Intel Corporation

Maxtor Corporation

Mark Rice

Mark E McDonald

Andrew J Daiber

Brad Vaughn Johnson

Jiann-Chang Lo

Alexander V Tuganov

Paul Chi-Hwa Lin

Don Brunnett

Yu Sun

William J Kozlovsky

William B Chapman

Bernhard Hiller

Richard Yaeger

Doug Sprock

Rob Carney

Apparatus and methods usable for wavelength references and measurement of wavelength of a light beam. The apparatus comprise at least two wavelength reference or filter elements positioned in a light beam, each wavelength reference element having a different free spectral range and operable to define a joint free spectral range, and a detector positioned in the beam after the wavelength reference elements. The joint free spectral range provided by the multiple wavelength reference elements results in a joint transmission peak that is centered at a unique wavelength, and maximum optical power detectable from the beam by the detector occurs at the center wavelength of the joint transmission peak.

Wavelength reference apparatus and method

A laser apparatus and method that uses active thermalization of a reflective element to minimize losses and provide wavelength stability. The laser comprises first and second reflectors defining an external cavity, and a compensating member coupled to at least one of the reflectors and configured to thermally position one reflector with respect to the other reflector. The compensating member may be coupled directly to the first reflector and configured to position first reflector with respect to said second reflector. The thermal positioning may be carried out by a thermoelectric controller operatively coupled to the compensating member and configured to thermally adjust the compensating member by heating or cooling thereof. The laser apparatus may comprise a gain medium having first and second output facets and emitting a coherent beam from the first output facet along an optical path. The first reflector is positioned in the optical path, with the second output facet and first reflector defining an external cavity. The compensating member may be thermally conductive and have a high coefficient of thermal expansion.

Laser apparatus with active thermal tuning of external cavity

A disk drive having a control system which adjusts seek velocity profiles is disclosed. The seek velocity profile is adjusted based on the direction of the seek and the location of the target track. If the seek is away from the ramp, the seek velocity profile is not adjusted. If the seek is toward the ramp, the control system determines the location of the target track. If the target track is within a predefined distance of the ramp, and the transducer velocity exceeds a predetermined velocity, the seek velocity profile is adjusted to limit the deceleration current. The adjustment may be a preset factor, or may be a variable factor depending upon the distance from the target track to the ramp.

Asymmetric seek velocity profile to improve power failure reliability for rigid disk drive with ramp

A method and apparatus for reducing the acoustic output of a computer disk drive during a load or unload operation are provided. According to the invention, a pulse train having pulse widths that vary from one pulse to the next is provided to a voice coil motor while the transducer head is being loaded to or unloaded from the surface of the disk. According to one embodiment of the present invention, a proportional term equal to the inverse of the pulse width is supplied to the controller such that, with all other inputs to the controller being equal, a pulse train having pulses of equal total power are produced. By providing pulses of varying widths, the acoustic output of the disk drive is spread among multiple frequencies, and the amplitude at any one frequency is diminished as compared to a pulse train having pulses of equal width.

Method and apparatus for the acoustic improvement of the pulsed current method for controlling the velocity of a transducer head

An apparatus including a cavity optical length actuator to vary a cavity optical path length of a laser in response to an excitation signal having varying frequencies. The cavity optical length actuator induces intensity perturbations in an optical beam of the laser corresponding to the excitation signal. A sensor senses the intensity perturbations in the optical beam and generates a response signal corresponding to the intensity perturbations. A combiner combines the excitation signal and the response signal to generate an error signal.

Spread spectrum dither for locking to transmission peak in tunable laser

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.

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San Jose, CA, United States of America

Mark Rice