An optical phase-shifting device includes a ribbed waveguide portion on an insulating layer, the waveguide portion having a p-n or p-i-n junction extending in a longitudinal direction and having a height. A pair of slab portions are disposed adjacent the waveguide portion, one on each side of the ribbed waveguide portion and on the insulation layer. The slab portion have higher doping concentrations than the respective doping concentrations in the ribbed waveguide portion. At least a portion of each slab portion has a height increasing with distance from the waveguide portion, with the slab height being smaller than that of the waveguide portion at the junction between the waveguide portion and slab portion. A pair of contact portions are formed adjacent the respective slab portion and further away from the waveguide portion. A portion of each contact portion can also have a height varying with distance from the waveguide portion.

An injection modulator for modulation of optical radiation, having an optical waveguide and a diode structure, having at least two p-doped semiconductor portions, at least two n-doped semiconductor portions and at least one lightly or undoped intermediate portion between the p-doped and n-doped portions. The p-doped portions when viewed in the longitudinal direction of the waveguide are offset with respect to the n-doped portions and the diode structure is arranged in a resonance-free portion of the waveguide. The p-doped portions lie on one side of the waveguide, the n-doped portions lie on the other side of the waveguide and the intermediate portion lies in the center, each portion extends transversely with respect to the waveguide longitudinal direction in the direction of the waveguide center of the waveguide and no p-doped portion when viewed in the longitudinal direction of the waveguide overlaps any n-doped portion.

A method of fabricating an optical structure comprises providing a layer of single crystal crystalline silicon supported on an insulating surface of a silicon substrate; using etching to remove part of the silicon layer and define a side wall which is non-parallel to the insulating surface of the substrate; forming a layer of insulating material over the side wall; forming a further layer of silicon over at least the insulating material; and removing the silicon of the further layer to a level of the layer of silicon such that the layer of insulating material occupies a slot between a portion of silicon in the layer and a portion of silicon in the further layer, a thickness of the layer of insulating material defining a width of the slot.

An optical device includes a first waveguide that propagates light in a first direction; and a second waveguide including a first mirror, a second mirror, and an optical waveguide layer. The first mirror extends in the first direction and has a first reflecting surface, and the second mirror extends in the first direction and has a second reflecting surface. The optical waveguide layer is located between the first and second mirrors and propagates the light in the first direction. A forward end portion of the first waveguide is disposed inside the optical waveguide layer. In a region in which the first and second waveguides overlap each other when viewed in a direction perpendicular to the first reflecting surface, at least part of the first waveguide and/or at least part of the second waveguide includes at least one grating whose refractive index varies periodically in the first direction.

A lithium niobate waveguide having weak phase drift includes a lithium niobate layer, a metal electrode, and a substrate layer. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extension surfaces extending towards two sides of the lithium niobate central ridge. A metal oxide layer is arranged on the upper surface of the lithium niobate central ridge. The substrate layer is located on the lower surface of the lithium niobate layer and is made of silicon, silicon dioxide, a multilayer material made of silicon and silicon dioxide or a multilayer material made of silicon dioxide, metal, and silicon, so as to further realize the purpose of inhibiting phase drift. Compared with other doped structures or other structures, the structure is simple in manufacturing method, and moreover, a very good phase drift suppression effect is achieved.

A light modulator according to the invention includes an optical waveguide formed of a material having an electro-optic effect, a buffer layer formed on the optical waveguide, and a pair of electrodes formed on the buffer layer, the width in the direction, in which the pair of electrodes are opposed to each other, of the buffer layer located on the side of the electrodes opposed to the optical waveguide is smaller than the width in the direction, in which the pair of electrodes are opposed to each other, of the buffer layer located on the optical waveguide side.

The optical device includes an optical modulator positioned on a base. The modulator includes a ridge extending upward from the base. The ridge includes an electro-absorption medium through which light signals are guided. A thermal conductor is positioned so as to conduct thermal energy away from the ridge. The distance between the thermal conductor and the ridge changes along a length of at least a portion of the ridge.

An optoelectronic device, including: a rib waveguide, the rib waveguide including: a ridge portion, which includes a temperature-sensitive optically active region, and a slab portion, positioned adjacent to the ridge portion; the device further comprising a heater, disposed on top of the slab portion wherein a part of the heater closest to ridge portion is at least 2 μm away from the ridge portion. The device may also have a heater provided with a bottom cladding layer, and may also include various thermal insulation enhancing cavities.

An optical phase shifter and a method of making the same are disclosed. The phase shifter includes a substrate, a p-doped electrode and an n-doped electrode on the substrate, a first doped semiconductor layer on the p-doped electrode or the n-doped electrode and in electrical contact with the other electrode, a second doped semiconductor layer on the first doped semiconductor layer, a first vertical region electrically connecting the second doped semiconductor layer with the one electrode, and a cladding layer on or over the second semiconductor layer, the first vertical region, and at least a first sidewall of each of the first and second semiconductor layers. The p-doped electrode and the n-doped electrode form a p-n junction at an interface therebetween. The first and second doped semiconductor layers have the same doping type as the other electrode and the one electrode, respectively.

An optical modulator includes: a substrate; a waveguide layer including first and second optical waveguides formed of an electro-optic material film on the substrate to have a ridge shape and to be disposed adjacent to each other; an RF part that applies a modulated signal to the optical waveguides; and a DC part that applies a DC bias to the optical waveguides. The DC part includes: a buffer layer covering at least upper surfaces of the optical waveguides; a first bias electrode opposed to the first optical waveguide through the buffer layer; and a second bias electrode provided adjacent to the first bias electrode. A first DC bias voltage is applied between the first and second bias electrodes. A waveguide layer removal area in which at least part of the waveguide layer is removed is provided at least under an area between the first and second bias electrodes.