Disclosed herein is a method for measuring temperature via distributed temperature sensing comprising transmitting light through a fiber optic cable; detecting backscattered light in the fiber optic cable, wherein the backscattered light comprises an anti-Stokes band and a Stokes band; calculating a ratio between an intensity of the anti-Stokes band and an intensity of the Stokes band; and using the calculated ratio to determine a temperature being sensed in the fiber optic cable; wherein the fiber optic cable comprises, from the center to the periphery; a central core having a refractive index that decreases progressively from a center of the central core to an edge of the core, wherein the refractive index follows an alpha profile; wherein a bandwidth-length product of the multimode optical fiber has a value greater than 2000 MHz-km at 1550 nm.

A grating coupled laser (GCL) includes an active section and a passive section. The passive section is butt coupled to the active section to form a butt joint with the active section. The active section includes an active waveguide. The passive section includes a passive waveguide, a transmit grating coupler, and a top cladding. The passive waveguide is optically coupled end to end with the active waveguide and includes a first portion and a second portion. The first portion of the passive waveguide is positioned between the second portion of the passive waveguide and the active waveguide. The transmit grating coupler is optically coupled to the passive waveguide and includes grating teeth that extend upward from the second portion of the passive waveguide. The top cladding is positioned directly above the first portion of the passive waveguide and is absent directly above at least some of the transmit grating coupler.

A method of fabricating a gyrotropic device (e.g., an optical isolator) includes: providing a substrate comprising a waveguide layer and forming an optical isolator active layer on the waveguide layer of the substrate. Forming the optical isolator active layer includes, for a specified composition of the optical isolator active layer, deriving at least one sputtering process parameter, performing sputtering of a plurality of targets according to the at least one sputtering process parameter to deposit the optical isolator active layer on the waveguide layer of the substrate, measuring an initial value of a bias voltage at a first target of the plurality of targets; and throughout deposition of the optical isolator active layer, maintaining the bias voltage at the initial value to within a predetermined threshold of the initial value.

Multi-stage fiber amplifiers can amplify signals from a few Watts to several kilowatts. These amplifiers are limited in power by intensity instabilities resulting from a sequence of nonlinear optical effects. These nonlinear optical effects include stimulated Brillouin scattering (SBS), with produces a high-intensity pulse close to the signal wavelength that propagates backward up the amplifier chain, causing permanent damage to the upstream components. This SBS pulse can be blocked by an optical isolator that blocks backward-propagating light at or near the signal wavelength. At high enough power levels, the SBS pulse can also induce backward-propagating light at wavelengths tens to hundreds of nanometers away from the signal wavelength. This SBS-Pulse Induced Non-linear Spectrum light is outside the isolator's reject band, so it can propagate upstream and de-stabilize the upstream amplifier stages. It can be suppressed using a filter with a broad reject band and a suppression ratio of ≥30 dB, enabling higher power operation.

An optical semiconductor device comprises: a first wiring pattern provided on a carrier mounting surface of a dielectric substrate; a first reference potential pattern surrounding the first wiring pattern; a carrier block provided on the carrier mounting surface and having a main surface, a side surface, and a second wiring pattern and a second reference potential pattern constituting coplanar lines; and an optical semiconductor element provided on the main surface. One end portion of the second wiring pattern extends to at least an end edge on the side surface side in the main surface and is conductively joined to the first wiring pattern with a conductive joining material therebetween. One end portion of the second reference potential pattern extends to at least the end edge on the side surface side in the main surface and is conductively joined to the first reference potential pattern with a conductive joining material therebetween.

An apparatus includes a fiber-optic connector configured to be connected between one or more optical fibers having a plurality of fiber cores and a photonic integrated circuit including a plurality of vertical-coupling elements disposed along a main surface of the photonic integrated circuit. The fiber-optic connector includes a polarization beam splitter and a patterned birefringent plate. The polarization beam splitter is configured to split an incident light beam from a corresponding fiber core into a first beam having a first polarization and a second beam having a second polarization different from the first polarization. The patterned birefringent plate includes a first region and a second region, the first region has a first optical birefringence, the second region has a second optical birefringence that is different from the first optical birefringence. The difference in the first and second optical birefringence is caused by performing at least one of (i) applying localized heating to the first region without applying localized heating to the second region to cause the first region to have a lower birefringence as compared to the second region, or (ii) applying different amounts of localized heating to the first and second regions to cause the first region to have a first birefringence and the second region to have a second birefringence different from the first birefringence.

An optical module of the present disclosure includes an optical element, a first optical component that is optically coupled to the optical element, a second optical component that is optically coupled to the first optical component, a receptacle to which an optical fiber that transmits the incident light to the second optical component is connected, a terminal unit that electrically outputs an output signal of the optical element to the outside, and a package that accommodates the optical element, the first optical component, and the second optical component and is provided with the receptacle on a first surface and the terminal unit on a second surface facing the first surface, wherein the wiring extends from the first surface side to the second surface side and electrically connects the second optical component and the terminal unit.

An optical module includes a housing, at least one optical assembly and at least one sealing member. The housing includes a housing body, a cover and at least one vent hole therein. At least part of each optical assembly is located in the housing body. Each sealing member is located at a respective one of the at least one vent hole. The sealing member has a central axis and includes a first cylinder, a truncated cone, and a second cylinder, a diameter of the first cylinder is greater than a diameter of the second cylinder. Each vent hole is a stepped hole including a portion with a first aperture and a portion with a second aperture, the first aperture is greater than the second aperture. The first cylinder fits the portion with the first aperture, and the second cylinder fits the portion with the second aperture.

Aspects described herein include a method including arranging a laser die on a substrate. The laser die has multiple channels that are arranged with a first planar arrangement proximate to a facet of the laser die. The substrate is arranged on a housing component. The method further includes aligning a single lens to the facet, and aligning a multicore optical fiber to the laser die through the single lens. The multicore optical fiber has a plurality of optical cores that are arranged with a second planar arrangement. Aligning the multicore optical fiber to the laser die includes attaching the multicore optical fiber to the housing component and rotationally aligning the multicore optical fiber to align the second planar arrangement with the first planar arrangement.

An apparatus includes a substrate. A laser is formed on a non-self supporting structure and bonded to the substrate. A waveguide having a gap portion is deposited proximate the laser. The waveguide is configured to communicate light from the laser to a near-field transducer (NFT) that directs energy resulting from plasmonic excitation to a recording medium. An optical isolator is disposed over the gap portion.