Abstract: An optical device including an optical amplifier to amplify optical signals received through an optical input, and to supply the amplified optical signals from an optical output, and an optical filter coupled to the optical amplifier. The optical filter changes the gain slope of the optical amplifier in response to a change in a single parameter of the optical filter. The single parameter may be a change in a central wavelength of the optical filter function. The optical filter preferably has a parabolic spectral function. The single parameter may be varied as a function of temperature such that the variable optical attenuator compensates for variations in the gain spectrum of the optical amplifier that occur as a function of operating temperature.

Abstract: A heating apparatus includes: (i) a laser providing at least one beam of light capable of heating a small area of an object; (ii) a laser driver adapted to adjust optical power of this beam of light; (iii) a photo-detector adapted to detect and measure thermal radiation from the small area; and (iv) a control loop operatively linked to the laser driver and the photo-detector, the control loop providing a signal to the laser driver to adjust optical power of the beam of light based on amount thermal radiation detected by the photo-detector. According to one embodiment of the present the laser is a CO2 laser and the small area is less than 0.25 mm in width. According to another embodiment it is a Nd: YAG laser.

Abstract: An optical amplifying unit includes an input for the input optical signals and an output for the output of the optical signals. A single-mode active fiber codoped with Er and Yb is optically connected to the input and the output and adapted to amplify the optical signals. A first pump source generates a first pump radiation including an excitation wavelength for Er, and a second pump source for generates a second pump radiation including an excitation wavelength for Yb. A first optical coupler optically couples the first pump radiation into the core of the active fiber in a co-propagating direction with respect to signal direction, and a second optical coupler optically couples the second pump radiation into the core of the active fiber in a counter-propagating direction with respect to signal direction.

Abstract: The invention relates to an athermal optical waveguide grating device. The optical waveguide grating device includes a fiber Bragg grating secured and bonded to a supporting substrate member with a low thermal expansion securing glass, such as a copper alumino silicate glass. The inventive devices and method of making the devices include the utilization of intermediate solid insert members between the fiber and a negative thermal expansion substrate.

Abstract: A UV light-curable composition comprises: (a) a first component, said first component being UV light-polymerizable polymer having a first index of refraction; and (b) a second component, the second component being UV light-polymerizable monomer having a second index of refraction, the second index of refraction being higher than said first index of refraction; wherein the first component polymerizes slower upon exposure to UV radiation than the second component.

Abstract: A method for writing a Bragg grating in a waveguide comprises the steps of placing the waveguide in a writing position in which the waveguide extends essentially along one axis; generating a beam of ultraviolet radiation; executing a first and a second scan with the said beam along the waveguide through a phase mask, in such a way as to generate interference fringes capable of modifying the refractive index along the said waveguide in a predetermined way; moving the phase mask, during the first or the second scan, with an oscillatory motion about one of its equilibrium positions and along a direction lying at an angle of less than 90° to the axis of the said waveguide, in such a way as to produce, in this scan, an essentially zero envelope of the refractive index; and varying the intensity of the energy of the ultraviolet radiation in a controlled way along the waveguide during the first and the second scan, for example by controlling the scanning velocity.

Abstract: An improved temperature-compensated optical grating device includes a temperature-compensating structure including a plurality of members that are selected and arranged to provide an effective coefficient of thermal expansion that is negative with respect to two mounting points for an optical fiber grating, wherein the improvement is achieved by making at least one of the members of the temperature-compensating structure from a material having a low coefficient of thermal expansion that decreases with increasing temperature and at least one other member having a high coefficient of thermal expansion that increases with increasing temperature.

Abstract: An optical amplifier site comprising: (i) a distributed Raman amplifier providing a first signal gain level; (ii) an optical amplifier located downstream from the distributed Raman amplifier, the optical amplifier being indirectly coupled to the distributed Raman amplifier, the optical amplifier including a first amplification medium, providing a second signal gain level; (iii) at least one optical signal loss element located between the distributed Raman amplifier and the optical amplifier and, contributing at least 0.5 dB optical loss to the amplifier site; (iv) a second amplification medium located down-stream from the first amplification medium; and (v) at least another one optical signal loss element, this at least another one optical signal loss element being located between said first amplification medium and said second amplification medium.

Abstract: An optical transmission system is provided comprising a thulium doped optical fiber, a light emitting pump device optically coupled to the thulium doped fiber, and a Raman amplifier fiber optically coupled to the thulium doped optical fiber. The light emitting pump device in combination with the thulium doped fiber generates a first amplification pump wavelength and the Raman amplifier receives the first amplification pump wavelength. The first pump wavelength amplifies an optical signal in the Raman amplifier, the Raman amplifier operating at a signal wavelength in the range of about 1530 nm to about 1625 nm.

Abstract: An optical amplifying unit (100; 100′) for amplifying optical signals in an optical transmission system has an amplification wavelength band with a lower wavelength limit greater than 1570 nm and includes an input (101) for the input of optical signals, an output (102) for the output of optical signals and an optical amplifier (104) interposed between the input (101) and the output (102) to amplify the optical signals. The optical amplifier (104) includes an amplification fiber (108) co-doped with erbium and ytterbium, at least a pump source (109, 110) to generate pump radiation and at least an optical coupler (111, 112) optically coupling the pump sources (109, 110) to the amplification fiber (108). The optical amplifying unit has a power gain of at least 31 dB when the optical signals have an input power of at least −10.5 dBm and wavelengths within the amplification wavelength band.

