A first photonics integrated circuit (PIC) chip originates from a PIC wafer. The first PIC chip includes a substrate, and one or more optical communication components fabricated on the substrate. Optical testing components are also fabricated on the substrate. The optical testing components are configured to, prior to die singulation of the PIC wafer, transfer light to a second PIC chip on the PIC wafer for testing one or more operational attributes of optical components disposed on the second PIC chip Prior to die singulation of the PIC wafer, the second PIC chip was adjacent to the first PIC chip on the PIC wafer.

A computer-implemented method in a processing device of an Optical Critical Dimension (OCD) metrology system includes receiving grating parameters as input to a neural network. The neural network generates an output including a predicted optical response of a grating based on the grating parameters. Responsive to determining that a difference between the predicted optical response and a measured optical response of the grating is within a specified threshold, the grating parameters are output as a predicted structure of the grating. Responsive to determining that the difference is greater than the specified threshold, the grating parameters received as input to the neural network are iteratively updated until the predicted optical response and the measured optical response converge.

A method and system for measuring signal loss in a fiber optic cable. The tail ends of reference and test fiber optic cables are illuminated with a diffuse light. The head end of each of the reference and test fiber optic cables are positioned in a measurement area. A core imager captures an image of the core of each head-end while it is in the measurement area. Reference and test radiant fluxes emitted from the reference and test head-ends are determined from the respective core images. The relative signal loss of the test fiber optic cable is then determined by comparing the test radiant flux to the reference radiant flux.

Systems and methods for inspecting wound optical fiber to detect and characterize defects are disclosed. The method includes illuminating the wound optical fiber with light from a light source and capturing a digital image based on measurement light that is redirected by the wound optical fiber to a digital camera. The method also includes processing the digital image with a computer to detect and characterize the defects. The types of defects that can be detected using the systems and methods disclosed herein include bubbles, abrasions, punctures, scratches, surface contamination, winding errors, periodic dimensional errors, aperiodic dimensional errors and dents.

Techniques are provided for controlling azimuthal alignment of a cross-section of the anti-resonant hollow core fiber when winding such anti-resonant hollow core fiber into a coil.

A method for determining the refractive index profile of a preform when the RIP is not substantially symmetrical. (i) The preform is scanned, starting with a first projection angle, and raw data are created representing the object through measured data. (ii) Optionally, the object is rotated and step (i) repeated iteratively until all projection angles have been scanned and all measured data have been created. (iii) The measured data are processed to form a sinogram and, if the optional step (ii) has been completed, the method proceeds to step (v). (iv) The object is rotated and steps (i) and (iii) are repeated iteratively until all projection angles have been scanned. (v) A 2D RIP is calculated. (vi) A line section of interest is selected within the 2D RIP. (vii) A fitting procedure is applied to the line section of interest. (viii) Finally, refractive index steps/gradients and dimensions are determined.

Examining a light optical element (LOE) may include placing a first slit optically between a projector configured to emit light and the LOE's first major surface and placing a second slit optically between the LOE's second major surface and a detector. Facet parallelism between two facets may be deduced based on a shift of the image reflected from the first facet to the second facet relative to light transmitted normal to the first and second major surfaces through a portion of the substrate not including a facet. Facet refractive index homogeneity or deviation may be deduced based on the light transmitted through the facet relative to light transmitted normal to the first and second major surfaces through a portion of the substrate not including a facet.

A method of calculating an indicator of a thin wire according to the present disclosure includes: obtaining X-ray images of a plurality of cross sections of a cable having a plurality of thin wires, the plurality of cross sections being perpendicular to a long-side direction of the cable; finding a central position of each of the plurality of thin wires from each of the X-ray images of the plurality of cross sections; and finding an indicator representing a curve of each thin wire based on the central position of the thin wire.

An inspection method, for an optical fiber including a bare optical fiber and a light-transmitting coating layer that coats an outer peripheral surface of the bare optical fiber, includes: irradiating, with illumination light having directivity, an outer peripheral surface of a wound body that includes the optical fiber wound in multiple layers around a bobbin; receiving the illumination light reflected by the wound body and generating image data containing at least a part of an image of the illumination light; and determining, based on the image data, whether a stripe pattern is projected in the image. The stripe pattern is a state in which the illumination light repeatedly changes along a winding direction of the optical fiber.

System and method for determining distributed birefringence variations in a polarization-maintaining optical fiber (PM fiber). The method includes causing a pump signal to be sent into the PM fiber to generate a Brillouin dynamic grating (BDG) therein, causing a first chirped probe optical pulse to be sent into the PM fiber, receiving a first reflected signal, the first reflected signal being a first portion of the first chirped probe optical pulse reflected by the BDG, receiving a second reflected signal, the second reflected signal being a second portion of the first chirped probe optical pulse reflected by the BDG, and determining a variation of birefringence of the PM fiber indicative of a variation of physical disturbance of the PM fiber between times of reflections on the BDG of the first and second reflected signals.