Sensitivity to alcohols of a planar waveguide ring resonator fabricated by a sol-gel method

A planar waveguide ring resonator was fabricated by organic-inorganic hybrid sol-gel materials; its sensitivity to ethanol vapor was experimentally investigated. It was found that dips in the transmission spectrum of the device shifted to longer wavelengths with increasing the ethanol concentration, and its sensitivity showed a linear relation with the ethanol concentration, showing a coefficient of 1.13 pm/ppm. In addition, the transmission loss of the ring resonator decreased with increasing the ethanol concentration. The measured characteristics suggest that the device may be considered as one of the candidates of alcohol vapor sensors. (c) 2006 Elsevier B.V. All rights reserved.

后处理对离子交换磷酸盐玻璃平面光波导的影响

研究了退火和二次离子交换对Er^3＋／Yb^3＋共掺的磷酸盐玻璃平面光波导传输特性的影响。在退火过程中，由于热效应和波导层Ag^＋离子的浓度差使得Ag^＋离子重新分布；随着退火时间的延长和温度的升高，光波导模式数目逐渐增加，波导层深度加深，且波导表面折射率与玻璃基质折射率差减小，退火扩散深度与退火时间的平方根成正比。电子探针结果显示在二次离子交换后形成了掩埋式的光波导，Ag^＋离子浓度接近二次方分布，而掩埋式的光波导有助于降低光波导的传输损耗。

锥形光纤的结构与特性

Both transmission loss and coupling efficiency of tapered fibers are discussed in this paper.With the geometrical optics method,the fact is explained that transmission loss of tapered fiber is lower than that of cylindrical fiber.Simulation study finds that both tip radius of tapered fiber and cone angle of it have an effect on efficiency of tapered fibers.The effect of relative position between light source and tapered fiber on coupling efficiency of tapered fibers is also studied.

Sonar gain control in echolocating finless porpoises (Neophocaena phocaenoides) in an open water (L)

Source levels of echolocating free-ranging Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) were calculated using a range estimated by measuring the time delays of the signals via the surface and bottom reflection paths to the hydrophone, relative to the direct signal. Peak-to-peak source levels for finless porpoise were from 163.7 to 185.6 dB re:1 mu Pa. The source levels are highly range dependent and varied approximately as a function of the one-way transmission loss for signals traveling from the animals to the hydrophone. (c) 2006 Acoustical Society of America.

Compact four-channel reconfigurable optical add-drop multiplexer using silicon photonic wire

We designed and fabricated a four-channel reconfigurable optical add-drop multiplexer based on silicon photonic wire waveguide, which is controlled through the thermo-optic effect. The effective footprint of the device is about 1000 x 500 mu m(2). The minimum insertion loss including the transmission loss and coupling loss is about 10.7 dB. The tuning bandwidth is about 17 nm, the average tuning efficiency about 6.11 mW/nm and the tuning speed about 24.5 kHz. (c) 2009 Elsevier B.V. All rights reserved.

Research progresses of SOI optical waveguide devices and integrated optical switch matrix

SOI (silicon-on-insulator) is a new material with a lot of important performances such as large index difference, low transmission loss. Fabrication processes for SOI based optoelectronic devices are compatible with conventional IC processes. Having the potential of OEIC monolithic integration, SOI based optoelectronic devices have shown many good characteristics and become more and more attractive recently. In this paper, the recent progresses of SOI waveguide devices in our research group are presented. By highly effective numerical simulation, the single mode conditions for SOI rib waveguides with rectangular and trapezoidal cross-section were accurately investigated. Using both chemical anisotropic wet etching and plasma dry etching techniques, SOI single mode rib waveguide, MMI coupler, VOA (variable optical attenuator), 2X2 thermal-optical switch were successfully designed and fabricated. Based on these, 4X4 and 8X8 SOI optical waveguide integrated switch matrixes are demonstrated for the first time.

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.

Deep-etched high-density fused-silica transmission gratings with high efficiency at a wavelength of 1550 nm

We describe the design, fabrication, and excellent performance of an optimized deep-etched high-density fused-silica transmission grating for use in dense wavelength division multiplexing (DWDM) systems. The fabricated optimized transmission grating exhibits an efficiency of 87.1% at a wavelength of 1550 nm. Inductively coupled plasma-etching technology was used to fabricate the grating. The deep-etched high-density fused-silica transmission grating is suitable for use in a DWDM system because of its high efficiency, low polarization-dependent loss, parallel demultiplexing, and stable optical performance. The fabricated deep-etched high-density fused-silica transmission gratings should play an important role in DWDM systems. (c) 2006 Optical Society of America.

