Abstract: A micro-electro-mechanical (MEMs) mirror device for use in an optical switch is disclosed. A “piano”-style MEMs device includes an elongated platform pivotally mounted proximate the middle thereof by a torsional hinge. The middle portion of the platform and the torsional hinge have a combined width less than the width of the rest of the platform, whereby several of these “piano” MEMs devices can be positioned adjacent each other pivotally mounted about the same axis with only a relatively small air gap therebetween. In a preferred embodiment of the present invention specially designed for wavelength switching applications, a greater range of arcuate motion for a mirror mounted thereon is provided by enabling the platform to rotate about two perpendicular axes.

Abstract: The invention provides a hermetic seal and a method of making a hermetic seal having the steps of providing a first member of a first material having a flange thereon, providing a second member of a second material having a slot thereon for accommodating the flange in said slot such that there is a gap between the slot and the flange, providing a sealant in the slot, and heating the sealant such that the sealant fills at least a portion of the gap between the flange and the slot for forming a hermetic seal therebetween. Advantageously, the slot and flange design of the inventive hermetic seal produces a three-dimensional compressive state of stress thereby providing a joint design of improved reliability.

Abstract: The invention relates to an optical circulator for use as a front end for an optical device platform, which requires a pair of like-polarized sub-beams as input. A combined beam of light comprising a plurality of wavelength channels is input the optical circulator at an input port, and the pair of like-polarized sub-beams is launched via a pair of input/output ports into the optical device platform, wherein the sub-beams are modified. Within the optical device platform the combined beam of light is separated into individual channels, and one or more of the channels can be dropped or attenuated before the remaining channels are recombined into to modified sub-beams for output. The two modified sub-beams are launched back into the optical circulator, which directs the modified sub-beams to an output port remote from the input port. Any light reentering the optical circulator with the wrong polarization will neither exit the input nor the output port.

Abstract: A system for determining response characteristics, insertion loss and group delay, of an optical component by applying a sweeping wavelength optical signal that is modulated with an RF signal, measuring the insertion loss and group delay at a series of wavelengths and correlating the measurements to wavelengths. A method for synthesis of an effective modulation frequency in determining the group delay response characteristics of an optical component by obtaining a series of measurements over a sample optical spectrum using a given modulation frequency and calculating a weighted average of the group delays in the series of measurements giving a result substantially equivalent to a measurement taken using a modulation frequency equal to the effective modulation frequency.

Abstract: A micro-electro-mechanical (MEMs) mirror device for use in an optical switch is disclosed. A “piano”-style MEMs device includes an elongated platform pivotally mounted proximate the middle thereof by a torsional hinge. The middle portion of the platform and the torsional hinge have a combined width less than the width of the rest of the platform, whereby several of these “piano” MEMs devices can be positioned adjacent each other pivotally mounted about the same axis with only a relatively small air gap therebetween. In a preferred embodiment of the present invention specially designed for wavelength switching applications, a greater range of arcuate motion for a mirror mounted thereon is provided by enabling the platform to rotate about two perpendicular axes.

Abstract: This invention relates to a new optical geometry for using a linear variable filter as an optical spectral filter. An elliptical beam geometry with the minor beam axis oriented along the linearly varying axis of the filter is used. The beam is incident at a slight angle relative to the long axis of the beam. Ultimately this geometry produces a filter which has minimum spectral broadening from both angular and beam extent effects. Furthermore, this geometry results in low back reflectance and higher input beam power damage thresholds. The optical filter includes means for tuning a wavelength response of the filter. Further, the optical filter can afford Add/Drop functionality by providing optical circulators at the input and output ports.

Abstract: A polarization controller comprising means for generating linearly polarized light and at least one liquid crystal cell. A preferred embodiment of the invention comprises a linear polarizer and two liquid crystal cells. In the preferred embodiment, the polarization direction of the polarizer and the orientation of the fast axis of the first and second liquid crystal cells are oriented in a manner that allows the linearly polarized light provided by the polarizer to be transformed into any state of polarization at the output of the second liquid crystal cell. The present invention provides full coverage of the Poincaré sphere.

Abstract: Small mechanical devices fabricated from semiconductor substrates called micro-electromechanical systems (MEMS) are used in the telecommunications industry for various purposes, such as switching and attenuation. Typically a small mirror or arm is moved into or out of the optical path of a beam of light to redirect of attenuate the signal. The present invention relates to a drive circuit for a MEMS device that converts a low voltage source into a higher more useful voltage pulse. The present invention also relates to an optically powered MEMS device utilizing the aforementioned drive circuit. Moreover, the drive circuit according to the present invention can be used to generate a single exponentially decaying pulse that can both generate an actuation force and a braking force for the MEMS device.

Abstract: The invention provides a variable optical attenuator or array with low PDL by using an embedded polymer channel waveguide with a plurality of resistive heaters fabricated on the top cladding of the polymer waveguide. The resistive heaters create a strong thermal gradient in the polymer layer stack which is associated with a strong refractive index gradient with the lowest refractive index under the heater. This refractive index gradient causes the optical mode in the channel to shift towards the buffer layer. Attenuation is induced by transition losses between heated and unheated regions in the polymer waveguide when an optical signal passes through these regions of the polymer waveguide.

Abstract: A method and device is disclosed for relaying a narrow diameter collimated optical beam carrying optical communication signal channels between a multilayer interference filters and another reflective surface avoiding signal loss by routing the optical beam to compensate for beam broadening caused by the multilayer interference filter. The method and device are particularly applicable to dispersion compensating filters, especially those wherein one filter is tunable, in that a controllable amount of dispersion is introduced to offset or compensate dispersion. Preferably one of the filters is a tunable periodic device in the form of a multi-cavity etalon structure. In a preferred embodiment of the filters can be designed to provide various controllable but different constant amounts of dispersion.

