Abstract: A wavelength tunable mode-locked laser system including a complex laser cavity comprising a broadband reflective mirror at one end and a wavelength chirped selective mirror at the other end. The system further includes a gain element and a low finesse Fabry-Perot etalon element inside the laser cavity. The gain element may be a semiconductor laser chip, with a broadband high reflection coating at one end and a partially reflecting coating at its other end. The gain element has a well-defined length, such that its longitudinal modes match a required optical frequency grid. The system also includes an active modulation element applied externally on said complex laser cavity to provide mode-locking of a specific cavity length among said defined predetermined cavity lengths, such that all possible optical frequencies emitted by the laser system are stabilized to the linear grid dictated by the Fabry-Perot longitudinal modes, that could be in accordance with the International Telecommunications Union Standards.

Abstract: A wavelength tunable mode-locked laser system including a complex laser cavity comprising a broadband reflective mirror at one end and a wavelength chirped selective mirror at the other end. The system further includes a gain element and a low finesse Fabry-Perot etalon element inside the laser cavity. The gain element may be a semiconductor laser chip, with a broadband high reflection coating at one end and a partially reflecting coating at its other end. The gain element has a well-defined length, such that its longitudinal modes match a required optical frequency grid. The system also includes an active modulation element applied externally on said complex laser cavity to provide mode-locking of a specific cavity length among said defined predetermined cavity lengths, such that all possible optical frequencies emitted by the laser system are stabilized to the linear grid dictated by the Fabry-Perot longitudinal modes, that could be in accordance with the International Telecommunications Union standards.

Abstract: An all-fiber, optically-tunable, narrowband optical loop-mirror filter (10) that makes use of a loop-mirror (24). The optical filter (10) includes a coupler (12), including two input fiber ports (14, 16) and two output fiber ports (18, 20) that are connected together to form the loop-mirror (24). A saturable medium (22) is positioned in the loop-mirror (24), and can be either a saturable absorber medium or a saturable gain medium. A potentially broadband optical input signal to be filtered and a pump are applied to the input ports (14, 16) of the coupler (12). The counter propagating signals in the loop-mirror (24) generated by the input signal and the pump create two standing wave interference patterns in the saturable medium (22). Depending on whether the input signal and the pump are applied to the same input port (14, 16) or different input ports (14, 16) determines whether the two standing wave interference patterns are in phase with each other or &Xgr; radians out of phase with each other.

Abstract: A wavelength-selectable laser system (10) is achieved by addressing the suitable mode-locked frequency of a multi-length laser cavity formed by multiple wavelength-selective mirrors (20) such as fiber gratings. This is useful for fiber optic communication and WDM (wavelength division multiplexing) networks where there is incorporated an information encoder/modulator (22) of the light in the sending side and a detector in the receiving side, which are matched to the laser system.

Abstract: A method and apparatus for fixing images, holograms and domain gratings in crystals by application of an electric field on a crystal and simultaneous illumination of it with a light pattern. The fixing procedure is based on a screening effect. The modulation of the domains may be perpendicular to the c-axis. Another application of the method is in frequency mixing such as second harmonic generation and parametric processes, by overcoming the problem of phase matching using the domain gratings. Thus, it is possible to obtain controllable broadband mixing and tailored quasi-phase matching for several wavelengths or for prespecified wavelength tuning ranges and frequency widths.

Abstract: A method of using a distributed saturable absorber added to a laser cavity, which by nonlinear wave-mixing of the counterpropagating beams (or spatial hole-burning) promotes a reduction of the linewidth and a single mode operation.

Abstract: A novel optical system and method for coupling and mixing a plurality of beams which may originate from different optical sources and may be of different colors. There is provided deflection and steering of light beams with automatic (self-aligning) Bragg matching over a large beam deflection range which is not limited by the Brass condition. There is also provided a novel method of spatial light filtering and modulation, image color conversion, bidirectional beam interconnection for optical communication and combining and locking of laser sources.

Abstract: Optical apparatus, particularly useful as an optical gyro for measuring rotation, comprises a light source, an optical system defining a closed-loop optical path, an optical-wave-mixer producing form the light source beam an oscillating beam in the closed-loop optical path, and a circuit for measuring the phase or frequency shift produced in the oscillating beam by the optical-wave-mixer resulting from the non-reciprocal or reciprocal phase-shift thereof. A mathematical analysis is set forth showing how the non-reciprocal phase-shift is related to the frequency shift, so that the frequency shift provides a measurement of the non-reciprocal phase-shift, which depends on the rotation of the closed-loop ring optical path, thereby enabling the apparatus to serve as an optical gyro.

Abstract: A passive (self-pumped) phase conjugate mirror uses a third-order nonlinear polarization medium, either of the refractive type (effective nonlinear) or the actual nonlinear type, with an optical system of one or more mirrors to reflect back through the medium a coherent incident beam diffracted by the medium. With two mirrors, they may be aligned to form a linear optical cavity containing the nonlinear medium, or they may be so oriented on one side of the medium that the incident beam transmitted through the medium is reflected back through the medium at an angle with the incident beam, and diffracted light from the incident beam is reflected back through the medium in the opposite direction coincident with the incident beam. A passive phase conjugate mirror may replace an end mirror of an optical cavity for a laser gain medium. Phase distortions of the laser beam in the laser cavity are corrected by the passive phase conjugate mirror.