Abstract: In the area of wavelength division multiplexing (WDM), the present invention relates to a demultiplexer/multiplexer based on a diffraction grating, in which a beam of light is separated into two orthogonally polarized sub-beams prior to beam collimation. Due to the characteristics of the beam splitting crystal, parts of the sub-beams overlap resulting in portions of the sub-beams becoming improperly polarized. Too alleviate the errors cause thereby, an iris is placed over the diffraction grating to eliminate the portions of the light that have been polarized improperly.

Abstract: A variable optical attenuator of the multiple-aperture type is disclosed. The attenuator comprises a thin element having a plurality of apertures therein. The plurality of apertures is arranged such that the size of most of the apertures increases along a distance of the thin element. In particular, the plurality of apertures is arranged in a carefully designed pattern wherein the percentage of transmitted light varies from one end of the pattern to the other. The variable optical attenuator is substantially wavelength and polarization independent.

Abstract: In optical amplifiers of the kind in which a so-called loop mirror is formed by connecting the ends of a loop of active optical fiber to a 3 dB coupler, improved signal-to-noise ratios are obtained by coupling pump energy into the loop without passing through the 3 dB coupler. The input signal and amplified output signal may be conveyed to and from the coupler by way of isolators connected to input and output ports of the amplifier. Alternatively, they may be conveyed by way of a circulator. Automatic gain control may be provided by means of a fiber grating, or other such wavelength-selective device, which reflects part of the amplified signal having a selected wavelength back into the loop, to provide lasing. The amount of energy so reflected may be controlled by an attenuator.

Abstract: An optical filter is disclosed having a pair of GRIN lenses disposed back to back, and having parallel end faces orthogonal to coaxial optical axes. Optical fiber tubes having optical fibers therein are disposed adjacent the GRIN lenses and have their inwardly facing end faces slant polished to lessen the effects of unwanted back reflections. This arrangement wherein optical axes of the optical fiber tubes are not parallel to the optical axes of the GRIN lenses is novel and inventive.

Abstract: A multiplexing/demultiplexing optical circuit provides a demultiplexed output spectrum of channels having a flat amplitude response without sacrificing optical power. A phased array implementation and a diffraction grating implementation both rely on a first dispersion of the beam to be demultiplexed and subsequent division of the wavelengths into channels. Local inversion is induced within each channel of the dispersed wavelengths about a channel central wavelength. After the wavelengths are spatially inverted, they are once again provided to a dispersion element or array effectively nullifying the dispersion effects across the channel band to provide output channels having a substantially “flat-tops”, while providing good channel separation through global dispersion of all the wavelengths.

Abstract: A tuned multiple fiber optical connector and a method for tuning same is disclosed. A first connector housing retains each of a first plurality of optical fiber ends in a predetermined location. The first connector housing has a first key element. A core of each of the first plurality of optical fiber ends is oriented in a predetermined fashion with respect to the first key element. A second connector housing retains each of a second plurality of optical fiber ends in a predetermined location. The second connector housing comprises a second key element. A core of each of the second plurality of optical fiber ends is oriented in a predetermined fashion with respect to the second key element. The first and the second connector housings are coupled such that the key elements are disposed in a predetermined relation one to the other.

Abstract: The invention discloses an optical deflection switch which uses the output focal plane of a lens more effectively. This is achieved by combining a tapered block of a light-transmissive material having a reflective surface and a second face, wherein the second face includes an input/output port and the reflective surface provides reflection of a beam of light passing through the input/output port into the tapered block with a first block of a light-transmissive material having a first face and a second face, wherein the first face includes an input port thereon for receiving a collimated beam of light and the second face is for providing total internal reflection of the beam of light in a first switching state and for acting as an output/input port for optical communication with the input/output port of the switching block when the total internal reflection is frustrated in a second switching state.

Abstract: A one-sided switch for redirecting light between adjacent ports. The switch uses a moveable refractor, in combination with a lens and a stationary reflector, to redirect light from one optical port to another. In a most simple embodiment light is redirected from one output port to another by repositioning the refractor in the optical path of the light and using only a single lens for collimating and focussing the light at the reflector and about the ports, respectively.

Abstract: A multi-mode interference coupler is disclosed for coupling light between ports. The MMI coupler is a planar waveguide having a first input port for launching light into a core of the planar waveguide which has first refractive index n1. The waveguide is dimensioned to have a response that confines light launched therein to a single mode in one dimension, and multi-mode in another dimension. Two other ports are provided for receiving light launched into and propagating through the core from the input port. A polymer cladding of a second material having a refractive index n2 covers at least a portion of the core. A heater is provided and is thermally coupled to the cladding for heating the cladding when a control signal is applied.

Abstract: This invention relates generally to custom optical filters such as filters relating to, flat-top WDM multiplexer/demultiplexers, flat-top and peaky comb filters or reconfigurable add & drop filters. The embodiment disclosed below is based on mid-dispersion wavelength bands processing, wherein the optical spectrum is dispersed in two steps; in-between these two steps, the wavelength bands are manipulated in the focal plane, for example by being moved, reflected, absorbed, inverted, magnified or reduced to achieve a particular result. A masked mirror or masked transmissive element selects wavelength by position. The mask shape for relatively complex filtering functions is much simpler than currently used for collimated beams because of the correlation between position and wavelength. Inversion of channel bands or movement of channel bands in two dimensions in the focal plane, in particular, enables the construction of numerous useful devices.

