Lumonics Inc.

Nortel Networks Corporation

Jds Uniphase Corporation

Lumentum Operations LLC

Gsi Lumonics Corporation

David R Walker

Barthelemy Fondeur

Jinxi Shen

Leonid Frenkel

Yimin Hua

Vlatko Milinkovic

Yu Zhang

Michael Armstrong

John Reid

Robert John Dwayne Miller

Philip D Barton

Robert G Parker

Robert K Brimacombe

Yan Liao

A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The cascade of MZ interferometers, each having a free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. Another MZ interferometer in series with the cascade of interferometers including an asymmetric or variable coupler, is tuned to have low transmission at the center frequency of the selected optical channel.

Flat-top tunable filter

A tunable optical filter is configured to take point measurements at a few optical frequencies per frequency channel of a DWDM optical network. The measurement frequencies are shifted by pre-determined amounts relative to the optical frequency channel being characterized. Since the spectral shape of the tunable optical filter is known, the center optical frequency, the modulation bandwidth, and the total optical power of the channel can be obtained from as few as three optical measurements. The center optical frequency and the total optical power can be continuously monitored by providing a tunable filter stage coupled to an interleaver stage, and computing a ratio and a weighted sum the optical signals at the two outputs of the interleaver stage.

Characterizing a frequency channel in an optical network

The effects of dispersion of light on a link having an optical transmission fibre characterised by positive dispersion and large positive relative dispersion slope can be reduced by employing a sufficient length of dispersion compensating fibre (&ldquo;DCF&rdquo;) so that dispersion slope on the link is substantially nulled and the net dispersion of the link is made negative. Optical signals launched on the link with a positive chirp will be compensated for by the net negative dispersion.

Reduction of dispersion effects in optical transmission fibre systems

A laser clamping system for a disc laser medium that includes two heat conductive members (one of which is optically transparent) positioned on either side of a disc laser. Pressure is applied to the conductive members to restrain the disc from deforming under pumping conditions to reduce the lensing effect. Thin disc geometry allows the thermal load of laser material to be much closer to the heat conductive members so that heat dissipation is generally more efficient than that of other geometric configurations (e.g. rod or slab). In disc lasers each part of the laser beam experiences the same temperature gradient so that there is no lensing effect caused by radial temperature distribution. It has been discovered that any resulting lensing effect is disc lasers is mainly from the thermo-mechanical deformation of the disc itself. Consequently, a disc laser with clamped boundary conditions using the system as described above reduces the lensing effect and enables scaling laser power to a much higher level compared to unclamped disc laser systems. The clamping system and method of the present invention also improves performance in rod and slab type laser medium geometries.

Laser clamping assembly and method

A laser machining (including marking) method that employs a diode laser pumped solid state laser is controlled by a computer that contains a program for the interaction of the laser beam with a workpiece. The pumping of the laser is synchronised with the action of the beam in a series of active machining periods alternating with inactive non-machining periods. In order to avoid overheating of the active element, the duty cycle of these periods is maintained below a chosen value and no active period is allowed to exceed a selected percentage of the thermal time constant of the active element.

Laser machining of a workpiece

The energy of a series of output pulses of a solid state laser pumped by a diode array and triggered by a Q-switch is stabilized and rendered independent of the repetition rate by interrupting the pumping to allow the energy stored in the laser active element to fall at the commencement of an interval between a pair of Q-switch trigger signals that is longer than the interval corresponding to the chosen repetition rate. Before the second of this pair of Q-switch trigger signals occurs, the pumping is recommenced for a duration and at an input level that restore the stored energy to the value required for generating output pulses of the laser at the desired energy level.

Stabilization of the output energy of a pulsed solid state laser

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Ottawa, Canada

David R Walker