An apparatus, and related method, relates generally to a fiber-optic sensing system. In such a system, fiber-optic sensors are in a rosette or rosette-like pattern. An optical circulator is coupled to receive a light signal from a broadband light source, to provide the light signal to the fiber-optic sensors, and to receive a returned optical signal from the fiber-optic sensors. A spectral engine is coupled to the optical circulator to receive the returned optical signal and configured to provide an output signal.

A direct modulation laser includes a distributed feedback type laser active region and an optical feedback region optically connected to one end of the laser active region in a waveguide direction. The direct modulation laser performs laser oscillation by using photon-photon resonance (PPR) that occurs depending on a frequency difference between a frequency of light generated (oscillated) in the laser active region and a frequency of an FP mode in the optical feedback region.

A test device and method for testing a distributed feedback laser diode (DFB-LD) device for an optical transceiver of a radio over fiber (RoF) system examines the DFB-LD device based on an absolute limiting rating, an operating case environment, and a functional specification, in which the absolute limiting rating is a rating at which there is no fatal damage to the DFB-LD device during a short period of time when each limiting parameter is isolated and all other parameters are in a normal performance parameter, the operating case environment includes an operating temperature, and the functional specification includes parameters to be tested according to an operating condition for the functional specification.

A semiconductor light emitter includes a substrate, a semiconductor multilayer structure including a light emission unit that emits light in an oblique direction with respect to the substrate in an emission region in a longitudinal direction and a lateral direction orthogonal to the longitudinal direction, and a shaping optical system that shapes a luminous flux emitted from the light emission unit, in which a lens closest to the light emission unit in the shaping optical system is a cylindrical lens having positive power in the lateral direction, a front major plane of the cylindrical lens is parallel to the light emission unit and a generatrix direction of the cylindrical lens is parallel to the longitudinal direction, and the following conditional equation (1) is satisfied in a case where a distance from the light emission unit to a light incident surface of the cylindrical lens is D, a distance from the light incident surface to the front major plane of the cylindrical lens is HA, and a focal length of the cylindrical lens is f,

D<f−HA  (1).

A Bragg grating includes a lower waveguide layer, a middle waveguide layer disposed on the lower waveguide layer, an upper waveguide structure disposed on the middle waveguide layer opposite to the lower waveguide layer, and a buried layer. The upper waveguide structure includes upper waveguide elements that are arranged on a surface of the middle waveguide layer, and that are spaced apart from one another by cavities. The buried layer fills the cavity. The middle waveguide layer has a refractive index lower than that of each of the lower waveguide layer and the upper waveguide elements. The lower waveguide layer has a doping type the same as that of the middle waveguide layer. A method for manufacturing the Bragg grating is also provided.

A semiconductor optical device includes a light emitting layer that emits light in a state of current injection; an optical waveguide in which a width or a thickness in an extending direction (y) of the light emitting layer varies along the extending direction; and a uniform diffraction grating having constant cycle, width and depth, wherein the light emitting layer, the optical waveguide and the uniform diffraction grating are arranged at positions where the light emitting layer, the optical waveguide, and the uniform diffraction grating are optically coupled to one another, the uniform diffraction grating is arranged above the light emitting layer, the optical waveguide is arranged below the light emitting layer, and the optical waveguide includes, in the extending direction, a first portion having a predetermined width, a second portion having a larger width than the width of the first portion, and a third portion having the same width as the width of the first portion.

A laser device for use with a display including a plurality of pixels is disclosed. The laser device includes a gain section and a modulator. The gain section is electrically coupled with a first current or voltage source. The gain section is configured to selectively amplify an optical power of light reflecting within the gain section based on a first drive current or voltage supplied from the first current or voltage source to the gain section. The modulator is optically coupled with the gain section. The modulator is electrically coupled with a second current or voltage source. The modulator is configured to selectively attenuate or amplify an optical power of light received from the gain section based on a second drive current or voltage supplied from the second current or voltage source to the modulator. Light emitted from the modulator is provided to the display.

A laser device for use with a display including a plurality of pixels is disclosed. The laser device includes a gain section and a modulator. The gain section is electrically coupled with a first current or voltage source. The gain section is configured to selectively amplify an optical power of light reflecting within the gain section based on a first drive current or voltage supplied from the first current or voltage source to the gain section. The modulator is optically coupled with the gain section. The modulator is electrically coupled with a second current or voltage source. The modulator is configured to selectively attenuate or amplify an optical power of light received from the gain section based on a second drive current or voltage supplied from the second current or voltage source to the modulator. Light emitted from the modulator is provided to the display.

A method or apparatus for narrowing the linewidth of a single mode laser is provided. The linewidth of a single mode laser is narrowed by injecting an optical feedback simultaneously into the first laser cavity mirror and the second laser cavity mirror of the single mode laser.

A method or apparatus for narrowing the linewidth of a single mode laser is provided. The linewidth of a single mode laser is narrowed by injecting an optical feedback simultaneously into the first laser cavity mirror and the second laser cavity mirror of the single mode laser.