Kenneth Jeffrey Orlowsky

Integrated four-channel Mach-Zehnder multi/demultiplexer fabricated with phosphorous doped SiO/sub 2/ waveguides on Si

An analysis and the device performance of an integrated optical 4-channel multi/demultiplexer based on Mach-Zehnder interferometers elements are presented. The channel spacing is 77 AA. Single-mode channel waveguides are made from P-doped SiO/sub 2/ core layers. Waveguide losses as low as 0.05 dB/cm and fiber-to-waveguide butt coupling as low as 0.5 dB for lambda =1.5 mu m have been obtained. The multiplexer transfers power from four input channels into a common output channel with an average fiber-to-fiber loss of 2.6 dB per channel. The average crosstalk of the demultiplexer is -16 dB. >

Efficient coupling of a semiconductor laser to an optical fiber by means of a tapered waveguide on silicon

A Si3N4 core waveguide, matched to a laser mode, is adiabatically tapered into a SiO2:P core waveguide, matched to a fiber mode. When used to couple the light from a semiconductor laser into an optical fiber, a loss of 3.1 dB is obtained, compared to a loss of 4.5 dB obtained with a lensed fiber.

Low loss Si(3)N(4)-SiO(2) optical waveguides on Si.

We have developed an optical integrated circuit waveguide technology based on conventional Si processing. We demonstrate waveguide losses of <0.3 dB/cm in the 1.3-1.6-microm wavelength range. We use a high refractive-index core of Si(3)N(4) surrounded by SiO(2) cladding layers, which provides a highly confined optical mode adequate for butt coupling to channel substrate buried heterostructure lasers. We report the first IR transmission experiments in these waveguides and find two absorption peaks associated with H in SiO(2) and Si(3)N(4) layers at 1.40 and 1.52 microm, respectively. The peak absorptions are 2.2 and 1.2 dB/cm, respectively, and these peaks can be largely removed by annealing at 1100-1200 degrees C.

Four-channel wavelength division multiplexers and bandpass filters based on elliptical Bragg reflectors

Four-channel multiplexers and four-wavelength bandpass filters based on elliptical Bragg reflectors (EBRs) are discussed. The channel spacing is 50 AA near 1.56 mu m. The EBRs are narrowband elliptical mirrors that can refocus light from an input waveguide to any one of a number of output waveguides. Spectrally, they perform similarly to Bragg reflectors. The devices were fabricated on silicon using silica-based waveguide technology. The elliptical gratings with 0.53- mu m periods were patterned using deep UV spatial frequency doubling photolithography. Multiplexers with single filtering and double filtering were demonstrated. With single filtering, the fiber-to-fiber insertion loss was 3.0+or-0.5 dB, and the crosstalk was -20 dB; with double filtering, the insertion loss was 4.0+or-0.5 dB, and the crosstalk was -30 dB. About 2 dB of this loss was due to coupling between the fibers and the waveguide. The additive loss associated with the EBR, including propagation, Bragg reflection, and coupling between input and output waveguides, was about 1 dB. >

Integrated optic adiabatic devices on silicon

A study of integrated optic devices based on adiabatic principles is reported. The components are a 3-dB coupler, a full coupler, a polarization splitter, a wavelength multiplexer, and two mode shape transformers. All components were fabricated from doped silica and silicon nitride films on silicon substrates. Results are given for an adiabatic full coupler and an adiabatic 3-dB coupler, an asymmetric Y-coupler for a 1.3-1.55- mu m-wavelength multiplexer, and a tapered waveguide for mode shape transformation. >

Refractive-index dispersion of phosphosilicate glass, thermal oxide, and silicon nitride films on silicon.

We present precise measurements of the refractive-index dispersion in the 0.6-1.5-microm range of dielectric films commonly used to form optical waveguides on Si. These are thermal SiO(2) and phosphosilicate glasses formed from several types of low pressure chemical vapor deposition and Si(3)N(4) formed by LPCVD. Mode refractive-index measurements were made with absolute accuracies of 1 x 10(-4). We show that for samples greater, similar3 microm thick, the error in the film refractive index, determined by extrapolation of the mode refractive index data of the lowest two modes, is less, similar1 x 10(-4). Annealing studies of the phosphosilicate glass samples show that films containing 2% or more of P reached their equilibrium refractive indices after annealing at 800 degrees C, while undoped silica films require annealing at 1100 degrees C to reach equilibrium.

Integrated optic adiabatic polarization splitter on silicon

An adiabatic polarization splitter, fabricated with silica and silicon nitride films on a silicon substrate, is demonstrated. A rejection of the unwanted polarization (cross talk) of −20 to −34 dB was achieved with single filtering and −35 to −45 dB with double filtering. The device had a 1.5 dB insertion loss and a very small wavelength dependence.

Performance characteristics of a 1.5 mu m single-frequency semiconductor laser with an external waveguide Braff reflector

Single-frequency operation of 1.5- mu m semiconductor lasers was obtained by combining a regular Fabry-Perot laser to an external waveguide Bragg reflector. The laser is characterized by very pure single-frequency operation, 10-MHz linewidth, and greatly-reduced frequency chirp under direct modulation. The laser has been tested in 1.7-Gb/s transmission experiments over 82.5 km of fiber. >

Compound Bragg reflection filters made by spatial frequency doubling lithography

A report is presented on the fabrication of complex Bragg filters with resonant wavelengths near 1.55 mu m, patterned by photolithography using a high-resolution deep ultraviolet stepper. The projection of gratings with quarter-micrometer features was made possible by the use of spatial frequency-doubling lithography. A single chip, processed entirely in the silicon facility, was used to demonstrate five Bragg reflectors of different wavelengths, a quarter-wave shifted resonator, broadband stacked filters with as many as 15 uniform Bragg reflector sections of different Bragg wavelengths, and broadband stacked filters containing a passband within the reflection band. The filters exhibited nearly ideal spectral behavior. >

Four-port integrated optic polarization splitter

A polarization splitter based on a Mach-Zehnder interferometer is demonstrated. The device was fabricated using dielectric films on silicon substrates.