This study concerns the modelling, in a dynamic regime of nonlinear operation, of a silicon on insulator (SOI) monomode waveguide with a grating coupler used as a photodiode. This model is made in the dynamic regime and is based on variations of the refractive index caused by both the photo generation of an electron hole pair and by thermal effects that are due to the recombination of carriers and the Joule effect. This model allows one to determine the operating range of the photodetector by adjusting key parameters, such as: the incident power density, the angular detuning relative to the resonance and the bias voltage.

The paper reports the design, fabrication and characterization of silicon-on-insulator (SOI) microring resonators using shallow etched rib waveguides. The variation of the Q -factor of microring resonators as a function of the ring diameter and coupling gap between the input waveguide and the ring is studied. Such structures are fabricated using e-beam lithography and reactive ion etching steps. Propagation loss of shallow etching rib waveguide has been evaluated to 0.8 dB/cm for wavelengths around 1550 nm. With a ring diameter of 100 mum and a coupling gap of 450 nm, the measured Q -factor is 35300. These results are matched by 3-D numerical optical modeling.

The Emerald Ash Borer (EAB) was discovered on North American soil in the summer of 2002 near Detroit, Michigan, U.S., and has since spread to six states/provinces. To alleviate these costs, a method of sanitization is urgently needed. This study evaluated four different chemical sanitation methods in laboratory and field conditions. Treatments included two borate treatments, spray and dip, with concentrations ranging from 5% to 16.5% boric acid equivalents by mass and Preventol®, a technical grade imidacloprid treatment with solution concentrations ranging from 0.005% to 0.02% applied as sprays. When logs were reared indoors subsequent to treatment, the technical grade imidacloprid and the borate dip treatments reduced the infection levels significantly. For the outdoor-reared logs, only the technical grade imidacloprid had a significant effect. All chemical treatments did better under indoor rearing than they did under outdoor rearing. This has heavy implications for the development of a sanitization treatment to be used in actual applications. Observations of EAB adults after emergence indicate that borate treatments may negatively affect EAB adult health and survivability after emergence.

This paper reports on fabrication and characterization of two kinds of photodetectors: interdigited metal-germanium on silicon-metal photodetectors (Metal-Semiconductor-Metal or MSM) and pin germanium photodiodes for operation at optical telecommunication wavelengths. For both 1.31 mu m and 1.55 mu m wavelengths, the measured -3dB bandwidth of interdigited MSM photodetectors is 35 GHz under 2V bias for electrode spacing equal to 0.5 mu m. For pin diodes at 1.55 mu m wavelength, the measured -3dB bandwidth under -3V bias ranges from 9 to 29 GHz for mesa diameters from 20 to 7 mu m, respectively.

We report the experimental demonstration of a germanium metalsemiconductor-metal (MSM) photodetector integrated in a SOI rib waveguide. Femtosecond pulse and frequency experiments have been used to characterize such photodetectors. The measured bandwidth under 6V bias is about 25 GHz at 1.55 mu m wavelength with a responsivity as high as 1 A/W. The used technological processes are compatible with complementary-metal-oxide-semiconductor (CMOS) technology. (C) 2007 Optical Society of America.

SOI microwaveguides and associated devices (splitters, turns,...) are used for light distribution. Rib SOI geometries obtained by shallow etching of the silicon film offer definite advantages for the integration of active devices while fulfilling efficiency and compactness. Propagation losses of such waveguides are one order of magnitude smaller than for single mode strip waveguides. Rib-based compact and low loss optical signal distribution from one input to up to 1024 output points has been demonstrated. Light injection in submicron SOI waveguides is discussed. The indirect bandgap of silicon is not in favor of light emission and modulation. Realization of silicon sources and efficient high speed silicon-based modulators is a real challenge. For light detection, germanium can be grown on silicon and Ge photodetectors with -3dB bandwidths up to 30 GHz have been demonstrated.

An experimental characterization of the grating couplers for sub-micrometer silicon-on-insulator (SOI) waveguides is presented. The grating couplers have been designed, realized, and characterized for the +1 diffraction order at an operating wavelength of 1.31 mum for TE polarization. At the resonant angle, a coupling efficiency higher than 55% has been measured. The angular coupling range and the wavelength tolerance have been evaluated to 3deg and 20 nm, respectively. The grating coupler is followed by a taper, and about 50% of the input power at 1.31 mum is coupled into sub-micrometer rib and strip SOI waveguides. The ration between light power decoupled toward the cladding and light power decoupled toward the substrate is about three

Modulation-doped SiGe-Si multiple quantum well and all-silicon modulators embedded in reverse biased PIN junctions and integrated in SOI waveguides are described. Experimental evidence for electrorefractive effect is presented, and frequency operation is investigated

