branch optical waveguide with low loss and improved far field pattern and a 1.3-um wavelength strained InGaAsP-InP multiple quantum-well superluminescent diode, with bundle integrated guide (BIG) as the scheme for monolithic integration. The simulations of BIG and Y-branches show low losses and improved far-field patterns, based on the beam propagation method (BPM). The amplified spontaneous emission of the device is up to 10 mW at 120 mA with no threshold and saturation. Spectral characteristics of about 30 nm width and less than I dB modulation are achieved using the built-in anti-lasing ability of Y-branch. The beam divergence angles in horizontal and vertical directions are optimized to as small as 12 degrees x8 degrees, resulting in good fiber coupling. The compactness, simplicity in fabrication, good superluminescent performance, low transmission loss and estimated low coupling loss prove the BIG and Y-branch method to be a feasible way for integration and make the photonic integrated circuit of Y-branch and superluminescent diode an promising candidate for transmitter and transceiver used in fiber optic gyroscope.

Design considerations for a silicon-based p-i-n phase modulator in a double ridge waveguide with side isolating grooves

We present detail design considerations and simulation results of a forward biased carrier injection p-i-n modulator integrated on SOI rib waveguides. To minimize the free carrier absorption loss while keeping the comparatively small lateral dimensions of the modulator as required for high speed operation, we proposed two structural improvements, namely the double ridge (terrace ridge) structure and the isolating grooves at both sides of the double ridge. With improved carrier injection and optical confinement structure, the simulated modulator response time is in sub-ns range and absorption loss is minimized.

Investigation on pressure sensitivity of fiber optic mandrel hydrophone - art. no. 659544

Pressure sensitivity of the fiber optic mandrel hydrophone is analyzed in this paper. Based on the theory of elasticity, the mechanism of the pressure response is studied. The influence of the optical fiber on the compliant mandrel on the pressure response is taken into consideration for the first time. The radial deformation of the mandrel under the pressure of the fiber optic and the underwater pressure is analyzed in details. Based on the theory of photo-elasticity, the phase shift of the Mach-Zehnder interferometer is given. The pressure sensitivity is evaluated both theoretically and experimentally, and the results show a good correlation between the theoretical and experimental results.

Investigation on acceleration response of fiber optic mandrel hydrophone

The acceleration response of fiber optic mandrel hydrophone is studied based on the theory of elastic dynamics in this paper. For the first time the influence of the optical fiber on the acceleration response is taken into consideration. And the derivation of the radial deformation of the mandrel is presented in details. The acceleration response is evaluated both theoretically and experimentally and the results are in good agreement.

SOI-based thermo-optic waveguide switch matrix with spot size converters

A SOI-based thermo-optic waveguide switch matrix worked at 1.55 mu m, integrated with spot size converters is designed and fabricated for the first time. The insertion loss and polarization dependent loss are less than 13dB and 2dB, respectively. The extinction ratio is larger than 19dB. The response time is less than 5 mu s and the power consumption of the switch cell is about 200mW.

Recent progresses of SOI-based photonic devices - art. no. 60201R

SOI (Silicon on Insulator) based photonic devices, including stimulated emission from Si diode, RCE (Resonant Cavity Enhanced) photodiode with quantum structure, MOS (Metal Oxide Semiconductor) optical modulator with high frequency, SOI optical matrix switch and wavelength tunable filter are reviewed in the paper. The emphasis will be played on our recent results of SOI-based thermo-optic waveguide matrix switch with low insertion loss and fast response. A folding re-arrangeable non-blocking 4x4 matrix switch with total internal reflection (TIR) mirrors and a first blocking 16 x 16 matrix were fabricated on SOI wafer. The extinction ratio and the crosstalk are better. The insertion loss and the polarization dependent loss (PDL) at 1.55 mu m increase slightly with longer device length and more bend and intersecting waveguides. The insertion losses are expected to decrease 2-3 dB when anti-reflection films are added in the ends of the devices. The rise and fall times of the devices are 2.1 mu s and 2.3 mu s, respectively.

A low power consumption thermo-optic variable optical attenuator based on SOI material

A SOI thenno-optic variable optical attenuator with U-grooves based on a multimode interference coupler principle is fabricated. The dynamic attenuation range is 0 to 29 dB; at the wavelength range between 1510 nm and 1610nm, and the maximum power consumption is only l30mW. Compared to the variable optical attenuator without U-groove, the maximum power consumption decreases more than 230mW

Ultrahigh-resolution fiber-optic image guides derived from microstructured polymer optical fiber preforms

Ultrahigh-resolution fiber-optic image guides-fused image fiber, faceplate, and taper-were fabricated by using microstructured polymer optical fiber (MPOF) preforms composed of two polymers: polymethylmethacrylate and polystyrene. The pixel diameter in the resultant MPOF-based image guides was as small as 3 mu m. The imaging capabilities of these types of fiber-optic elements were demonstrated. (C) 2009 Optical Society of America

GAAS/GAALAS GRADED INDEX SEPARATE CONFINEMENT SINGLE QUANTUM-WELL SINGLE-MODE WAVE-GUIDE ELECTROABSORPTION LIGHT-MODULATOR

A GaAs/GaAlAs graded-index separate confinement single quantum well heterostructure single-mode ridge waveguide electroabsorption modulator was fabricated and investigated. For the modulator with a quantum well width of 100 angstrom and device length of 700-mu-m, an on/off ratio of 29.7 dB and estimated absorption insertion loss of 3 dB were obtained for TE polarised light with wavelength 8650 angstrom, and for TM polarisation the on/off ratio was 28.5 dB. With a switching voltage of 1 V, an on/off ratio of 15 dB was achieved. Photocurrent spectra exhibited a red shift of 600 angstrom of the absorption edge when the voltage applied to the PIN diode was varied from 0.5 to -7 V. The corresponding shift of the room temperature exciton peak energy was 96 meV.