The present invention relates to telecommunication techniques and integrated circuit (IC) devices. More specifically, embodiments of the present invention provide an off-quadrature modulation system. Once an off-quadrature modulation position is determined, a ratio between DC power transfer amplitude and dither tone amplitude for a modulator is as a control loop target to stabilize off-quadrature modulation. DC power transfer amplitude is obtained by measuring and sampling the output of an optical modulator. Dither tone amplitude is obtained by measuring and sampling the modulator output and performing calculation using the optical modulator output values and corresponding dither tone values. There are other embodiments as well.

A semiconductor device includes a first insulating layer, an optical waveguide formed on the first insulating layer, a fixed charge layer formed on the first insulating layer such that the fixed charge layer covers the optical waveguide, and a second insulating layer formed on the fixed charge layer.

A silicon modulator where the doping profile varies along the lateral and/or longitudinal position in the transition zones to achieve improved performance in terms of optical attenuation or contact access resistance or both. A modulator includes a core; a first transition zone that is a P-side region adjacent to the waveguide core, the first transition zone has a first longitudinal doping profile; and a second transition zone that is an N-side region adjacent to the core on an opposite side as the first transition region, the second transition zone has a second longitudinal doping profile; the first longitudinal doping profile has a variation of doping concentration along a longitudinal direction in the first transition region to mimic a first lateral doping profile, and the second longitudinal doping profile has a variation of doping concentration along a longitudinal direction in the second transition region to mimic a second lateral doping profile.

A MOSCAP phase adjuster includes two conductive regions with a thin insulating region therebetween, where charge is accumulated or depleted. In conventional MOSCAP modulators, the conductive and insulating regions are superposed layers, extending horizontally parallel to the substrate, which limits waveguide design and mode confinement, resulting in reduced phase shift performance. An improved MOSCAP phase adjuster and method of fabricating a MOSCAP phase adjuster includes depositing the material for the second conductive region beside and over top of the first conductive region after oxidation, and selectively etching the material to form the second conductive region.

A monolithically integrated optical analog-to-digital conversion system based on a lithium niobate-silicon wafer, and a method for manufacturing the same, wherein a novel wafer (lithium niobate-silicon wafer) is used to implement the monolithically integrated optical analog-to-digital conversion system having multiple photonic devices, including an electro-optical modulator array, a tunable delay line array, an electronic circuit, and the like. As a result, multiple devices are manufactured on one chip, and the performance advantages and the stability of the system are guaranteed. Moreover, the present invention provides a CMOS-compatible method for manufacturing the system, so that the monolithically integrated optical analog-to-digital conversion system based on the lithium niobate-silicon wafer can be implemented on platforms of most chip manufacturers.

Structures for an electro-optic modulator and methods of fabricating a structure for an electro-optic modulator. The electro-optic modulator is arranged over a portion of a first waveguide core. The electro-optic modulator may include an electrode, an active layer, a second waveguide core, and a dielectric layer that is arranged between the active layer and the second waveguide core. The active layer is composed of a material having a refractive index that is a function of a bias voltage applied between the electrode and the first waveguide core.

Switches for electromagnetic radiation, including radiofrequency switches and optical switches, are provided. Also provided are methods of using the switches. The switches incorporate layers of high quality VO.sub.2 that are composed of a plurality of connected crystalline VO.sub.2 domains having the same crystal structure and orientation.

A MOSCAP phase adjuster includes two conductive regions with a thin insulating region therebetween, where charge is accumulated or depleted. In conventional MOSCAP modulators, the conductive and insulating regions are superposed layers, extending horizontally parallel to the substrate, which limits waveguide design and mode confinement, resulting in reduced phase shift performance. An improved MOSCAP phase adjuster and method of fabricating a MOSCAP phase adjuster includes depositing the material for the second conductive region beside and over top of the first conductive region after oxidation, and selectively etching the material to form the second conductive region.

A silicon modulator where the doping profile varies along the lateral and/or longitudinal position in the transition zones to achieve improved performance in terms of either optical attenuation or contact access resistance or both. A silicon-based modulator includes a waveguide core that is a PN junction region; a first transition zone that is a P-side region adjacent to the waveguide core and a first electrode; and a second transition zone that is an N-side region adjacent to the waveguide core on an opposite side as the first transition region and a second electrode; wherein a thickness of each of the first transition zone and the second transition zone is variable in any of a lateral direction, a longitudinal direction, and both the lateral direction and the longitudinal direction, each of the lateral direction and the longitudinal direction are relative to the waveguide core.

Various embodiments of a monolithic electro-optical (E-O) modulator are described herein. The monolithic E-O modulator may include a phase shifter having a suspended structure. The suspended structure may be realized by partially or completely removing silicon material underneath the active area of the phase shifter to form a void in the bulk silicon substrate supporting the phase shifter. The suspended structure may be utilized to result in a lower radio-frequency loss and an effective group refractive index of the phase shifter that is closer to the refractive index of silicon waveguides or optical fibers, both advantageous to enhancing the performance of the E-O modulator such as a higher operating bandwidth.