Abstract: An integrated optical switch that has a low throughput loss during the “on” pulse, and a high throughput loss during the “off” period. The optical switch includes a substrate with at least two waveguide structures suitably formed on the substrate. One of the waveguide structures is substantially straight and connects an input port to an output port. During an “on” pulse, light may be guided along the substantially straight waveguide from the input port to the output port such that there is little throughput loss. During an “off” period, a voltage is applied across control electrodes such that the waveguides are coupled so that light does not reach the output port.

Abstract: A fiber optic fault detector and generic fiber optic sensor system for detecting breaks in an optical fiber using a low coherence interferometric technique. The system comprises a light source configured to produce light traveling along the optical path, a modulator optically coupled to the light source configured to modulate at least a portion of the light as a function of a modulation signal, a detector optically coupled to the modulator configured to produce a detector output based upon a sensed intensity of the light, and an electronic array configured to receive the detector output and determine the optical fault. The low coherence interferometric technique allows for detection of a fault in the fiber with a minimal amount of test equipment and with higher measurement sensitivity and resolution. The system may alternatively include a transducer, positioned in place of the fiber under test, having a response which changes in reflective or optical path length.

Abstract: A method is provided for sensing an environmental effect upon a sensing element and includes exposing the sensing element into the environmental effect, producing a light signal in the sensing element, modulating the light signal with a modulation signal, and determining a path length of the light signal as a function of the modulation signal. A fiber optic sensor is provided that includes a light source producing a light, a sensing element optically coupled to the light source such that the light propagates through the sensing element, a detector optically coupled to the sensing element. The detector detects light intensity propagating in the sensing element. An electronics processor receives the detector output and produces a modulation signal for the light. The processor further produces an output signal indicative of the environmental effect as a function of the modulation signal.

Abstract: An example of a fiber optic light source has a pump laser that feeds light to a length of doped optical fiber. The optical fiber produces light that has a mean wavelength, for example in the range of 1515 nm to 1544 nm, such that the light is substantially unaffected when exposed to weapons level radiation.

Abstract: A method is provided for sensing an environmental effect upon a sensing element and includes exposing the sensing element into the environmental effect, producing a light signal in the sensing element, modulating the light signal with a modulation signal, and determining a path length of the light signal as a function of the modulation signal. A fiber optic sensor is provided that includes a light source producing a light, a sensing element optically coupled to the light source such that the light propagates through the sensing element, a detector optically coupled to the sensing element. The detector detects light intensity propagating in the sensing element. An electronics processor receives the detector output and produces a modulation signal for the light. The processor further produces an output signal indicative of the environmental effect as a function of the modulation signal.

Abstract: A fiber optic fault detector and generic fiber optic sensor system for detecting breaks in an optical fiber using a low coherence interferometric technique. The system comprises a light source configured to produce light traveling along the optical path, a modulator optically coupled to the light source configured to modulate at least a portion of the light as a function of a modulation signal, a detector optically coupled to the modulator configured to produce a detector output based upon a sensed intensity of the light, and an electronic array configured to receive the detector output and determine the optical fault. The low coherence interferometric technique allows for detection of a fault in the fiber with a minimal amount of test equipment and with higher measurement sensitivity and resolution. The system may alternatively include a transducer, positioned in place of the fiber under test, having a response which changes in reflective or optical path length.

Abstract: A new apparatus and method designed to protect an interferometric fiber optic light source from weapons level radiation threat is provided. A fiber optic light source is configured to produce a light spectrum which has a mean wavelength which is substantially unaffected when exposed to weapon's level radiation threat. The fiber optic light source is configured to produce a light output with a mean wavelength in the range of 1520 nm to 1540 nm, and is preferably configured to produce a light output with mean wavelength of about 1532 nm. The fiber optic light comprises a pump laser and a length of doped fiber optic material through which light from the pump laser is directed. The length of fiber optic material has a configuration which produces a light output with a predetermined spectrum and mean wavelength. The length of fiber optic material will depend on the specific properties of the fiber, but with the preferred material, i.e.

Abstract: An integrated optical switch that has a low throughput loss during the “on” pulse, and a high throughput loss during the “off” period. The optical switch includes a substrate with at least two waveguide structures suitably formed on the substrate. One of the waveguide structures is substantially straight and connects an input port to an output port. During an “on” pulse, light may be guided along the substantially straight waveguide from the input port to the output port such that there is little throughput loss. During an “off” period, a voltage is applied across control electrodes such that the waveguides are coupled so that light does not reach the output port.

Abstract: A system is disclosed which suppresses relative intensity noise in a fiber optic gyroscope. A high-speed intensity modulator is placed in the gyroscope light path between the fiber light source and a tap coupler which provides a sample of the modulated signal for use in a feedback loop. A photodetector receives the sampled signal and provides current-to-voltage conversion of the signal. A high-bandwidth voltage amplifier then adjusts the gain and phase of the converted signal and drives the intensity modulator in such a manner as to stabilize the control loop and provide suppression of relative intensity noise. The present system modulates the intensity of the light at a frequency which is sufficiently high to allow suppression of high frequency components of the relative intensity noise.

Abstract: A fiber light source having, for instance, a 980 nm pump laser for pumping an erbium-doped optical fiber via a 980/1550 nm WDM coupler. The pumped fiber emits 1550 nm light. A portion of the 1550 nm light goes to a filter via the WDM coupler. The filter shapes the spectrum of the 1550 nm light. The filter is a passive device that may be made from erbium-doped fiber. From the filter the 1550 nm light goes through an isolator or a circulator on to an optical device for which the light is specially made. Such device may be an fiber optic gyroscope. By adding a narrowband optical fiber grating at the output of the pump laser to tune its output, the fiber light source is further improved in stability under variations of ambient temperature and light source drive current.

Abstract: A piezoelectric fiber optic phase modulator having a mount at a nodal point of the vibratory system of the modulator. The modulator is excited with an electric field applied in a direction parallel to the axis of the modulator or perpendicular to the radial direction of movement of the modulator. In contrast to the mere hollow cylinder modulator of the related art, the modulator of this invention has a web or center structure integral with the inside surface of the cylinder. The modulator here has a rugged mount, low absorption vibration and negligible harmonics at the mount for efficient and high Q functioning, and has rugged electrical connections for dependable operation.

Abstract: An error control arrangement for an optical fiber rotation sensor having electromagnetic waves propagating in opposite directions passing through a bias optical phase modulator operated by a phase modulation generator both of which can contribute second harmonic distortion resulting in errors in the sensor output signal which are controlled. Control of the bias optical phase modulator contribution for a modulator having a piezoelectric body wrapped with an optical fiber portion is accomplished by mounting the body utilizing layers having nonlinear stiffness.