To provide an optical signal processing device capable of reducing the crosstalk while narrowing the space between switch elements for downsizing, the optical signal processing device includes a plurality of input optical waveguides, a plurality of output optical waveguides, a plurality of optical waveguide elements arranged between the plurality of input optical waveguides and the plurality of output optical waveguides, and a connection optical waveguide. The connection optical waveguide positioned closely to the optical waveguide element is differentiated in propagation constant from the optical waveguide configuring the closely arranged optical waveguide element. The connection optical waveguide positioned closely to the optical waveguide element is a connection optical waveguide having one end or both ends connected to the optical waveguide element, or a connection optical waveguide having both ends not connected to the optical waveguide elements.

A wavelength demultiplexing device configured so as to spatially distributing the spectral contributions of an incident light beam, when in use, and which includes a linear waveguide and a planar waveguide, formed in a coplanar way and adapted to be optically coupled with one another along a coupling line, by evanescent coupling. Such a device may further include diffraction gratings located in the planar waveguide, to extract light out of the latter.

An optical phase shifter may include a waveguide core that has a top surface, and a semiconductor contact that is laterally displaced relative to the waveguide core and is electrically connected to the waveguide core. A top surface of the semiconductor contact is above the top surface of the waveguide core. The waveguide core may include a p-type core region and an n-type core region. A p-type semiconductor region may be in physical contact with the n-type core region of the waveguide core, and an n-type semiconductor region may be in physical contact with the p-type core region of the waveguide core. A phase shifter region and a light-emitting region may be disposed at different depth levels, and the light-emitting region may emit light from a phase shifter region that is in a position adjacent to the light-emitting region.

An optical phase shifter may include a waveguide core that has a top surface, and a semiconductor contact that is laterally displaced relative to the waveguide core and is electrically connected to the waveguide core. A top surface of the semiconductor contact is above the top surface of the waveguide core. The waveguide core may include a p-type core region and an n-type core region. A p-type semiconductor region may be in physical contact with the n-type core region of the waveguide core, and an n-type semiconductor region may be in physical contact with the p-type core region of the waveguide core. A phase shifter region and a light-emitting region may be disposed at different depth levels, and the light-emitting region may emit light from a phase shifter region that is in a position adjacent to the light-emitting region.

An optical phase shifter may include a waveguide core that has a top surface, and a semiconductor contact that is laterally displaced relative to the waveguide core and is electrically connected to the waveguide core. A top surface of the semiconductor contact is above the top surface of the waveguide core. The waveguide core may include a p-type core region and an n-type core region. A p-type semiconductor region may be in physical contact with the n-type core region of the waveguide core, and an n-type semiconductor region may be in physical contact with the p-type core region of the waveguide core. A phase shifter region and a light-emitting region may be disposed at different depth levels, and the light-emitting region may emit light from a phase shifter region that is in a position adjacent to the light-emitting region.

Aspects described herein include an optical waveguide emitter that includes a first optical waveguide and a second optical waveguide that are evanescently coupled and collectively configured to selectively propagate only a first mode of a plurality of optical modes. Each of the first optical waveguide and the second optical waveguide extend through an input waveguide section, a turning waveguide section, and an output waveguide section. One or more of the input waveguide section, the turning waveguide section, and the output waveguide section includes an optically active region. The optical waveguide emitter further includes a refractive index-increasing feature in the turning waveguide section.

A method for producing a semiconductor optical device includes the steps of bonding a semiconductor chip to an SOI substrate having a waveguide, the semiconductor chip having an optical gain and including a first cladding layer, a core layer, and a second cladding layer that contain III-V group compound semiconductors and are sequentially stacked in this order, forming a covered portion with a first insulating layer on the second cladding layer, etching partway in the thickness direction the second cladding layer exposed from the first insulating film, forming a second insulating film covering from the covered portion to a part of a remaining portion of the second cladding layer, and forming a first tapered portion that is disposed on the waveguide and tapered along the extending direction of the waveguide by etching the core layer and the second cladding layer exposed from the second insulating film.

Aspects described herein include an optical waveguide emitter that includes a first optical waveguide and a second optical waveguide that are evanescently coupled and collectively configured to selectively propagate only a first mode of a plurality of optical modes. Each of the first optical waveguide and the second optical waveguide extend through an input waveguide section, a turning waveguide section, and an output waveguide section. One or more of the input waveguide section, the turning waveguide section, and the output waveguide section includes an optically active region. The optical waveguide emitter further includes a refractive index-increasing feature in the turning waveguide section.

An object of the present invention is to provide a probe optical fiber and a local-light coupling apparatus for an optical fiber that can input light with high efficiency without performing input efficiency measurement or probe alignment. The present invention is a probe optical fiber of which a tip is close to a bent part of a coated optical fiber disposed in a local-light coupling apparatus for an optical fiber, and which inputs and outputs light to and from the bent part of the coated optical fiber, wherein light emitted from the tip has a light intensity profile in which in the bent part of the coated optical fiber, relative to a light intensity in a center of an optical axis, a decrease in light intensity at a position separated by 20 μm from the optical axis is less than 17.6 dB.

An optical phase shifter may include a waveguide core that has a top surface, and a semiconductor contact that is laterally displaced relative to the waveguide core and is electrically connected to the waveguide core. A top surface of the semiconductor contact is above the top surface of the waveguide core. The waveguide core may include a p-type core region and an n-type core region. A p-type semiconductor region may be in physical contact with the n-type core region of the waveguide core, and an n-type semiconductor region may be in physical contact with the p-type core region of the waveguide core. A phase shifter region and a light-emitting region may be disposed at different depth levels, and the light-emitting region may emit light from a phase shifter region that is in a position adjacent to the light-emitting region.