Abstract: The invention relates to an optical coupling device that provides passive compensation for a shift in center wavelength due to a change in ambient temperature. A conventional solution is to mount one of the elements to be coupled on a pedestal or cantilevered arm, which has a coefficient of thermal expansion (CTE) different from a frame fixed relative to the other of the elements to be coupled. Unfortunately, these devices do not provide consistent results over long periods of time, due to uncontrolled movement of the outer free end of the cantilevered arm or pedestal. The present invention provides an expansion arm fixed on one end to a frame, a holder on the other end of the expansion arm, and a pair of flexible arms connecting the holder to the frame. This arrangement enables the expansion arm to freely expand in a first direction, while greatly restricting movement in any other direction.

Abstract: An optical device for rerouting and modifying an optical signal that uses a double pass through a liquid crystal modulator is disclosed. The optical device includes a first polarizer for providing polarized light, a liquid crystal modulator for selectively modifying the polarized light, a second polarizer for analyzing the light passed through the liquid crystal modulator, and a reflector for reflecting the analyzed light back through the second polarizer, the liquid crystal modulator, and the first polarizer. This arrangement provides a double pass through the liquid crystal modulator, thus significantly improving the attainable extinction ratio.

Abstract: A tunable PM fiber combiner is configured to be accurately alignable with and operative to combine into a single composite beam a pair of non-collimated, orthogonally polarized light beams transported over polarization maintaining (PM) optical fibers, whose mutual spatial separation may vary. The combiner includes birefringent elements, that are linearly or rotationally displaced to realize the composite beam. The resulting composite light beam may then be readily coupled (e.g. via a single mode fiber) to a downstream beam processing device, such as a Raman amplifier.

Abstract: A modular optical platform for selective wavelength switching that can be adapted to perform various other functions, such as dynamic gain equalization (DGE) and add/drop multiplexing (ADM) provides the versatility and modularity that will be essential to the future of the fiber optics industry. The basic platform includes a first lens for directing an optical signal, a diffraction grating for dispersing an optical signal into its component wavelength channels, a second lens for directing the component wavelength channels, and a modifying device for conducting one or more of a variety of functions including switching, DGE and ADM. The first and second lens are preferably replaced by a single concave reflective mirror having optical power.

Abstract: A dispersion compensator has a linearly chirped fiber Bragg grating mounted at two ends of an elongated, channel-shaped heat distributor. The distributor has two thermo-electric coolers at two ends, a heating strip for uniform heating of the distributor, a temperature sensor mounted on the distributor in the middle of the grating region, and longitudinally variable heating means attached to the distributor and extending along its length for effecting a longitudinally varying heating of the grating region. The provision of the heating strip helps maintain linearity of the thermal gradient of the distributor while the longitudinally variable heaters facilitate relatively fast dithering of the temperature of the grating region.

Abstract: The invention provides an optical device including a polarization diversity unit for receiving an input optical signal and producing two beams of light having a same polarization state therefrom, a beam swapping element disposed for receiving the first and second beams of light and for redirecting the two beams of light to a same overlapping area of a modulator, and a reflective surface for reflecting the two beams of light back to the polarization diversity unit where they are combined to form an output optical signal. The beam swapping element is designed and positioned such that the first and second beams of light swap positions upon reflection from the reflective surface and trace out the other's optical path. Advantageously, this optical arrangement essentially eliminates all PDL and PMD.

Abstract: A method and device is disclosed for dispersion compensation of an optical signal having periodic dispersion within a multi-channels system. For example interleaved optical channels often exhibit dispersion having a characteristic that is repeated in adjacent channels. By providing a periodic device that allows for polarization dependent routing of an interleaved signal to allow for multiple passes of said signal through a multi-cavity GT etalon, having a free-spectral range that corresponds to the channel spacing, the dispersion in the interleaved signal can be lessened and practically obviated or balanced to a desired level. This invention provides a device and method to achieve that end.

Abstract: An apparatus for measuring chromatic dispersion in a waveguide uses a probe signal and a modulated pump signal which are coupled together into a waveguide. The modulated pump signal causes spatial and temporal Raman gain modulation of the probe signal. The amplitude of the pump signal is modulated and the frequency response of the probe signal at the output end of the waveguide is measured. The chromatic dispersion of the waveguide at a given wavelength is determined from the measurements. The probe signal is provided by a CW laser or corresponds to the ASE generated by the pump signal.

Abstract: The present invention relates to an optical filter comprising an integrated wavelength dispersive element having an input for providing temperature compensation, particularly for providing passive temperature compensation in an arrayed waveguide grating. The present invention has found that by providing an arrayed waveguide grating having a thermally responsive pivotal input structure for changing an angle of a collimated input signal launched into a focusing lens, the input point can be selected in response to changing temperature in order to compensate for thermal drift of the center wavelength. Further, the present invention has found that by providing a reflective lens assembly for focusing an input signal at a selected input point of the input planar waveguide, alignment and tuning of an input and assembly can be improved and simplified.

Abstract: A method for solder bonding a photodiode or an array of photodiodes to a substrate, the photodiode(s) tilted at a predetermined angle, uses a pair solder bumps placed on a photodiode chip opposite a corresponding pair of solder pads placed on the substrate. When the photodiode chip is placed on the substrate, with the solder bumps therebetween, the solder is melted and undergoes a reflow over the surface of the pads. The shape of the pads and the location of the solder bumps on the pads causes the surface tension of the solder to tilt the chip by pulling it to one side.