Precipitation of Ge nanoparticles from GeO2 glasses in transmission electron microscope

We show, using spatially resolved energy loss spectroscopy in a transmission electron microscopy (TEM), that GeO2 and GeO2-SiO2 glasses are extremely sensitive to high energy electrons. Ge nanoparticles can be precipitated in GeO2 glasses efficiently by the high-energy electron beam of a TEM. This is relevant to TEM characterization of luminescent Ge nanoparticles in silicate glasses, which may produce artificial results. (C) 2005 American Institute of Physics.

Mode Analysis and Design of a Low-Loss Photonic Crystal 60 degrees Waveguide Bend

The guided modes of a two-dimensional photonic crystal straight waveguide and a waveguide bend are studied in order to find the high transmission mechanism for the waveguide bend. We find that high transmission occurs when the mode patterns and wave numbers match, while the single-mode condition in the waveguide bend is not necessarily required. According to the mechanism, a simply modified bend structure with broad high transmission band is proposed. The bandwidth is significantly increased from 19 to 116 nm with transmission above 90%, and covers the entire C band of optical communication.

Nucleation of diamond by pure carbon ion bombardment - a transmission electron microscopy study

A cross-sectional high-resolution transmission electron microscopy (HRTEM) study of a film deposited by a 1 keV mass-selected carbon ion beam onto silicon held at 800 degrees C is presented. Initially, a graphitic film with its basal planes perpendicular to the substrate is evolving. The precipitation of nanodiamond crystallites in upper layers is confirmed by HRTEM, selected area electron diffraction, and electron energy loss spectroscopy. The nucleation of diamond on graphitic edges as predicted by Lambrecht [W. R. L. Lambrecht, C. H. Lee, B. Segall, J. C. Angus, Z. Li, and M. Sunkara, Nature, 364 607 (1993)] is experimentally confirmed. The results are discussed in terms of our recent subplantation-based diamond nucleation model. (c) 2005 American Institute of Physics.

Design, fabrication, and characterization of an ultracompact low-loss photonic crystal corner mirror

An ultracompact, low-loss, and broad-band corner mirror, based on photonic crystals, is investigated in this paper. Based on the theoretical analysis of the loss mechanism, the boundary layers of the photonic crystal region are revised to improve the extra losses, and the transmission characteristics are evaluated by using the 3-D finite-difference time-domain method. The device with optimized structure was fabricated on silicon-on-insulator substrate by using electron-beam lithography and inductively coupled plasma etching. The measured extra losses are about 1.1 +/- 0.4 dB per corner mirror for transverse-electronic polarization for the scanning wavelength range of 1510-1630 nm. Dimensions of the achieved PC corner mirror are less than ;7 x 7 mu m(2), which are only about one tenth of conventional wave-guide corner mirrors.

Optimization of mechanically induced long-period fibre grating transmission spectrum

A new double-layer grating template is designed to reduce the out-of-band loss as much as 1.8dB when the loss of LP03 reaches 10.2 dB. Meanwhile, we propose a method to remove the sidelobes in the transmission spectra by the adjustment of the thickness of pressure plates. The plate-thickness-induced shift of resonant wavelength and the attenuation of loss peak intensity when removing sidelobes can be modified by the fibre distance and contact point on the pressure plates.

Measurement of the optical transmission modes and losses of the poled guest-host polymer NAEC/PEK-c planar waveguides

The polyetherketone (PEK-c) guest-host polymer planar waveguides doped with (4'-nitro)-3-azo-9-ethyl-carbazole (NAEC) were prepared. The waveguide films were poled by corona-onset poling at elevated temperature (COPET), and the corona poling setup includes a grid voltage making the surface-charge distribution uniform. By using the prism-in coupling method, the dark-line spectrum given by the reflected intensity versus the angle of incidence have been obtained, and the optical transmission losses of mth modes have been measured for the poled polymer waveguides at lambda = 632.8 nm. The measurement result showed that the optical loss of the fundamental mode is less than 0.7 dB cm(-1) for the TE polarization. (C) 2000 Elsevier Science Ltd. All rights reserved.

TRANSMISSION ELECTRON-MICROSCOPY STUDY OF N+-IMPLANTED SILICON ON INSULATOR BY ENERGY-FILTERED IMAGING

We report on the first study of N+ -implanted silicon on insulator by energy-filtered imaging using an Opton electron microscope CEM 902 equipped Castaing-Henry electron optical system as a spectrometer. The inelastic images, energy window set at DELTA-E = 16 eV and DELTA-E = 25 eV according to plasmon energy loss of crystal Si and of silicon nitride respectively, give much structure information. The interface between the top silicon layer and the upper silicon nitride layer can be separated into two sublayers.