Lucent Technologies Inc.

Ciena Corporation

At&t Bell Laboratories

Carl Edward Gaebe

Mindaugas Fernand Dautartas

Ernest Eisenhardt Bergmann

Richard Bendicks Bylsma

Rudolf Feodor Kazarinov

Gleb E Shtengel

Julie Sheridan-Eng

Walter Jeffrey Shakespeare

Kimberly Ann Miller

Sun-Yuan Huang

Thomas Stanley Stakelon

Rudolph Conrad Schweizer

Xian-Li Yeh

Bo Asp Moller Andersen

Christopher Eugene Young

Lisa Ann Peterson

Gary T Wiand

Sun-Huan Huang

Vladimire Pelekhaty

A temperature-compensated fiber grating package which provides a temperature dependant stress on a fiber Bragg grating to substantially compensate for temperature dependant variations of the Bragg wavelength. The package includes a base, a fiber grating bonded to the base, and a strut. The base is formed from a high thermal expansion material, and includes first and second spaced arms separated by a base portion. The strut is constructed from a low thermal expansion material is disposed between the first and second arms. The ends of the strut engage the interior surfaces of the arms to form left and right fulcrum points. The fiber grating is secured between the first and second arms. As temperature increases, the high thermal expansion material of the arms expands at a greater rate than the low thermal expansion material of the strut. The top portion of at least one of the arms thus pivots inward about a fulcrum point to place the temperature-dependant negative strain on the grating. The strain rate may be adjusted by appropriate positioning of the fulcrum points. According to another aspect of the invention a hinge may be provided adjacent one of the arms to substantially restrict flexing to that arm, thereby allowing adjustment of the compensating strain rate as well as an initial bias strain. According to another aspect of the invention, compensation for second order Bragg wavelength variations may be achieved by providing one of the arms with an inwardly extending angular top portion. Methods of making a temperature-compensated grating package consistent with the invention are also disclosed.

Temperature-compensated grating package and method of making the same

An optical filter including a plurality of dielectric layers is provided between first and second substrates. The substrates have a coefficient of thermal expansion that is greater than that of the dielectric layers, and the thicknesses of the substrates are selected to provide compensation for temperature-dependant variations in the center wavelength of the filter. A variety of substrate materials may be used. Quartz is advantageous as a substrate material because it has relatively low loss at wavelengths commonly used in telecommunication systems. Moreover, it is thermally and chemically stable, and has good adhesion to most dielectric films used as quarter and half wave layers. Further, quartz is mechanically tough, relatively inexpensive and readily available. The quartz substrate is cut from a crystal and has an orientation with reduced birefringence.

Athermal thin film filter

A lens system defined along an X-Y-Z coordinate system transforms an elliptical optical beam defined as exhibiting a first, fast axis component and a second, slow axis component, into an essentially circular optical beam. A first and a second lens intercepts the elliptical beam and a cruciform cylindrical lens is disposed to intercept the output from the second lens. The cruciform cylindrical lens has a fast lens and a slow lens, the fast lens having a first, front cylindrical surface oriented along the X axis of the coordinate system for magnifying the first, fast axis component, the slow lens having a second, rear cylindrical surface oriented along the Y-axis of the coordinate system for magnifying the second, slow axis component, wherein the magnifications are determined to provide an essentially circular output beam, the cruciform cylindrical lens disposed such that the optical beam exiting the second lens impinges the first, front cylindrical surface. At least one of the first lens, the fast lens, and the slow lens is adjusted in the Z-axis of the coordinate system to reduce any astigmatism in the optical beam caused by said transformation.

Astigmatic compensation for an anamorphic optical system

An optical filter including a plurality of dielectric layers is provided on a quartz substrate. Quartz is advantageous as a substrate material because it has relatively low loss at wavelengths commonly used in telecommunication systems. Moreover, it is thermally and chemically stable, and has good adhesion to most dielectric films used as quarter and half wave layers. Further, quartz is mechanically tough, relatively inexpensive and readily available. The quartz substrate is cut from a crystal and has an orientation with reduced birefringence. In addition, the thickness of the quartz substrate is selected to reduce temperature-related shifts in the center wavelength of the filter.

Optical filter having a quartz substrate

An erbium doped fiber amplifier includes a wavelength division multiplexer (WDM) which receives a data signal having a first wavelength through a first optical fiber which is single-mode at the first wavelength. Pump light supplied by an energy pump has a second wavelength shorter than the first. The pump light is provided through a second optical fiber which is multi-mode at the pump wavelength. The data signal and the pump light are multiplexed by the WDM. A third optical fiber is coupled to the WDM to receive the multiplexed output. The third fiber is single-mode at the data signal wavelength and multi-mode at the pump wavelength. The third fiber is erbium doped to amplify the input the data signal or is connected to a suitably doped fiber.

Direct free space pump signal mixing for EDFA

The present invention is a method for compensating for stress induced in optical components used to couple light egressing from the housing of optical modules employing, for example, a distributed optical isolator. It has been discovered that this induced stress may be counteracted by transmitting a balancing or compensating force so as to produce a counter-stress in the optical component. Preferably, the method uses pairs of circumferential laser welds judiciously formed a distance form the holder housing the optical component so as s to control the magnitude and direction of the applied compensating force and, hence, the counter-stress transmitted to the optical component. During welding, the effects of the induced stress are monitored and based upon any changes therein, pairs of laser welds are formed around the circumferential surface of the housing of the optical component until the induced stress is substantially reduced or eliminated.