Abstract: A method and system is provided wherein an n channel system is equipped with n uncooled inexpensive lasers not requiring optical isolators provide optical signals to the n broad channels. Advantageously, the system can be installed at a reasonable cost to the first n users and be upgraded in number of channels and cost as the need for the system to evolve and grow arises. Each of the n uncooled lasers are tuned such that at ambient temperature, their central wavelength is below their respective channel mid wavelength.

Abstract: The method and apparatus forming the present invention allows for rapid analysis of the optical spectrum and its content by controlling the spectral position of a channel select element and using a ratiometric wavelength and power determination technique to accurately analyze the transmitted or elected portion of the optical spectrum. The channel select element can be either a transmissive or reflective device which can be tuned by way of a control signal. The system can be operated in either scan and post process mode or in a continuous feedback mode where the position of the channel select element is determined by the ratiometric wavelength determination system and used to control the wavelength position of the channel select element. The ratiometric wavelength and power determination system, in its typical form, is based on dividing the spectrally encoded optical signal into two parts.

Abstract: An optical coupling arrangement for use in an optical filter is disclosed wherein optical fibre are disposed only along one line in one orientation across an end face of an optical fibre tube having a slanted end face. By disposing slanted/polished optical fibre end faces along a line that is orthogonal to a longitudinal axis of the optical fibre tube, optimum coupling of light is achieved.

Abstract: Combinations of optically coupled Generalized Mach-Zehnder Interferometers (GMZIs) result in switches of greater switching capacity than an isolated GMZI. In a preferred form, the present invention provides a balanced non-blocking switch by using symmetrical configurations of optically coupled GMZIs, and also provides a cascaded non-blocking switch by cascading an N×N GMZI with a (N−1)×(N−1) non-blocking switch.

Abstract: This invention discloses to a multi-stage optical isolator having a large centrally disposed birefringent crystal and two smaller crystals sized to separate in a polarization dependent manner into sub-beams and combine light that is separated into sub-beams at an output end thereof. By providing a single large crystal centrally disposed, less alignment is required due to fewer alignment critical components being required. Furthermore, the isolator in accordance with this invention is well suited to high-power applications.

Abstract: A method and circuit is disclosed wherein two waveguides coupled to an optical resonant ring resonator are further coupled such that beams propagating therein interfere with one another to provide a desired output response. In one embodiment, multiplexed channels of light can be demultiplexed by the device described heretofore, or alternatively, the phase relationship between these two beams can be altered prior to their being combined to provide, for example, a linearized output response useful in applications such as wavelength locking. By varying the reflectivity of the FSR and the coupling ratios and/or by varying the phase relationship between the two beams, a variety of desired output responses can be realized.

Abstract: This invention relates to a method for filtering and to a variable slope optical filter for in-line use with an optical amplifier signal. The filter has a wavelength response that is substantially linear in slope within a band of operation wavelengths of the amplifier; the slope of the filter in an operating band of wavelengths is between zero and only one of a positive or negative number; furthermore the filter has an amplitude response that has an opposite and counter slope as a function of wavelength to that of a gain tilt of the amplifier within the operation band of wavelengths. The filter having means of operating on polarized light such that different wavelengths within a band of wavelengths within the operation band are subject to different levels of attenuation according to their polarization state. A wave plate having a predetermined thickness provides a relative polarization difference between two wavelengths of an incoming beam in a controlled manner.

Abstract: The present invention relates to a circuit for monitoring optical signals in a multiple channel system. A tunable band pass filter receives and input signal comprising multiple channels each having a different wavelength and predetermined channel spacing. Output from the tunable filter is directed to a second filter having a periodic response with wavelength, such as an etalon. The response is designed to block wavelengths of light corresponding to the channels, permitting noise in the inter-channel space to be measured by a detector. A reference circuit launches light from a broad band source through a Bragg grating into the tunable filter. The Bragg grating reflects a known reference wavelength. Light which passes from the reference source through the tunable filter is also passed through the second filter to a detector. When a notch is detected by the reference detector, the tunable filter is known to be tuned to the reference wavelength.

Abstract: An optical device is disclosed for interleaving or de-interleaving optical channels. A beam splitter combiner provides the function of splitting an incoming beam into two sub-beams which are then fed respectively to a first and second different GT resonator. The GT resonators provide a feedback signal in response to receiving the first and second sub-beams of light, respectively, to the beam splitter/combiner.

Abstract: A dental implant for anchoring in bone, wherein said bone comprises an outer cortical bone section and an inner cancellous bone section is made of a body of resorbable material such as coral, having a portion capable of being wedged into the cancellous bone. The body of coral has a generally cylindrical root portion, an emergent portion capable of being wedged into said outer cortical bone section, and a transgingival coronal portion being sized to extend beyond said emergent portion to end beyond a gingival layer, and an abutment portion and a head for retention of said prosthetic device at the other end, wherein said abutment portion meets said coronal portion at an interface beyond said gingival layer. The body of coral is substantially electroplated with a suitable plating material such as gold. At least some of the root portion is absent said plating material so as to allow the bone to enter the substantially plated body of coral to resorb and replace at least some of the coral.