Abstract: A system and method for real time process control, using a linearly swept tunable laser, which allows high speed in-situ monitoring and control of wavelength-specific properties of optical components. The invention comprises scanning an optical component with a high speed, high linearity tunable laser, and detecting optical output from the component during the scanning. Preferably, the invention also includes adjusting or controlling the optical properties of the component during scanning, according to detected optical output from the component. The invention is embodied in a process control system comprising a high speed, high linearity, tunable operatively coupled to an optical component which in turn is operatively coupled to an optical detector. A system control processor is operatively coupled to the tunable laser and detector. A processing control unit is associated with the optical component and is operatively coupled to the system control processor.

Abstract: A method and apparatus for minimizing the effects of noise when measuring a response of a device under test to laser light. Laser light provided from a laser source is provided to an interferometer, which splits the source laser light into a first laser light portion and a second laser light portion and then interferometrically combines the first laser light and the second laser light, resulting in a time-varying interference modulated test laser light and a time-varying interference modulated reference laser light. The time-varying interference modulated test laser light is propagated to a device under test so as to cause the device under test to propagate responsive time-varying interference modulated test laser light. The responsive time-varying interference modulated test laser light is converted to an responsive amplitude modulated electrical test signal, which is high pass filtered.

Abstract: The present invention provides a velocity matched distributed photodetector/modulator (VMDP) for converting between an optical signal and an electrical signal. The converter has twice the theoretical efficiency of any prior art device. The converter wave-guide core is of uniform cross-sectional thickness and composition along the optical path, which makes it easy to fabricate. The converter includes a passive optical waveguide and a plurality of photodiodes. The photodiodes optically couple in series with the passive optical waveguide and electrically couple in parallel with one another to convey the electrical signal there between. The photodiodes exhibit impedance mismatches that generate reflections of the electrical signal, which contribute to a cancellation of reverse traveling portions of the electrical signal.

Abstract: The present invention provides a continuously tunable external cavity laser (ECL) with a compact form factor and precise tuning to a selected center wavelength of a selected wavelength grid. The ECL may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid. The ECL does not require a closed loop feedback. A novel tuning mechanism is disclosed which provides for electrical or mechanical tuning to a known position or electrical parameter, e.g., voltage, current or capacitance, with the required precision in the selected center wavelength arising as a result of a novel arrangement of a grid generator and a channel selector. The grid generator exhibits first pass bands which correspond to the spacing between individual channels of the selected wavelength grid and a finesse which suppresses side band modes of the laser. The channel selector exhibits second pass bands that are wider than the first pass bands.

Abstract: Described embodiments provide a method and apparatus for transmission of optical communications. An embodiment provides an optical transmitter which includes a control circuit to enhance the stability of output power levels, a modulator circuit with precise impedance matching for high frequency performance, and an optical coupling mechanism that relaxes the alignment tolerances between the laser and the fiber and decreases the sensitivity of the gain medium to feedback from devices coupled to the fiber. These features allow the transmitter to deliver an optical output beam which can be modulated over a wide range of frequencies, duty cycles and amplitudes with very precise definition of the rising and falling edges of the waveform. In combination these features result in an optical transmitter that may be fabricated with relatively low cost and a reduced form factor when compared with prior art optical transmitters.

Abstract: The present invention provides an apparatus for passively stabilizing the optical pathlength in tunable lasers. Lasers stabilized using the passive stabilization apparatus exhibit reduced mode hop and increased wavelength stability during temperature variations of the laser or surrounding environment. The stabilization makes the laser suitable for a broad range of applications including: optical signal generators and optical multimeters.

Abstract: A method and apparatus for controlling a piezo-electric actuator coupled to a driven member is disclosed. The piezo-electric actuator is responsive to waveforms with asymmetrical voltage/current profiles on the rising and falling edge to effect consistent and cumulative movement of the driven member in one of two directions throughout the reciprocations of the piezo-electric actuator. The waveforms are digitally generated from a stored set of numbers or a function for generating the set of numbers. The numbers correspond with the discrete digital values associated with the desired waveforms for moving the driven member in either of at least two directions. The controller may be used to drive more than one piezo-electric actuator. The controller may include responsiveness to a feedback of the position of the driven member to accurately position the driven member.

Abstract: Apparatus and associated method for aligning optical components including lenses, filters, lasers, fiber optics, etc. The apparatus aligns a first optic element and a second optic element and includes a frame and a sleeve. The frame defines a frame bore along a longitudinal axis thereof. The sleeve defines an eccentric bore configured to contain the first optic element or the second optic element. The sleeve is rotatably coupled in the frame bore to align the first optic element with the second optic element in a plane intersected by the longitudinal axis.

Abstract: The present invention provides an optical multimeter for use in calibrating and testing optical components. The optical multimeter includes an optical analog/digital signal generator for delivering an output beam over a wide range of frequencies, duty cycles and amplitudes. The optical signal generator includes a tunable laser. The tunable laser exhibits a small form factor, due in part to a novel wavelength control process which utilizes an open loop system to maintain precise output wavelength control, without the requirement of either a wavelength or position feedback device.

