In one embodiment, the invention relates to an apparatus for increasing the repetition rate in a light source. The apparatus includes a first optical coupler comprising a first arm, a second arm and a third arm; a first mirror in optical communication with the second arm of the first optical coupler; and a first optical delay line having a first end in optical communication with the third arm of the first optical coupler and a second end in optical communication with a second mirror, wherein light entering the first arm of the first optical coupler leaves the first arm of the first optical coupler either delayed by an amount (τ) or substantially undelayed.

Optical Buffering Methods, Apparatus, and Systems for Increasing the Repetition Rate of Tunable Light Sources

In at least one embodiment, the wavelength-tunable light source (1) comprises an output source (2) suitable for generating an electromagnetic beam (R) during operation. The light source (1) further comprises a wavelength-selective first filter element (5) disposed downstream of the output source (2). The light source (1) also comprises a first amplifier medium (3) disposed downstream of the first filter element (5) and suitable for at least partially amplifying the beam (R) emitted by the output source (2). The light source (1) further comprises at least one wavelength-selective second filter element (6) disposed downstream of the first amplifier medium (3), wherein the second filter element (6) has an optical distance (L) to the first filter element (5). The first (5) and the at least one second filter element (6) can be tuned using a control unit (11) that comprises the light source (1). In the process, the filter elements (5, 6) are tuned such that the first (5) and the second filter element (6) are transparent for part (P) of the beam (R) in a time delay (T) relative to one another, wherein the delay (T) is equal to the quotient of the optical distance (L) and the speed of light in a vacuum (c).

Wavelength-tunable light source

In one embodiment, the invention relates to systems, methods and devices for improving the operation of an electromagnetic radiation source or component thereof. In one embodiment, the source is a laser source. A Fourier domain mode locked laser can be used in various embodiments. The sources described herein can be used in an optical coherence tomography (OCT) system such as a frequency domain OCT system. In one embodiment, laser coherence length is increased by compensating for dispersion. A frequency shifter can also be used in one embodiment to compensate for a tunable filter induced Doppler shift.

Methods, systems, and devices for timing control in electromagnetic radiation sources

The present invention relates to a sensor or the like having a structure that enables accurate temperature measurement in a wide temperature range including a low-temperature region and is suitable for independently and accurately determining temperature variations and strains appearing in an object to be measured. The sensor comprises a laser light source, a sensor section that has a plurality of waveguides transmitting a laser light from the laser light source therethrough, a detecting section, and an analyzing section. The detecting section detects a plurality of Brillouin spectra obtained from the sensor section. The analyzing section determines at least one measurement value of a temperature in the sensor section and a strain generated in the sensor section, based on fluctuations of parameters defining the respective detected Brillouin spectra. In particular, the sensor section has a structure such that the variation of the Brillouin spectrum in response to a disturbance differs between the waveguides. Thus, by simultaneously monitoring the Brillouin spectra that varying a different manner in a plurality of waveguides, it is possible not only to measure accurately the temperature in a wide temperature range including a low-temperature region, but also to make distinction between the strain and temperature.

Sensor and disturbance measurement method using the same

An optical sensor includes a support structure. An optical fiber has a plurality of bends arranged proximate the support structure. The optical fiber follows a circuitous path and is adapted to establish a detection zone.

Fiber-optic mat sensor

A spatially distributed sensor system has an optical transmitter, an optical conduit optically coupled to the optical transmitter at an input position, and a sensing element optically coupled to the optical conduit at a position along the optical conduit spatially separated from the input position. The sensing element is structured to split off a fraction of light from the optical transmitter upon being coupled into the optical conduit and to return light to the optical conduit. The spatially distributed sensor system also has an optical receiver coupled to the optical conduit to receive at least a portion of light from the optical conduit that includes light returned to the optical conduit from the sensing element. An analysis of light received by the optical receiver provides information to determine a position of the sensing element.

Distributed fiber optic sensor with location capability

A single sweep polarization dependent loss measurement is achieved by causing a state of polarization of a test light source to rotate over a Poincare sphere as a function of optical wavelength of the test light source as a range of optical wavelengths is swept. Measurements of the state of polarization and optical power at the input and output of an optical component being tested together with the known optical wavelength for the state of polarization, taken at four different orientations of the state of polarization, provide a set of measurement data that is used to compute the polarization dependent loss for the optical component. A polarization scan module, in either an all-passive or active configuration, is used to produce the state of polarization as a function of optical wavelength for the test light source. The polarization scan module includes a swept-wavelength optical source and either an active polarization controller or passive optical elements to provide the rotation of the state of polarization over the Poincare sphere as a function of optical wavelength. The passive elements may be either polarization maintaining fibers oriented preferably at about 45° to the respective eigen states of each other and the optical source, the PMFs having different optical lengths, or optical splitter/multiplexer pairs having different optical path lengths between the splitter and multiplexer in each pair, the difference between path lengths being different in each pair. The relative orientation and lengths are chosen such that the state of polarization rotates over the Poincare sphere.

Single sweep polarization dependent loss measurement

An optical detection system includes an optical transmit-receive system, an optical conduit in optical communication with the optical transmit-receive system, and an optical sensor in optical communication with the optical conduit. The optical transmit-receive system provides pulsed optical signals to the optical sensor by way of the optical conduit that have a maximum pulse width of about 100 nanoseconds and further have a maximum pulse width that is less than a maximum distance of reflection of the pulsed optical signals in the optical detection system to decrease false alarms.

Method and apparatus for reducing noise in a fiber-optic sensor

A single sweep polarization dependent loss measurement is achieved by causing a state of polarization of a test light source to rotate over a Poincare sphere as a function of optical wavelength of the test light source as a range of optical wavelengths is swept. Measurements of the state of polarization and optical power at the input and output of an optical component being tested together with the known optical wavelength for the state of polarization, taken at four different orientations of the state of polarization, provide a set of measurement data that is used to compute the polarization dependent loss for the optical component. A polarization scan module, in either an all-passive or active configuration, is used to produce the state of polarization as a function of optical wavelength for the test light source. The polarization scan module includes a swept-wavelength optical source (12) and either an active polarization controller or passive optical elements to provide the rotation of the state of polarization over the Poincare sphere as a function of optical wavelength. The passive elements may be either polarization maintaining fibers (14,16) oriented preferably at about 45° to the respective eigen states of each other and the optical source (12), the PMFs (14,16) having different optical lengths (L , √ 2), or optical splitter/multiplexer pairs having different optical path lengths between the splitter and multiplexer in each pair, the difference between path lengths being different in each pair. The relative orientation and lengths are chosen such that the state of polarization rotates over the Poincare sphere.

Shailesh Singh

Papers

Distributed fiber optic sensor with location capability

Single sweep polarization dependent loss measurement

Method and apparatus for reducing noise in a fiber-optic sensor

Single wavelength sweep polarization dependent loss measurement