Abstract: A method includes generating a sequence of multiple optical pulses, for transmission into an optical fiber (12) having an array of multiple equally spaced reflectors (14) embedded therein, the sequence having a pulse duration and a pulse repetition interval (PRI) that guarantee that reflections of any of the optical pulses from any of the reflectors do not overlap. The sequence of optical pulses is transmitted into the optical fiber. The reflections of the optical pulses from the reflectors are extracted from the optical fiber. One or more events affecting the optical fiber are identified by analyzing the reflections.

Abstract: A method for estimating a geometrical shape of an optical fiber (106) includes transmitting (102) into the optical fiber an input optical signal that excites in the optical fiber multiple propagation modes. An output optical signal, which is output from the optical fiber in response to the input optical signal, is recombined with a reference signal derived from the input optical signal, so as to produce a recombined optical signal. The recombined optical signal is detected (108), and the geometrical shape of the optical fiber (106) is estimated based on the detected recombined optical signal.

Abstract: A method for transmitting information includes deriving a transfer function that relates a first image formed over a first area on an end face (38) of a multimode optical fiber (40) and a second image formed over a second area extending over a side (42) of the multimode optical fiber. Optical information is input to the multimode optical fiber through one of the first and second areas. Following transmission of the optical information through the multimode optical fiber, the optical information that is output from the other of the first and second areas is detected and decoded using the transfer function.

Abstract: A method includes generating a sequence of multiple optical pulses, for transmission into an optical fiber (12) having an array of multiple equally spaced reflectors (14) embedded therein, the sequence having a pulse duration and a pulse repetition interval (PRI) that guarantee that reflections of any of the optical pulses from any of the reflectors do not overlap. The sequence of optical pulses is transmitted into the optical fiber. The reflections of the optical pulses from the reflectors are extracted from the optical fiber. One or more events affecting the optical fiber are identified by analyzing the reflections.

Abstract: A system (10) includes an optical source, multiple coupler units (22), a controller (20), and a detector (123). The optical source is configured to transmit an optical signal into an optical cable (40). The multiple coupler units are coupled to the optical cable and are each configured to (i) accept one or more configuration parameters, (ii) receive data from one or more sensors (30), (iii) modulate the data onto an acoustical signal in accordance with the configuration parameters, and (iv) modulate a mechanical strain applied to the optical cable with the acoustic signal, so as to modulate the optical signal with the data. The controller is configured to coordinate and send the configuration parameters to the multiple coupler units. The detector is configured to receive the optical signal from the optical cable, and to demodulate the data that was modulated onto the optical signal by the multiple coupler units.

Abstract: An apparatus includes an electronic circuit, an electro-acoustic transducer and a coupler. The electronic circuit is configured to receive data to be transmitted over an optical cable, and to convert the data into a modulating signal. The electro-acoustic transducer is configured to convert the modulating signal into an acoustic wave. The coupler is configured to be mechanically coupled to a section of the optical cable, and to apply to the section a longitudinal stretching force that varies responsively to the acoustic wave, so as to modulate the data onto an optical carrier traversing the optical cable.

Abstract: An apparatus includes an electronic circuit, an electro-acoustic transducer and a coupler. The electronic circuit is configured to receive data to be transmitted over an optical cable, and to convert the data into a modulating signal. The electro-acoustic transducer is configured to convert the modulating signal into an acoustic wave. The coupler is configured to be mechanically coupled to a section of the optical cable, and to apply to the section a longitudinal stretching force that varies responsively to the acoustic wave, so as to modulate the data onto an optical carrier traversing the optical cable.

Abstract: An apparatus (32) includes an electronic circuit (76, 80, 84), an electro-acoustic transducer (60) and a coupler (64). The electronic circuit is configured to receive data to be transmitted over an optical cable (24), and to convert the data into a modulating signal. The electro-acoustic transducer is configured to convert the modulating signal into an acoustic wave. The coupler is mechanically coupled to a section of the optical cable, and is configured to apply to the section a longitudinal strain that varies responsively to the acoustic wave, so as to modulate the data onto an optical carrier traversing the optical cable.

Abstract: An apparatus (32) includes an electronic circuit (76, 80, 84), an electro-acoustic transducer (60) and a coupler (64). The electronic circuit is configured to receive data to be transmitted over an optical cable (24), and to convert the data into a modulating signal. The electro-acoustic transducer is configured to convert the modulating signal into an acoustic wave. The coupler is mechanically coupled to a section of the optical cable, and is configured to apply to the section a longitudinal strain that varies responsively to the acoustic wave, so as to modulate the data onto an optical carrier traversing the optical cable.

Abstract: A system (20) for fiber-optic reflectometry includes an optical source (28, 40), a beat detection module (44, 48, 52, 56A, 56B) and a processor (36). The optical source is configured to generate a non-linearly-scanning optical interrogation signal having an instantaneous optical frequency that is a non-linear function of time. The beat detection module is configured to transmit the optical interrogation signal into an optical fiber (24), to receive from the optical fiber an optical backscattering signal in response to the optical interrogation signal, and to mix the optical backscattering signal with a reference replica of the optical interrogation signal, so as to produce a beat signal.

