Abstract: According to one embodiment, a magnetic recording/reproducing device comprises a magnetic head including an assist element and configured to perform assist recording by applying assist power to the assist element, a rotation driver configured to perform rotation drive of the magnetic recording medium, a rotation number controller, and an assist power controller. The assist recording is performed under a first condition including a first rotation number and a first assist power, or under a second condition including a second rotation number which is different from the first rotation number and a second assist power which is different from the first assist power.

Abstract: A data storage device is disclosed comprising a head actuated over an energy assisted magnetic media comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A write operation to a first data sector is executed by applying a first current to a write coil of the head while the head is over a second data sector preceding the first data sector, wherein the first current comprises a first amplitude. A second current is applied to the write coil while the head is over the first data sector, wherein the second current comprises a second amplitude lower than the first amplitude.

Abstract: A disk drive apparatus determines a pattern of bits of a data signal applied to a magnetic write transducer of a heat-assisted magnetic recording apparatus. The magnetic write transducer applies a magnetic field to a recording medium in response to the data signal. A laser power signal is applied to a laser that heats the recording medium while the magnetic field is applied. The laser power signal is modulated based on the pattern of bits. The modulation reduces differences between track widths of recorded marks having different elapsed time values and/or increases a signal-to-noise ratio of the recorded marks having different elapsed time values.

Abstract: The present disclosure relates to pretreating a magnetic recording head to increase the lifetime of the magnetic media drive. A transparent smear is purposefully formed on the magnetic recording head to ensure the magnetic recording head does not overheat and lead to a short drive lifetime. The transparent smear is formed from material found in the magnetic media. The transparent smear is formed by pretreating the magnetic recording head with the transparent material from the magnetic media. The pretreating occurs without writing any data to the magnetic media. Once the transparent smear is in place, writing may occur. The magnetic recording head can be retreated at a later time should the transparent smear degrade. Furthermore, if an optically absorbing smear develop, it can be removed and a new transparent smear may be formed.

Abstract: Embodiments herein describe photonic systems that include a germanium photodetector thermally coupled to a resistive element. Current flowing through the resistive element increases the temperature of the resistive element. Heat from the resistive element increases the temperature of the thermally coupled photodetector. Increasing the temperature of the photodetector increases the responsivity of the photodetector. The bias voltage of the photodetector can be increased to increase the bandwidth of the photodetector. In various embodiments, the photodetector includes at least one waveguide to receive light into the photodetector. Other embodiments include multiple resistive elements thermally coupled to the photodetector.

Abstract: This disclosure is related to systems, devices, processes, and methods to optimize a laser power boost amplitude, a laser power boost duration, or both in a heat-assisted data recording device, such as in heat-assisted magnetic recording (HAMR). The amplitude and duration for the laser power boost may be determined for a specific portion of a write operation, such as a first sector of the write operation. During operation of a data storage device, the laser power boost may provide additional power to the laser for the specific portion. Once the laser power boost duration has elapsed, the data storage device may continue providing power to the laser at the normal power input range of the laser. The laser power boost settings may be determined on a per head per zone basis, per track basis, or another configuration.

Abstract: A method includes generating, during manufacture of a heat-assisted magnetic recording (HAMR) disk drive, a temperature compensation equation for a compensation factor using initial operating currents supplied to a laser diode of the disk drive at different initial operating temperatures and an efficiency value based on the initial operating temperatures. The operating currents are representative of currents for recording data to or erasing data from a magnetic recording medium. The temperature compensation equation is stored in the disk drive. A subsequent efficiency value is determined based on at least one of the initial operating temperatures and an operating temperature differing from the initial operating temperatures. An updated compensation factor at the operating temperature is determined during field operation using the temperature compensation equation and the subsequent efficiency value. An updated operating current is calculated using the updated compensation factor and the operating temperature.

Abstract: Pseudorandom bit sequences are recorded to a heat-assisted recording medium at a laser power that is stepped while recording the pseudorandom bit sequences. The pseudorandom bit sequences are read from the heat-assisted recording medium to determine timing differences between bits written before and after the laser power is stepped. A thermal gradient of bits written to the heat-assisted recording medium is determined based on the timing differences.

Abstract: A slider configured for heat-assisted magnetic recording comprises a magnetic writer, a near-field transducer, and an optical waveguide coupling the near-field transducer to a light source. The writer is situated proximate the near-field transducer at an air bearing surface of the slider and comprises a first return pole, a second return pole, and a write pole situated between and spaced apart from the first return pole and the second return pole. A structural element is situated at or near the air bearing surface between the write pole and one of the first and second return poles. The structural element comprises a cavity. A thermal sensor is disposed in the cavity. The thermal sensor is configured for sensing contact between the slider and a magnetic recording medium, asperities of the medium, and output optical power of the light source.

Abstract: A heat-assisted magnetic recording head is moved relative to a magnetic recording medium. The medium comprises a plurality of sectors. The sectors define a plurality of sector groups distributed around a circumference of the medium. The sectors of each sector group are written using different operational currents supplied to a laser diode of the head such that at least one sector from each sector group is written using one of the different operational currents. For each of the different operational currents, an average write performance metric is calculated for all sectors written at each of the different operational currents. A particular operational current of the different operational currents is determined that results in a best average write performance metric.

