A biosensor application of vertically coupled glass microring resonators with Q/spl sim/12 000 is introduced. Using balanced photodetection, very high signal to noise ratios, and thus high sensitivity to refractive index changes (limit of detection of 1.8/spl times/10/sup -5/ refractive index units), are achieved. Ellipsometry and X-ray photoelectron spectroscopy results indicate successful modification of biosensor surfaces. Experimental data obtained separately for a bulk change of refractive index of the medium and for avidin-biotin binding on the ring surface are reported. Excellent repeatability and close-to-complete surface regeneration after binding are experimentally demonstrated.

Optical sensing of biomolecules using microring resonators

We characterize an approach to make ultra-low-loss waveguides using stable and reproducible stoichiometric Si3N4 deposited with low-pressure chemical vapor deposition. Using a high-aspect-ratio core geometry, record low losses of 8-9 dB/m for a 0.5 mm bend radius down to 3 dB/m for a 2 mm bend radius are measured with ring resonator and optical frequency domain reflectometry techniques. From a waveguide loss model that agrees well with experimental results, we project that 0.1 dB/m total propagation loss is achievable at a 7 mm bend radius with this approach.

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Ultra-low-loss high-aspect-ratio Si3N4 waveguides.

A method of fabricating a semiconductor structure including the steps of providing a silicon substrate (10) having a surface (12), forming on the surface (12) of the silicon substrate (10), by atomic layer deposition (ALD), a seed layer (20;20') characterised by a silicate material and forming, by atomic layer deposition (ALD) one or more layers of a high dielectric constant oxide (40) on the seed layer (20;20').

Method for fabricating a semiconductor structure including a metal oxide interface with silicon

We demonstrate high confinement, low-loss silicon nitride ring resonators with intrinsic quality factor (Q) of 3∗106 operating in the telecommunication C-band. We measure the scattering and absorption losses to be below 0.065dB/cm and 0.055dB/cm, respectively.

High confinement micron-scale silicon nitride high Q ring resonator

Fabrication of monolithic lattice-mismatched semiconductor heterostructures with limited area regions having upper portions substantially exhausted of threading dislocations, as well as fabrication of semiconductor devices based on such lattice-mismatched heterostructures.

Lattice-Mismatched Semiconductor Structures with Reduced Dislocation Defect Densities and Related Methods for Device Fabrication

An opto-electronic integrated circuit (OEIC) apparatus is disclosed for generating an electrical signal at a frequency ≧10 GHz. The apparatus, formed on a single substrate, includes a semiconductor ring laser for generating a continuous train of mode-locked lasing pulses and a high-speed photodetector for detecting the train of lasing pulses and generating the electrical signal therefrom. Embodiments of the invention are disclosed with an active waveguide amplifier coupling the semiconductor ring laser and the high-speed photodetector. The invention has applications for use in OEICs and millimeter-wave monolithic integrated circuits (MMICs).

Apparatus for millimeter-wave signal generation

A monolithically integrated photonic circuit combining a semiconductor source of excitation light with an optically active waveguide formed on the substrate. The optically active waveguide is preferably formed of a spin-on glass to which are added optically active materials which can enable lasing action, optical amplification, optical loss, or frequency conversion in the waveguide, depending upon the added material.

Monolithically integrated solid state laser and waveguide using spin-on glass

An integrated optic gyroscope is disclosed which is based on a photonic integrated circuit (PIC) having a bidirectional laser source, a pair of optical waveguide phase modulators and a pair of waveguide photodetectors. The PIC can be connected to a passive ring resonator formed either as a coil of optical fiber or as a coiled optical waveguide. The lasing output from each end of the bidirectional laser source is phase modulated and directed around the passive ring resonator in two counterpropagating directions, with a portion of the lasing output then being detected to determine a rotation rate for the integrated optical gyroscope. The coiled optical waveguide can be formed on a silicon, glass or quartz substrate with a silicon nitride core and a silica cladding, while the PIC includes a plurality of III–V compound semiconductor layers including one or more quantum well layers which are disordered in the phase modulators and to form passive optical waveguides.

Integrated resonant micro-optical gyroscope and method of fabrication

Etching structures for state‐of‐the‐art electronic and optoelectronic devices such as heterojunction bipolar transistors, optical waveguide modulators, gratings, and vertical‐cavity surface‐emitting lasers often requires nonselective etching with depth accuracy on the order of ±8 nm. We disclose the application of in situ optical reflectance monitoring during chlorine reactive‐ion‐beam etching of III‐V compound heterostructure devices for real‐time determination of etch depth to ±8 nm independent of total etch depth. High‐vertical‐resolution etching of thick, layered structures is achieved through use of a resonant periodic set of reflective interfaces, greatly enhancing the reflected amplitude oscillations without detrimental effects on device performance. This method demonstrates that slight modifications of material structure to optimize monitor response greatly enhance the accuracy of nonselective dry etching.

Improved epitaxial layer design for real‐time monitoring of dry etching in III–V compound heterostructures with depth accuracy of ±8 nm

We present the first application of Cl2+H2 reactive‐ion‐beam etching of InP. Specularly smooth etching is achieved using an ion beam of 53%–73% Cl2 in H2 at a 300 eV extraction potential with the substrate held at 250 °C. InP etch morphology and rate are examined as functions of Cl2+H2 mixture, sample temperature, and chamber pressure. Significant deviation from the optimum smooth‐etch conditions are seen to result in rough surfaces.

G. Allen Vawter

Papers

Apparatus for millimeter-wave signal generation

Monolithically integrated solid state laser and waveguide using spin-on glass

Integrated resonant micro-optical gyroscope and method of fabrication

Improved epitaxial layer design for real‐time monitoring of dry etching in III–V compound heterostructures with depth accuracy of ±8 nm

Reactive‐ion‐beam etching of InP in a chlorine–hydrogen mixture