International Business Machines Corporation

Intel Corporation

Neophotonics Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Jiann-Chang Lo

Michael Servedio

James Michael Hammond

James E Boyette, Jr

Wayne Isami Imaino

Fu-Ying Huang

Andrew J Daiber

James Christopher Mahlbacher

Mark Rice

Robert Edward Brown

Christian J Bunker

Hans-George H Kolan

Yongkang Gao

Anand S Ramalingam

William J Kozlovsky

Roger William Wood

Steven A Keller

Yuet-Ying Yu

Matthew Taylor White

William B Chapman

Douglas A Sprock

Ali Reza Taheri

Paul Chi-Hwa Lin

Timothy J O'Leary

Doug Sprock

Rob Carney

James Edward Boyette, Jr

A tunable solid state laser device are described comprising a semiconductor based gain chip and a silicon photonic filter chip with tuning capability. The silicon photonic filter chip can comprises an input-output silicon waveguide, at least two ring resonators formed with silicon waveguides, one or more connecting silicon waveguides interfacing with the ring resonators, a separate heater associated with each ring resonator, a temperature sensor configured to measure the chip temperature, and a controller connected to the temperature sensor and the separate heaters and programmed with a feedback loop to maintain the filter temperature to provide the tuned frequency. The one or more connecting silicon waveguides are configured to redirect light resonant with each of the at least two ring resonators back through the input-output silicon waveguide. Corresponding methods are described for the control of the laser frequency. Improved structures of the SiPho multiple filter chip involve a Zagnac interferometer.

Method for wavelength control of silicon photonic external cavity tunable laser

According to embodiments of the present invention, an external cavity laser includes one or more tuning elements. At least one modulated voltage signal or dither is used to lock the transmission peak of the two tuning elements to each other. The wavelength of the laser also may lock onto the lock transmission peaks. In embodiments in which two dither signals are used, the dither signals may be orthogonal to or independent of each other. The two dither signals may produce two control signals to align the transmission peak of one filter to the transmission peak of another filter and the lasing mode of the laser to the aligned filters.

External cavity laser tuning element dither servo control

A tunable external cavity laser apparatus and method of laser operation. The apparatus includes a gain medium having first and second facets defining a facet laser cavity in which a first portion of light is internally reflected to produce a first lasing condition having a first reflection phase. A reflective element is positioned opposite the second facet of the gain medium, forming an external laser cavity defined by the first facet and reflective element. A second portion of light is internally reflected within the external cavity to produce a second lasing condition having a second reflection phase. A phase adjustment means is employed to adjust the first reflection phase relative to the second reflection phase so as to control a characteristic of the output beam emitted from the apparatus, such as the power output level of the beam. In one aspect, the relative phase is adjusted by controlling the temperature of the gain medium.

Laser facet phase control

A method for tuning a laser via a temperature control loop that linearizes a non-linear characteristic of a thermal electric cooler (TEC) element used to adjust the temperature of tuning components and corresponding laser apparatus. One or more TEC elements are thermally coupled to respective tuning components, such as etalon filters. The TEC elements provide a heat transfer function (cooling rate) in response to a received electrical input (drive signal), wherein the relationship between the cooling rate and the drive signal is non-linear. An un-compensated drive signal produced by the control loop is compensated such that the open loop gain of the control loop is linearized via a linearizer control block. In effect, the non-linear transfer function of the TEC element is cancelled out by the linearizer control block to produce a linear relationship between the cooling rate and the drive signal. This open loop gain linearization enables tuning events such as channel slewing, and laser start-up operations to be performed with reduced tuning overshoots and undershoots that would otherwise result from the non-linear TEC transfer function characteristic.

Thermoelectric cooler linearization in a tunable laser

A servo technique for concurrently providing wavelength locking and stimulated Brillouin scattering (SBS) suppression in an external cavity laser. Respective wavelength locking and SBS suppression signals are generated by a controller and combined into a composite drive signal. The composite drive signal is used to drive an optical path length adjustment element to modulate the optical path length of the laser cavity. The wavelength locking and SBS suppression portions of the drive signals produce concurrent modulations of the laser optical path length having different modulation frequencies and causing different frequency (wavelength) excursions. These modulations produce corresponding wavelength and intensity amplitude modulations in the laser's output. A feedback signal indicative of the intensity amplitude modulations is filtered to attenuate the portion of the signal due to the SBS suppression modulation, and is received as a tuning feedback signal by the controller. In response, the control provides a tuning adjustment signal to adjust the frequency of the laser.

