Time filter

Source Type

Chapin, NJ, United States

An arrangement for providing real-time, in-service OTDR measurements in an optical communication system utilizing distributed Raman amplification. One or more of the laser diodes used to provide the pump light necessary to create optical gain is modified to also generate short duration pulses that ride above or below the conventional pump light. These short duration pulses (which co-exist with the pump light within the optical fiber) are used in performing OTDR measurements, with a conventional processing system used to evaluate reflected pulses and create the actual OTDR measurements.

II VI Incorporated | Date: 2014-03-17

Disclosed is a method and apparatus for simultaneously polishing both surfaces of an optical substrate. An upper platen and a lower platen, each covered with a polishing pad material and at least one carrier having an aperture for holding the optical substrate between the platens are provided. The location of the aperture of the carrier is set such that the center of the optical substrate is offset from the center of the carrier and at least a portion of the outer perimeter of the optical substrate extends outwardly beyond at least a portion of at least one of the outer perimeter and the inner perimeter of the platens. The platens are rotated with respect to the carrier, and the carrier is rotated with respect to the platens to polish the optical substrate. The location of the aperture of the carrier is adjustable.

A crucible has a first resistance heater is disposed in spaced relation above the top of the crucible and a second resistance heater with a first resistive section disposed in spaced relation beneath the bottom of the crucible and with a second resistive section disposed in spaced relation around the outside of the side of the crucible. The crucible is charged with a seed crystal at the top of an interior of the crucible and a source material in the interior of the crucible in spaced relation between the seed crystal and the bottom of the crucible. Electrical power of a sufficient extent is applied to the first and second resistance heaters to create in the interior of the crucible a temperature gradient of sufficient temperature to cause the source material to sublimate and condense on the seed crystal thereby forming a growing crystal.

An OTDR system utilizes a laser source that is turned on and kept powered until its light reaches the end of the fiber span being measured (i.e., until the fiber span is fully illuminated). At any point in time after the fiber is fully illuminated, the laser source can be turned off. The return (reflected and backscattered) signal is directed into a photodetector of the OTDR, and is measured from the point in time when the fiber span starts to be illuminated. The measurements are made by sampling the return signal at predetermined time intervalsdefined as the sampling rate. The created power samples are then subjected to post-processing in the form of a differentiation operation to create a conventional OTDR trace from the collected data.

II VI Incorporated | Date: 2014-09-25

A tunable multiport optical filter includes various types of arrays of optical ports. The tunable filter also includes a light dispersion element (e.g., a grating) and a reflective beam steering element (e.g., a tilting mirror). An optical signal exits an optical (input) port, is dispersed by the light dispersion element, reflects off the reflective beam steering element back to the light dispersion element, and on to another optical (output) port. The reflective beam steering element can be steered such that a wavelength portion of the dispersed optical signal can be coupled to the optical output port. For example, the input optical signal may be a wavelength division multiplexed signal carrying multiple channels on different wavelengths, and the tunable multiport optical filter directs one of the channels to the output optical port. Additionally, the tunable filter may be incorporated into a device acting as a wavelength reference.

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