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 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.

An optical device may include a waveguide-based Mach-Zehnder (MZ) interferometer associated with performing polarization multiplexing or demultiplexing. The waveguide-based MZ interferomenter may include a first MZ arm, a second MZ arm, and a set of stress-balancing trenches. A portion of the first MZ arm may be between at least two stress-reducing trenches of a plurality of stress-reducing trenches. The plurality of stress-reducing trenches may be in a cladding layer on a substrate. The set of stress-balancing trenches may be on an opposite side of the second MZ arm from the plurality of stress-reducing trenches. The set of stress-balancing trenches may be in the cladding layer on the substrate.

An object of the present invention is to provide is an optical laminate film exhibiting excellent reflection tint and an organic EL display device using this optical laminate film and exhibiting excellent reflection tint when turned off. The object is achieved by providing an optical laminate film including a polarizer, a phase difference layer, and a circularly polarized light separating layer in this order, in which an in-plane retardation Re(550) of the phase difference layer is 120 to 160 nm, the polarizer and the phase difference layer are arranged to form an angle of 4510, the circularly polarized light separating layer is a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystalline phase and having a liquid crystalline molecule as a main component, and Re(550) is 0.5 to 3.0 nm, and an optical laminate film in which a circularly polarized light separating layer has an in-plane phase difference and an angle formed between a slow axis of a phase difference layer and a slow axis of the circularly polarized light separating layer is 30 to 30.

A cadmium free quantum dot including a semiconductor nanocrystal core and a semiconductor nanocrystal shell disposed on the core, wherein the quantum dot does not include cadmium and includes indium and zinc, the quantum dot has a maximum photoluminescence peak in a red light wavelength region, a full width at half maximum (FWHM) of the maximum photoluminescence peak is less than or equal to about 40 nanometers (nm), an ultraviolet-visible (UV-Vis) absorption spectrum of the quantum dot includes a valley between about 450 nm to a center wavelength of a first absorption peak, and a valley depth (VD) defined by the following equation is greater than or equal to about 0.2, a quantum dot polymer composite including the same, and a display device including the quantum dot-polymer composite:

(Abs.sub.firstAbs.sub.valley)/Abs.sub.first=VD.

Provided is an optical device including a radio frequency (RF) signal source configured to electrically provide an RF signal, a first diode configured to operate as a laser diode (LD) or an electro-absorption modulator (EAM) in response to the RF signal, a second diode configured to share an N region of the first diode, be serially connected to the first diode, and have a P region connected to a ground to operate as a capacitor for series push-pull operation with the first diode, and a resistor connected between the N region and the ground.

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.

A cadmium free quantum dot including a semiconductor nanocrystal core and a semiconductor nanocrystal shell disposed on the core, wherein the quantum dot does not include cadmium and includes indium and zinc, the quantum dot has a maximum photoluminescence peak in a red light wavelength region, a full width at half maximum (FWHM) of the maximum photoluminescence peak is less than or equal to about 40 nanometers (nm), an ultraviolet-visible (UV-Vis) absorption spectrum of the quantum dot includes a valley between about 450 nm to a center wavelength of a first absorption peak, and a valley depth (VD) defined by the following equation is greater than or equal to about 0.2, a quantum dot polymer composite including the same, and a display device including the quantum dot-polymer composite:
(Abs.sub.firstAbs.sub.valley)/Abs.sub.first=VD.

An optical waveguide modulator with automatic bias control is disclosed. A portion of the modulator light is mixed with reference light and converted to one or more electrical feedback signals. An electrical feedback circuit controls the modulator bias responsive to the feedback signals.