Different technologies for the fabrication of Germanium photodetectors were developed. Germanium was grown by RPCVD in a silicon cavity in order to provide a direct coupling with a rib silicon waveguide. With direct deposition of Ti/TiN/AlCu on Ge, Metal-Schotkky-Metal (MSM) diodes were formed. PIN photodiode were fabricated either with in-situ doping during RP- CVD epitaxy of Ge, either by ion implantation. For vertical PIN photodiode, the germanium was successfully etched either in mesa either anisotropically with Cl2 gazes. Small footprint Ge photodiodes can lead to high speed operation on CMOS

Electrorefractive effect is experimentally demonstrated in an all-silicon optical structure. A highly doped Si P+ layer is embedded in the intrinsic region of a PIN diode integrated in a SOI waveguide. Holes are confined at equilibrium around the P+ layer. By applying a reverse bias to the diode, electrical field sweeps the carriers out of the active region. Free carrier concentration variations are responsible for local refractive index variations leading to an effective index variation of the waveguide optical mode and to an optical absorption variation. As a figure of merit, the product VπLπ, determined from the measured effective index variation, is equal to 3.1Vcm. Furthermore, the device performances have theoretically been investigated. Estimations show that VπLπ as small as 1Vcm are feasible using optimized structures. Response times lower than 2ps are predicted, which gives the possibility to achieve very high-speed modulation. Furthermore, a temperature increases from 300 to 400K does not change the index variation amplitude, and despite the carrier mobility reduction, response times are still lower than 2ps.

The realization of integrated active devices is a key point; for on-chip optical interconnects at 1.3-1.5 mu m wavelengths. The required devices are high-speed, low-noise, and highly sensitive detectors, as well as efficient switching devices and optical modulators. In this context, as material compatibility must be insured, the group IV silicon-germanium technology is important due to the energy band engineering that it allows, with the integration of Si/SiGe heterostructures into the existing silicon technology. The aim of this chapter is to give a, review of the recent progress made in the field of active SiGe devices for optical interconnects. Attention is focused on strained-layer superlattice SiGe/Si and pure Ge photodetectors, as well on SiGe-based switching devices and optical modulators.

A structure based on the free-carrier-induced electrorefractive effect in Si/SiGe modulation-doped quantum wells, placed in the intrinsic region of a PIN diode has been proposed. Effective index variation produced by carrier depletion under a reverse bias leads to a phase modulation of a guided wave. The measured variation of the effective index is typically 2.10(-4) for a OV to 6V variation of the reverse bias voltage. This study is focused on the integration of modulation doped SiGe/Si quantum-well optical modulator in SOI submicron rib waveguides with optical losses lower than 0.4dB/cm. The influence of the geometrical parameters, of layer doping and of the metallic contacts has been determined through numerical simulations and optimized modulation structures are defined. The obtained factor of merit L pi V pi is then of 1.26 V.cm which can be favorably compared with the best published results obtained with other optimized modulators.

Experimental results for refractive index variation induced by depletion in a silicon structure integrated in a PIN diode are reported. Thermal effect has been dissociated from the electrical contribution due to carrier density variation induced by a reverse bias voltage. A figure of merit V(pi)L(pi) of 3.1 V.cm has been obtained at 1.55mum. Numerical simulations show a good agreement between experimental and theoretical index variations.

The low excess loss experimental demonstration of ten successive light divisions is presented. This distribution is realized by using shallow-etched rib silicon-on-insulator waveguides with compact beam splitters and 90° turns based on total internal reflection corner mirrors. The measured excess optical loss is only 0.7dB per division. This result is an important step in a 1 to 1024 optical distribution demonstration.

A SiGe/Si optical modulator based on the free-carrier plasma dispersion effect is presented. A SiGe/Si multilayer structure is included in a p-i-n diode and integrated in a submicrometric silicon-on-insulator (SOI) rib waveguide. A P+ Si layer inserted in the Si barriers provide holes that are confined in the SiGe wells at the equilibrium and can be depleted by applying a reverse bias. This structure offers high-speed phase modulation properties. Numerical simulations are used to design the optical modulator. An optimal structure is defined comprising three 10-nm-thick SiGe layers and four 5-nm-thick P+ Si layers. The predicted refractive index variation is 1.7 x 10(-4) under a -6-V bias voltage, and the associated absorption variation is 3 dB/cm. Intensity modulation is obtained by embedding the active region inside a microinterferometric structure. Using resonant cavities a few hundred micrometers long, a modulation depth larger than 60% is achieved with insertion losses of 12 dB, whereas Mach-Zehnder interferometers of a few millimeters length lead to modulation depths larger than 95% with insertion losses lower than 8 dB. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Experimental demonstration of successive optical divisions from one input to 1024 output points is presented using slightly etched submicron rib SOI waveguides. Excess loss per division of 0.7 dB has been measured.