Abstract: An optical isolator includes a first stage configured to refract a light ray applied in a forward direction into a first ray and a second ray. A second stage rotated 90° with respect to the first is configured to refract said first and second rays in a substantially parallel manner. The isolator is configured such that the first ray comprises an e-ray with respect to the first stage and an o-ray with respect to the second stage, and the second ray comprises an o-ray with respect to the first stage and an e-ray with respect to the second stage, thereby substantially reducing the effects of polarization mode dispersion.

Abstract: An isolator is disclosed that features a single birefringent correction element. The correction element is configured to eliminate differential group delay and walk-off simultaneously.

Abstract: A method and apparatus for multiplexing/de-multiplexing optical signals is disclosed. The disclosed devices do not require active components. The devices may be used on their own or as part of a larger system such as a multi-stage mux/demux, an optical switch, or router. The optical device includes a linear polarizer, wave plates and a beam displacer/combiner. The wave plates optically couple to the linear polarizer. The wave plates rotate both odd and even channel components of an optical beam between a linear and an orthogonal relationship depending on the propagation direction. Each wave plate has a selected length and index of refraction determinative of a free spectral range which correspond to a spacing between adjacent gridlines of the selected wavelength grid. Each of the wave plates is tuned to even symmetry with the selected wavelength grid.

Abstract: An optical polarization beam splitter comprises a first optical fiber having an end defining a first optical axis, a second optical fiber having an end defining a second optical axis, and a third optical fiber having an end defining a third optical axis parallel to and spaced apart from the second optical axis. A collimating lens is disposed along the first optical axis positioned to form a collimated optical beam from the first optical fiber. A focussing lens is disposed along a path of the collimated optical beam. A birefringent walk-off crystal has a first face adjacent to the focussing lens and a second face located at a focal plane of the focussing lens and in contact with the ends of the second and third optical fibers.

Abstract: An optical receiver may include a photodector defined on a multilayer semiconductor structure. A first electrode may be formed by at least two substantially concentric conductive rings electrically coupled to one another and to a portion of a first layer of the multilayer semiconductor structure. A second electrode may be coupled to a second layer of the multilayer semiconductor structure and configured to transfer current generated by the photodetector in response to optical emissions. A method of fabricating such an optical receiver is also disclosed.

Abstract: Disclosed is a fiber optic coupler which includes a fused, stretched, and twisted biconical tapered region; a first pair of fiber pigtail ends extending from a first end of said biconical tapered region; a second pair of fiber pigtail ends extending from a second end of said biconical tapered region; and polarization dependent loss preclusion means disposed within said biconical tapered region. Further disclosed is a method for forming the polarization insensitive coupler as described.

Abstract: A modular approach to the design of motion modules, e.g., positioning elements, is disclosed which allows a single positioning element to be integrated into a number of multi-axis configurations through combination with other basic positioning elements all of which share a modular interlocking feature. The motion module includes a base and a mobile stage. The base includes an exterior surface on which a first interconnector is located. The mobile stage includes an exterior surface and a second interconnector. The mobile stage is rotary or linearly positionable with respect to the base The second interconnector is located on the exterior surface of the mobile stage, The first and the second interconnector are mutually engagable With second and first interconnectors of other motion modules for stackable interconnection therebetween.

Abstract: Disclosed is an apparatus for detecting near-visible frequency light comprising a sensor which includes a near-visible to visible light conversion phosphor defining an active area and a covering having a thickness, the covering adapted to substantially protect the phosphor from degradation. The phosphor extends to within about a first distance of a flush portion of a first edge, the first distance corresponding approximately to the thickness of the covering. In an alternative embodiment, the active area comprises an aperture.

Abstract: An interferometer and related methods for wavelength monitoring are disclosed. The interferometer may be used for the wavelength monitoring or as part of a wavelength feedback and control circuit for an optical signal source. The device operates by creating an output beam on which constructive and destructive optical interference may be detected. The optical interference is generated by a monochromatic beam split into a first beam traversing a stationary path and a second beam traversing a path of variable length. The first and second beams are then recombined to create constructive/destructive interference which may be measured by a detector and correlated with a processor to determine the output wavelength of the optical source. The maximum and minimum of the variable path length are precisely controlled due to use of a micro-positionable semiconductor retroreflector or mirror.

Abstract: An optical polarization beam splitter comprises a first optical fiber having an end defining a first optical axis, a second optical fiber having an end defining a second optical axis, and a third optical fiber having an end defining a third optical axis parallel to and spaced apart from the second optical axis. A collimating lens is disposed along the first optical axis positioned to form a collimated optical beam from the first optical fiber. A focussing lens is disposed along a path of the collimated optical beam. A birefringent walk-off crystal has a first face adjacent to the focussing lens and a second face located at a focal plane of the focussing lens and in contact with the ends of the second and third optical fibers.

Abstract: The present invention provides an apparatus for passively stabilizing the tuning element in tunable lasers. Lasers stabilized using the passive stabilization of the tuning element exhibit reduced mode hop and increased wavelength stability during temperature variations of the laser or surrounding environment. The stabilization makes the laser suitable for a broad range of applications including optical signal generators and optical multimeters.