Abstract: A slider configured for heat-assisted magnetic recording comprises an air bearing surface (ABS), a writer, and a close point of the writer. A plurality of heat producing or dissipating components are situated a predetermined distance from a vertical plane that is normal to the ABS and aligned with the close point. A location of the writer close point remains substantially consistent irrespective of which of the plurality of heat producing or dissipating components are energized.

Abstract: An operational laser power for a heat-assisted, magnetic recording head is selected based on a function of a write quality metric versus laser power. The write quality metric of data written to a magnetic recording medium is monitored at the operational laser power. Responsive to the write quality metric satisfying a threshold, a power difference between the operational laser power and an offset laser power is determined. The offset laser power corresponds to a point of the function where the write quality metric is approximately equal to the threshold. A maximum laser power is set for a calibration operation. The maximum laser power is based on the sum of the operational laser power and the power difference.

Abstract: Method and apparatus adaptively adjusting power levels of a data transducer in a data storage device. In some embodiments, an initial power value is applied to a powered element of a transducer to write user data from a host device to a rotatable data recording medium. An exception condition is declared responsive to a measured parameter. The transducer is used to read data from an evaluation track using a range of different input power values for the powered element. A different, new power value is selected for the powered element responsive to an error rate associated with each of the range of different input power values, with the new power value being lower than the initial power value. Thereafter, the new power value is applied to the powered element during a subsequent writing of user data to the rotatable data recording medium.

Abstract: A storage device includes a controller that directs incoming data to a storage location based on a capacity of a region or surface of a magnetic disc. According to one implementation, the storage device controller writes new data to data tracks in a first series of data tracks on the magnetic disc until a capacity condition is satisfied. Once the capacity condition is satisfied, the storage device controller writes new data to a second series of data tracks on the storage medium that are interlaced with data tracks of the first series.

Abstract: A data storage device may be configured with at least a heat assisted magnetic recording head that has a laser and is connected to a controller. The heat assisted magnetic recording head can be positioned proximal first and second data bits stored on an adjacent data storage medium. A first laser power may be applied by the laser in response to the first data bit being a different magnetic polarity than the second data bit and a different second laser power can be applied by the laser in response to the first and second data bits having a common magnetic polarity.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a laser configured to heat the disk while writing data to the disk. A temperature is measured, and a first input power is generated based on a first function of the measured temperature, wherein the first function compensates for a temperature dependent output power of the laser. A second input power is generated based on a second function of the measured temperature, wherein the second function compensates for a temperature dependent coercivity of the disk. The first input power is combined with the second input power to generate a write power applied to the laser while writing data to the disk.

Abstract: An apparatus includes a write element configured to apply a magnetic field to write data on a portion of a heat-assisted magnetic recording media in response to an energizing current. An energy source is configured to heat the portion of the media being magnetized by the write element. A preheat energizing current is applied to the write element during an interval before writing the data to the portion of the media. The preheat energizing current does not cause data to be written to the media and brings at least one of the write element and driver circuitry into thermal equilibrium prior to writing the data on the portion.

Abstract: Embodiments of the present invention generally relate to a HAMR device having two temperature sensors. The first temperature sensor is disposed adjacent a waveguide and is about two or more micrometers away from an air bearing surface. The first temperature sensor has a length, a width and a thickness, and the length is greater than the width and the thickness. The length of the first temperature sensor is substantially perpendicular to the waveguide.

Abstract: Changes in the thermal boundary condition near a close point of an ABS to a media indicate proximity of the ABS with the media. Before contact, heat conduction from the ABS is primarily through convective and/or ballistic heat transfer to air between the ABS and the media. After contact, heat flux primarily flows from the ABS to the media through solid-solid conductive contact. Further, a light source within a HAMR transducer head may create additional thermal variations within the transducer head. These thermal variations create temperature variations within the transducer head. Two resistance temperature sensors on the transducer head at varying distances from the close point and/or light source measure these temperature variations. A temperature difference between the two resistance temperature sensors indicates proximity of the close point to the media and/or light output.

Abstract: The embodiments disclose a patterned composite magnetic layer structure configured to use magnetic materials having differing temperature and magnetization characteristics in a recording device, wherein the patterned composite magnetic layer structure includes magnetic layers, at least one first magnetic material configured to be used in a particular order to reduce a recording temperature and configured to control and regulate coupling and decoupling of the magnetic layers and at least one second magnetic material with differing temperature characteristics is configured to control recording and erasing of data.

Abstract: An apparatus comprises a write transducer, an energy source, and a controller. The write transducer is configured to write data to a magnetic recording medium, and the energy source is configured to heat the magnetic recording medium while it is being written to by the write transducer. The controller is coupled to the write transducer and configured to adjust at least an operating power of the energy source to selectably cause bits having variable bit aspect ratios to be written to the magnetic media.