Method for compensating stress induced in an optical component

The invention is a laser assembly for reducing distortion ripple. The assembly includes a spherical lens which has a portion of its surface made optically asymmetric to prevent multiple reflections of scattered light within the lens.

Analog laser assembly

The invention is a laser assembly with reduced distortion ripple. The assembly includes a spherical lens for collimating light emitted from the laser. The lens is made of a material which attenuates scattered light which is the source of ripple without appreciably affecting the main beam.

Semiconductor laser assembly with reduced ripple

An optical coupling arrangement comprises conventional focusing optics and an anamorphic (i.e., radially non-symmetric) lens positioned at the entrance to the optical fiber. The objective lens focuses the elliptical beam exiting a laser source and the anamorphic lens functions to change the beam mode from elliptical to circular. The positioning of the anamorphic lens at the fiber input (instead of the laser output) reduces the alignment tolerance problems associated with prior art arrangements.

Optical coupler using anamorphic microlens

A system for providing efficient coupling between an elliptical mode laser source and a single mode transmission fiber is disclosed. In one embodiment, the system comprises a cruciform cylindrical lens formed as a pair of perpendicular cylindrical lenses to provide for separate magnification of the 'fast' diverging component (i.e., this component passes through a 'fast' cylindrical lens) and the 'slow' diverging component of the beam (i.e., this component passes through a 'slow' cylindrical lens). By decoupling the magnification requirements of the components of the elliptical beam, the beam may be transformed into an essentially circular beam, appropriate for coupling into a single mode fiber. In one arrangement of the present invention, a coupling efficiency of approximately 90% is possible (as compared with prior art coupling efficiency of about 44%). In an alternative embodiment, the pair of cylindrical lenses may be replaced by a monolithic lens, formed to comprise orthogonal front and rear cylindrical surfaces.

Cruciform cylindrical lens for elliptical beam transformation

The invention is a circuit for monitoring the wavelength of a laser device such as a semiconductor laser. A piezoelectric resonator is positioned in the path of the light beam so as to form a Fabry-Perot cavity. The changes in the reflectivity of the cavity are detected as the resonator is driven by an oscillator circuit, and an error signal is produced in response thereto when the wavelength of the laser device strays from a desired value.

Monitoring wavelength of laser devices

An optical isolator comprises an input polarizer configured to pass light at a predetermined optical polarization axis to a Faraday rotator and thereafter through an output polarizer. A magnet is disposed remotely and laterally away from the Faraday rotator, such that the external field of the magnet maintains the magnetization of the Faraday rotator substantially saturated. In accordance with another aspect of the invention the output polarizer is rotatably adjustable to substantially fine tune the isolator to a given laser wavelength. To this end light is transmitted through an input polarizer, and through a Faraday rotator magnetized in a first magnetization direction so as to rotate the polarization axis of the light passing through the Faraday rotator. The output polarizer is rotatably adjusted until such time that substantially no light travels through the output polarizer. The Faraday rotator is then mangentized in a second magnetization direction such that it reverses the rotation of the polarization axis of the light traveling through it. The postion of the output polarizer is then fixed.

Optical isolator and alignment method

An apparatus minimizes the spherical aberration of a light beam emitted into an optical fiber from a light source such as a laser beam. The laser emits a light beam along a path of travel to an optical fiber used in a telecommunication system. A ball lens is positioned within the light beam path of travel, and has a front focal point. The laser is positioned in front of the front focal point such that the light beam emitted by the laser forms an intermediate paraxial focus point. A corrective lens is positioned adjacent the paraxial focus point so that the laser beam is introduced into an optical fiber with minimal spherical aberration and increased coupling efficiency. The corrective lens is displaced radially off-center to compensate for misalignment aberrations and coma.

Apparatus for minimizing spherical aberration of light beam emitted into

An apparatus minimizes the spherical aberration of a light beam emitted into an optical fiber from a light source such as a laser beam. The laser emits a light beam along a path of travel to an optical fiber used in a telecommunication system. A ball lens is positioned within the light beam path of travel, and has a front focal point. The laser is positioned in front of the front focal point such that the light beam emitted by the laser forms an intermediate paraxial focus point. A corrective lens is positioned adjacent the paraxial focus point so that the laser beam is introduced into an optical fiber with minimal spherical aberration and increased coupling efficiency.

A novel optical subassembly arrangement is proposed. The subassembly comprises a silicon-based submount including a plurality of openings for placement of the various optical components utilized to form the optical subassembly. In particular, a silicon wafer is processed (e.g., etched) using conventional techniques to simultaneously form a large number of individual submounts, each submount processed to include a number of openings. The silicon processing may be sufficiently controlled such that active alignment of the components is minimized. An important feature of the design, when associated with an isolated embodiment, is that the silicon submount is formed to include openings for both the laser and isolator optics such that the openings are disposed along a thermal transport path through the silicon substrate from an attached thermoelectric cooler (TEC). Therefore, the laser and isolator optics are maintained at the same operating temperature. In one embodiment, the TEC may be attached to the underside of the substrate so as to form a cantilever arrangement with the substrate. In this embodiment, the isolator's magnet may be disposed to surround the substrate in a manner such that physical contact is avoided. The physical separation between the substrate and the magnet thus frees the TEC from having to unnecessarily cool the magnet.

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Fleetwood, PA, United States of America

Carl Edward Gaebe