Servo technique for concurrent wavelength locking and stimulated brillouin scattering suppression

Disk drive with mode canceling actuator

A fixture for testing circuits includes a rectangular array of conductive test pads, alternating with insulating areas in a checkerboard-like pattern. In a first embodiment, the entire array is printed on a central portion of a plastic membrane, with outer portions of the membrane carrying electrical lines from the test pads to connectors. In a second embodiment, the rectangular array is formed on surfaces of a number of closely packet plastic membranes, each of which has tabs extending away from the testing surface to connectors. The test fixture is generic, not being configured for testing a particular circuit configuration. To compensate for conditions of linear misalignment, the rectangular array is moved in a raster pattern having a size equal to the cell size of the rectangular array. To compensate for conditions of angular misalignment, the array may be rotated after such misalignment is measured, or test results may be compared with exemplary data for a number of misalignment conditions.

Method and apparatus for testing circuits having different configurations with a single test fixture

A method for determining whether short circuits exist among networks within a circuit under test includes bringing test probes into contact with each such network and switching groups of the test probes among two sides of a test circuit so that current flows through the testing circuit only when one of the test probes connected to one side of the testing circuit is connected by means of a short circuit to one of the test probes connected to the other side of the test circuit. This first test process establishes the fact that a short circuit exists without determining which networks are connected by the short circuit. A version of this method subsequently applies tests to individual networks to make this determination, in the event that a short circuit is found to exist by the first test process. Other versions of this method additionally determine which networks are connected to which other networks by short circuits.

Method and apparatus for determining short circuit conditions using a gang probe circuit tester

A linear actuator includes a stationary stator and an external armature moving with a coil moving within a magnetic structure. A linear bearing including a stationary track fastened to the stator and a moving track fastened to the armature extends on each side of the magnetic structure. In each linear bearing, balls rotate between the stationary and moving tracks with movement of the armature. During the process of manufacturing the linear actuator, the moving track of each linear bearing is loosely mounted to the armature, a pre-load force is applied to the moving track using a tool fastened to the armature, and the moving track is clamped in place so that the pre-load force is subsequently maintained.

Probe position actuator with an elongated stroke

An actuator assembly having two coils disposed between the poles of a voice coil motor (VCM) magnet for improved dynamic performance during settling and tracking operations in a disk drive. The two coils in the VCM are connected to separate current sources to allow the current flow in the two coils to have the same sense (clockwise or counterclockwise) or the opposite sense with respect to each other. When the current flows in the two coils have the opposite sense, excitation of the principal in-plane bending mode resonance of the actuator assembly is suppressed allowing the use of an increased servo bandwidth for settling and tracking operations of the disk drive. During seek operations of the disk drive, where maximum torque on the actuator is desirable, the coil currents in the two coils are chosen to have the same sense so that the forces on the actuator from the two coils are additive.

Dual coil rotary actuator

A system and method for using a piezoelectric (PZT) element to simultaneously actuate and sense a displacement of an arm assembly; e.g., an assembly for reading and writing data in a storage medium. The simultaneous actuating and sensing function of the PZT is achieved by adding a high-frequency excitation to a control signal which actuates the PZT. The control signal and the high-frequency excitation cause deformation of the PZT translating into arm displacement and cause the generation of an electrical response signal by the PZT. A bridge which simulates the reactance/resistance of the PZT receives the response signal and derives from it the displacement of the arm assembly. Suitable compensation techniques for active control of the PZT and for mitigation of mechanical vibrations and other disturbances experienced by the arm assembly may then be implemented based on the displacement.

Piezoelectric actuator for control and displacement sensing

Disclosed is a Mini Probe Positioning Actuator which is low in cost and mass, capable of high accelerations, relatively long stroke and compact packaging. The probe positioning actuator is composed of a pair of substantially parallel cantilevered beams, each beam being comprised of flexible, signal carrying cable formed of a polyimide composition which allows for the probe tip to be suspended from and form part of the armature of the actuator. The armature also includes a pair of oppositely wound coils intermediate the beams, which coils coact electromagnetically with a pair of spaced apart but fixedly positioned (relative to the coils/armature) magnets forming a motor for effecting armature and thus probe tip movement. The light mass of the coils and armature and the dual functional purpose of the suspension beams serves to make the probe actuator highly accurate and sensitive while allowing for reliable operation.

Miniature probe positioning actuator

In ultrasonic wirebonding apparatus, vibrations produced using a tubular piezoelectric (piezoceramic) actuator, driven by electrical current at an ultrasonic frequency, are used to provide energy for the wirebonding process. An assembly including means for mounting the actuator at a proximal end, the actuator itself, and a bonding tip extending from a distal end of the actuator, are moved by a carrier between the various points at which wirebonding is to occur. The bonding wire is fed through a passageway in this assembly. The carrier slides on a first carriage for movement into engagement with the workpiece. The first carriage slides in a first direction on a second carriage, which in turn slides in a second direction, to move between points at which wirebonding is to occur. The workpieces, such as circuit chips being manufactured, are moved into a workspace for wirebonding, are held therein during processing, and are subsequently removed from the workspace.

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Cupertino, CA, United States of America

Jiann-Chang Lo