Abstract: In accordance with the invention, a high speed thermo-optic phase shifter comprises a length of optical waveguide including a waveguiding core of a first material having an index of refraction n1 and a first order temperature dependence |dn1/dT| and, optically coupled to the core, a length of a second material having an index n2 preferably greater than the core (n2>n1) and a first order temperature dependence |dn2/dT| than the core (|dn2/dT|>|dn1/dT|). Advantageously, the length of second material is adiabatically tapered at both ends. Upon heating, as by a resistance heater, the second material changes the optical pathlength by an amount predominantly determined by |dn2/dT| providing faster switching speed. In a preferred embodiment, the core comprises silica, and the second material comprises silicon to produce switching speeds up to a few hundred MHz.

Abstract: In accordance with the invention, a high speed thermo-optic phase shifter comprises a length of optical waveguide including a waveguiding core of a first material having an index of refraction n1 and a first order temperature dependence |dn1/dT| and, optically coupled to the core, a length of a second material having an index n2 preferably greater than the core (n2>n1) and a first order temperature dependence |dn2/dT| than the core (|dn2/dT|>|dn1/dT|). Advantageously, the length of second material is adiabatically tapered at both ends. Upon heating, as by a resistance heater, the second material changes the optical pathlength by an amount predominantly determined by |dn2/dT| providing faster switching speed. In a preferred embodiment, the core comprises silica, and the second material comprises silicon to produce switching speeds up to a few hundred MHz.

Abstract: The present invention includes a MZI comprising a pair of folded waveguides disposed between a pair of couplers. Each folded waveguide comprises a pair of segments intersecting at a reflector. The respective reflectors are different distances from the couplers to provide a major portion of the differential path length between the two arms. In a preferred embodiment, the reflectors are polysilicon mirrors and can be formed by etching through the intersecting waveguides and depositing polysilicon. The result is a compact MZI that can be used as a multiwavelength reference for a laser light source on a common silicon optical bench chip.

Abstract: The thermo-optically controlled optical couplers wherein the coupling region between the waveguides in the coupling section is filled with a material having a high dependence of refractive index on temperature thus making the thermo-optic control means more efficient and allowing a greater range of adjustment in the coupling coefficient for a given temperature change.

Abstract: In accordance with the invention, arrays optical sources are combined in a multilevel planar optical waveguide structure for insertion into an optical fiber laser. The basic element of the combiner is a planar array of multiple waveguides which converge and are gradually tapered to a single output waveguide. A plurality of such elements integrally formed on successive cladding layers provides a high power stack of vertically aligned outputs. An arrangement is described for using such apparatus in the amplification of optical communications signals.

Abstract: An optimized waveguide structure enables the functional integration of various passive optic components on a single substrate. The optimized waveguide structure is characterized by a thicker core layer than used for square core waveguides and a core width that changes according to different functional regions of the optic circuit within which it is incorporated. The height (H) of the waveguide core is determined by the thickness of the core layer defined during the fabrication process and is ideally uniform across the circuit. The width (W) of the core, however, is changed between functional regions by the photo-lithographic mask and the chemical etching during the fabrication process. By way of example, an optimized waveguide structure for a P-doped silica planar waveguide with a .DELTA. approximately 0.6% for wavelength .lambda.=1.2-1.7 .mu.m, has a single uniform height of H=6.7 .mu.m and a width that changes between W=4 .mu.m in a coupler region, W=5.5 .mu.m in a bend region, W=9 .mu.