Abstract: A system (20) for fiber-optic reflectometry includes an optical source (28, 40), a beat detection module (52, 56) and a processor (36). The optical source is configured to generate an optical interrogation signal that is transmitted into an optical fiber (24). The beat detection module is configured to receive from the optical fiber an optical backscattering signal in response to the optical interrogation signal, and to mix the optical backscattering signal with a reference replica of the optical interrogation signal using In-phase/Quadrature (I/Q) mixing, so as to produce a complex beat signal having In-phase (I) and Quadrature (Q) components. The processor is configured to sense one or more events affecting the optical fiber by analyzing the I and Q components of the complex beat signal.

Abstract: A system (20) for fiber-optic reflectometry includes an optical source (28, 40), a beat detection module (44, 48, 52, 56A, 56B) and a processor (36). The optical source is configured to generate a non-linearly-scanning optical interrogation signal having an instantaneous optical frequency that is a non-linear function of time. The beat detection module is configured to transmit the optical interrogation signal into an optical fiber (24), to receive from the optical fiber an optical backscattering signal in response to the optical interrogation signal, and to mix the optical backscattering signal with a reference replica of the optical interrogation signal, so as to produce a beat signal.

Abstract: Method for examining bone in vivo, comprises obtaining a laser beam; modulating the laser beam to insert therein photoacoustic frequencies including optical frequencies and acoustic frequencies, the acoustic frequencies being able to give rise to acoustic waves; directing the modulated beam at a bone to cause acoustic waves resulting from the beam to travel through the bone; analyzing received signals from the bone including signals resulting from the acoustic waves, to determine a mineral density and a bone quality for said bone, and thus obtain in-vivo data that can be of assistance to a doctor when diagnosing osteoporosis.

Abstract: A system (20) for fiber-optic reflectometry includes an optical source (28, 40), a beat detection module (52, 56) and a processor (36). The optical source is configured to generate an optical interrogation signal that is transmitted into an optical fiber (24). The beat detection module is configured to receive from the optical fiber an optical backscattering signal in response to the optical interrogation signal, and to mix the optical backscattering signal with a reference replica of the optical interrogation signal using In-phase/Quadrature (I/Q) mixing, so as to produce a complex beat signal having In-phase (I) and Quadrature (Q) components. The processor is configured to sense one or more events affecting the optical fiber by analyzing the I and Q components of the complex beat signal.

Abstract: Method for examining bone in vivo, comprises obtaining a laser beam; modulating the laser beam to insert therein photoacoustic frequencies including optical frequencies and acoustic frequencies, the acoustic frequencies being able to give rise to acoustic waves; directing the modulated beam at a bone to cause acoustic waves resulting from the beam to travel through the bone; analyzing received signals from the bone including signals resulting from the acoustic waves, to determine a mineral density and a bone quality for said bone, and thus obtain in-vivo data that can be of assistance to a doctor when diagnosing osteoporosis.

Abstract: Asymmetric grating assisted couplers present unique problems if dispersion is to be reduced to levels at which high data rate signals can be transmitted. To overcome these problems, the method of the present invention includes precisely controlling and monitoring the cross-sectional geometry of the coupler during stretching and fusing. By monitoring states of polarization in lowest order modes as the coupler is formed, coupler fusion can be terminated when optimum form birefringence minimizing PMD is achieved. Dispersion is further minimized by impressing a saturated index of refraction grating with substantially flat add/drop characteristics in the coupler, and introducing a controlled amount of twist.

Abstract: Optical components, particularly microoptic glass components used in synthesizing birefringence in filter systems based on polarization interferometer techniques, are fabricated using systems and methods which provide accurate frequency periodicity measurements. These measurements are derived from differential delays induced by in-process glass elements between beam components in a polarization interferometer unit and from progressive wavelength scanning across a wavelength band of interest. The consequent sinusoidal output variation has peak to peak spacings which are measured to provide frequency periodicity values from which precise length corrections for the optical elements can be calculated.

Abstract: Optical components, particularly microoptic glass components used in synthesizing birefringence in filter systems based on polarization interferometer techniques, are fabricated using systems and methods which provide accurate frequency periodicity measurements. These measurements are derived from differential delays induced by in-process glass elements between beam components in a polarization interferometer unit and from progressive wavelength scanning across a wavelength band of interest. The consequent sinusoidal output variation has peak to peak spacings which are measured to provide frequency periodicity values from which precise length corrections for the optical elements can be calculated.

Abstract: Interleavers for optical systems, including multiplexers and demultiplexers, are based on the use of non-birefringent elements in combination with polarization beam splitter to provide differential retardation effects for generation of precise transmittance functions. The retardation elements, in one particular example, are non-birefringent glasses arranged in individually athermal stages but the optical beams propagated through them are maintained in selected polarization states in each stage. Between or within the stages the polarization vectors are varied to match phase to a selected standard, such as an ITU grid. Within the stages, selected beam angle adjustments are made to shape the output transmittance characteristic.