Abstract: In-line optical polarimeters and techniques for calibrating such polarimeters are described. In one implementation a polarimeter integrates components in free space to enhance device performance.

Abstract: A system for filtering light propagating in a waveguide is described. The system utilizes an adjustable periodic grating which induces mode coupling of predetermined frequencies of light propagating in the waveguide.

Abstract: A system for filtering light propagating in a waveguide is described. The system utilizes an adjustable periodic grating which induces mode coupling of predetermined frequencies of light propagating in the waveguide.

Abstract: Optical frequency-division filters for multiplexing and demultiplexing operations by combining wavelength-selective filtering and polarization properties of optical signals.

Abstract: Techniques and systems for monitoring a difference between the frequency of a laser and a resonance of a birefringent optical resonator. A feedback control loop may be used to lock the laser to the resonator, or alternatively, to lock the optical resonator to the laser.

Abstract: A system for filtering light propagating in a waveguide is described. The system utilizes an adjustable periodic grating which induces mode coupling of predetermined frequencies of light propagating in the waveguide.

Abstract: Systems and techniques of incorporating an optical resonator in an optical part of a feedback loop in opto-electronic oscillators. This optical resonator provides a sufficiently long energy storage time and hence to produce an oscillation of a narrow linewidth and low phase noise. Certain mode matching conditions are required. For example, the mode spacing of the optical resonator is equal to one mode spacing, or a multiplicity of the mode spacing, of an opto-electronic feedback loop that receives a modulated optical signal and to produce an electrical oscillating signal.

Abstract: Techniques and devices for depolaring polarized light by using one or more birefringent optical elements in the optical path of light to scramble the state of polarization of light. Examples of devices for coupling with a fiber or a fiber device, and their applications in various fiber environments are also described.

Abstract: Systems and techniques of incorporating an optical resonator in an optical part of a feedback loop in opto-electronic oscillators. This optical resonator provides a sufficiently long energy storage time and hence to produce an oscillation of a narrow linewidth and low phase noise. Certain mode matching conditions are required. For example, the mode spacing of the optical resonator is equal to one mode spacing, or a multiplicity of the mode spacing, of an opto-electronic feedback loop that receives a modulated optical signal and to produce an electrical oscillating signal.

Abstract: Depolarizing system for polarized light formed of a birefringence crystal wedge which receives the beam of polarized light at a first surface and outputs spatially depolarized light from its output surface. The wedge may include small steps on one of the surfaces or special orientations to depolarize the light. The wedge may be substantially triangular in shape so that the surface decreases from one side to the other.

Abstract: An improved polarization control method and apparatus is provided. The described invention uses super-polished squeezing surfaces to apply pressure against a polyimide coated fiber thereby minimizing micro-bending effects that cause losses in the fiber. Special control circuitry has also been designed to maintain a driving source of piezo-electrics that control the squeezing surfaces at a resonant frequency, thereby minimizing the voltages needed to drive the piezo-electrics.

Abstract: Devices that couple variable attenuators to a single WDM multiplexer to individually adjust and control the power levels of different WDM channels, e.g., substantially equalizing the power levels of the channels. Optical reflection and in-fiber variable attenuators are implemented to simplify the device structure and reduce cost.

Abstract: An improved polarization control method and apparatus is provided. The described invention uses super-polished squeezing surfaces to apply pressure thereby minimizing micro-bending effects that cause losses in the fiber. Special control circuitry has also been designed to maintain a driving source of piezo-electrics that control the squeezing surfaces at a resonant frequency, thereby minimizing the voltages needed to drive the piezo-electrics.

Abstract: Systems and techniques for transmitting and processing an electrical signal through an opto-electronic system with an optical Brillouin amplifier.

Abstract: A wavelength converter including a chip having formed therein a first electro-absorption modulator biased as a photodetector, and a second electro-absorption modulator biased as a modulator electrically coupled to the first electro-absorption modulator. The first electro-absorption modulator detects an input signal at wavelength &lgr;1 and generates an electrical signal to control the second electro-absorption modulator's modulation of light from a wave source at wavelength &lgr;2.

Abstract: A linear swept frequency generator includes a signal generator that generates an output signal having a frequency that varies between a first frequency and a second frequency. A delay element, such as an optical fiber having a reflector at one end, is configured to receive the output signal and to produce a delayed version of the output signal. This delayed version of the output signal is provided, along with the output signal, to a mixer that combines the signals to produce a reference signal. Finally, a feedback path between the mixer and the signal generator provides the reference signal to the signal generator so that the signal generator controls the frequency of the output signal in response to the reference signal.

Abstract: An electro-optical oscillator includes an electro-optical modulator having an electrical input port that accepts an electrical control signal and an optical output port. The electro-optical modulator is operable to generate at the optical output port an optical signal that oscillates at a frequency related to the electrical control signal. The oscillator also includes a photodetector that converts a portion of the optical signal from the optical output port of the electro-optical modulator to an electrical signal and provides the electrical signal to the electrical input port of the electro-optical modulator as the electrical control signal. An open loop gain of a feedback loop including the optical output port, the photodetector and the electrical input port is greater than one.

Abstract: A polarization insensitive electro-optic modulator is constructed by providing a polarization beamsplitter to separate an incoming light beam into two orthogonally plane polarized beams. Each of the polarized beams passes through a separate electro-optic modulator where each beam is modulated by the same data signal. After modulation the beams are combined to yield a modulated beam having modulated components that are orthogonally polarized. Not only is this device insensitive to changes in polarization of the input beam, the final modulated beam can be detected by optical receivers without regard to polarization alignment of the modulated beam and the receiver.