Abstract: A length of oxynitride optical fiber is exposed to actinic radiation that is modulated by an interference technique to form a pattern of refractive index variations that functions as a reflective grating.

Abstract: A method for tuning and improving the performance of an optical communication system comprising al link that includes optical amplifiers and, optionally, active and/or passive optical components such as, e.g., DWDM's, WADM's, and optical cross-connects, includes preferentially shaping and, in particular, flattening, with respect to the input power spectrum, the output power spectrum from the amplifier, component or of the link. A flattened output power spectrum is obtained by modifying the gain spectrum operating on the respective input power spectrum. Feedback for such gain modification is typically provided by optimizing the optical signal to noise ratio of each channel of the respective output power spectrum. A system link, an optical amplifier, and optical components having flattened output power spectra are also described.

Abstract: One aspect of the invention is an optical add/drop multiplexer. The optical add/drop multiplexer includes a first optical circulator, the first circulator includes a first port, a second port, and a third port. The optical add/drop multiplexer also includes a first tunable grating coupled to the first port and a second tunable grating coupled to the first grating. The optical add/drop multiplexer further includes a second optical circulator, the second optical circulator includes a fourth port, coupled to the second grating; a fifth port, and a sixth port. Wherein the first tunable grating is a fiber Bragg grating and wherein the second tunable grating is a fiber Bragg grating.

Abstract: A method for upgrading bandwidth in a fiber optic system utilizing Raman amplification and having an initial band capacity provided by a plurality of pumps including the steps of identifying a fiber optic system to be upgraded, activating at least one new pump in the fiber optic system necessary to provide upgraded band capacity to the fiber optic system while retaining the initial band capacity provided by the plurality of pumps, and adjusting power of at least one pump of the fiber optic system to minimize gain ripple or signal output ripple.

Abstract: Suppression of stimulated Brillouin scattering (SBS) by broadening the energy spectrum of participating SBS photons and/or phonons is achieved in an optical fiber having a core with both radially nonuniform viscosity and CTE profiles provided by alternating layers of glass modifying dopants such as phosphorous and fluorine. The nonuniform thermal expansion and viscosity profiles impart a residual, permanent, nonuniform stress in the fiber. The SBS suppressing effect provided by the nonuniform stress can be controlled and enhanced by applying a uniform or nonuniform tensile force to the fiber as it is being drawn. A preform for the fiber is also disclosed.

Abstract: A dynamic controller for a multi-channel EDFA-type optical amplifier is provided that is capable of providing a substantially tilt-free output over a range of selectable gain set points. The dynamic controller includes a variable optical attenuator coupled between the two amplification coils of the EDFA amplifier, and a control circuit that instructs the attenuator of an amount that each channel should be attenuated to achieve a tilt-free output at a selected gain point. The controller further includes a gain controller and a tilt controller connected to the control circuit of the variable optical attenuator for providing signals indicative of an average amount of per channel attenuation and a relative amount of per channel attenuation necessary to achieve a selected gain set point while reducing or eliminating tilt, respectively.

Abstract: An optical fiber amplifier includes an optical system and an electronic controller. The optical system includes: an optical gain medium; at least one pump source coupled to the optical gain medium; an input port for in-coming signal; and an output port for an out-going signal. It also includes an input optical signal tap coupled to a first optical detector; and an output optical signal tap coupled to a second optical detector. The electronic controller is adapted to utilize inputs received from the tabs to control optical power provided by the pump source. The controller includes a user interface that allows a user to control at least one of the following available functions: desired amplifier gain value; amplifier output power value; ASE noise compensation.

Abstract: A method of operating a noise compensating gain controller in an optical amplifier to avoid overshoot of a selected gain level during amplification transients is provided. The first step of the method includes the computation of a difference in the amount of amplification necessary to bring the combination of the signal and noise component forming the optical output to the selected gain level. Next, a computation is made of an adjustment of the amplification difference that is necessary to bring the signal component of the output to the selected gain level at a post-transient, steady-state condition of the optical input. In the final step, the amplification is changed in accordance with the computed difference in the amount of amplification either prior to or simultaneously with the adjustment to this difference.

Abstract: A method for amplifying optical signals and an optical fiber amplifier for accomplishing the same. An optical fiber is coupled to a source of pump light and a signal gain level is correlated to a dispersion value of the optical fiber that corresponds to a local minimum power level of a cross-talk signal generated by four wave mixing. Optical signals are transmitted through the optical fiber while admitting sufficient pump light into the fiber from the source to attain the selected Raman gain level.

Abstract: An optical transmission system includes an optical transmitting unit (10) to transmit optical signals in a transmission wavelength band above 1570 nm; an optical receiving unit to receive the optical signals; an optical fiber link optically coupling the transmitting unit to the receiving unit, at least an optical amplifying unit (100) coupled along the link and adapted to amplify the optical signals; the optical amplifying unit (100) having an amplification wavelength band including the transmission wavelength band and comprising: an input (101) for the input of the optical signals, an output (102) for the output of the optical signals, at least an erbium-doped active fiber (103a, 103b) for the amplification of the optical signals, having a first end optically coupled to the input (101) and a second end optically coupled to the output (102), a pump source (104, 106) for generating a pump radiation having a wavelength greater than 1400 nm and lower than 1470 nm, and an optical coupler (105, 107) optically coup