Abstract: Provided is an optical disc apparatus and an optical disc recording method, in which it is decided whether or not an optical disc recording medium is one of DVD-RW and DVD+RW when data is recorded in the medium. If it is decided that the medium is one of DVD-RW and DVD+RW, maximum length information is read out from a storage portion. The maximum length information contains a previously set maximum data length of data recorded to the medium by an optical pick-up portion in one recording operation. Data to be recorded is split into split data having a data length of the maximum data length or smaller. Further, an electric power value of a base electric power for controlling the semiconductor laser element to emit a laser beam with a bottom power is reset every recording operation of the split data.

Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk, the head comprising a fly height actuator (FHA). The disk drive further comprises control circuitry including disk access circuitry, wherein during a calibration operation, the disk access circuitry is configured into a calibration mode that increases a heating of the head, and a fly height of the head is measured periodically to generate periodic fly height measurements that vary due to the heating of the head. A dynamic fly height (DFH) write profile is generated based on the periodic fly height measurements. During a write operation, the disk access circuitry is configured into a write mode and a DFH control signal is generated and applied to the FHA based on the DFH write profile.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, wherein the head comprises a laser for heating the disk while writing data to the disk. The disk drive receives write commands, and increases a power of the laser to a write power for heating the disk while writing data to the disk. A calibration interval is adjusted based on the power applied to the laser over time, and the write power is calibrated at the calibration interval.

Abstract: A write head includes a cavity configured to couple a laser diode to the write head. A bottom of the cavity includes a heat conductive element configured to contact the laser diode, a plurality of thermal studs disposed below the heat conductive element, and a substrate disposed below the thermal studs. The heat conductive element, thermal studs, and substrate are thermally coupled to draw heat from the laser diode.

Abstract: A heat-assisted magnetic recording (HAMR) transducer is coupled with a laser for providing energy and has an air-bearing surface (ABS) configured to reside in proximity to a media during use. The HAMR transducer includes a waveguide optically coupled with the laser and an optical power monitor optically coupled with the waveguide. The waveguide directs energy from the laser toward the media. The optical power monitor is optically coupled with the waveguide. The optical power monitor for captures a portion of the energy, converts the portion of the energy to heat and measures a local temperature proximate to the optical power monitor.

Abstract: Apparatus and systems create differential drive signals suitable for HAMR data recording. A laser diode differential driver provides heating current pulses at a time ?1. The pulses energize a laser diode to pre-heat the magnetic medium to be written. Some embodiments duplicate portions of the laser diode circuit architecture to create a magnetic write head differential driver. The write head driver provides write current pulses to a magnetic write head in one direction with ?1 timing and in the opposite direction with ?2 timing. Both drivers utilize sets of reference voltages capable of being switched to one terminal or the other of the element to be driven. In the laser diode case, the common mode is split between the anode and cathode sections of the driver. A feedback element is added between the cathode and anode sections to provide current accuracy independent of the electrical characteristics of the selected laser diode.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, wherein the head comprises a laser operable to heat the disk while writing data to the disk. An initial laser power of the laser is configured. After a time interval, an operating laser power of the laser is measured, and when the operating laser power falls below the initial laser power, a control signal applied to the laser is first adjusted until the operating laser power substantially matches the initial laser power. After first adjusting the control signal applied to the laser, a quality metric representing a recording quality of the head is measured, and when the quality metric indicates a poor recording quality, the control signal applied to the laser is second adjusted so that the operating laser power exceeds the initial laser power.

Abstract: Techniques for improving the recording quality during heat assisted magnetic recording (HAMR) by monitoring the power of a source used to heat a storage medium are described. In one example, a source emits electromagnetic radiation. A waveguide transmits the electromagnetic radiation onto a surface of a magnetic media. A photoresistive material is proximately located to the waveguide. The resistance of the photoresistive material varies based on the intensity of electromagnetic radiation propagating through the waveguide. The power of the source is determined by measuring the resistance of the photoresitive material. The power of the source is adjusted based on the determined power.

Abstract: The magnetic disk unit includes: a magnetic recording medium; a thermally-assisted magnetic recording head including a magnetic pole applying a recording magnetic field to the magnetic recording medium and a heating element heating the magnetic recording medium; and a controller allowing the heating element to perform a continuous heating operation at a first temperature for a first time period, and halting the heating operation of the heating element or allowing the heating element to perform a heating operation at a second temperature lower than the first temperature for a second time period that follows the first time period, the first time period having a length substantially equal to or less than a length of a time required for the magnetic recording medium to rotate one turn, and the second time period having a length substantially equal to or more than the length of the first time period.

Abstract: A thermally-assisted magnetic recording (HAMR) disk drive uses a thermal sensor to accurately monitor laser power during writing. The disk drive controller, or a separate processor, computes a prediction of the laser power from a history of laser power settings. This predicted value is compared with the measured value from the thermal sensor. If the difference is too large or too small, indicating that the laser power is too high or too low, an error signal is sent to the disk drive controller. The disk drive controller may adjust the laser power setting and initiate a re-write of the data. The predicted laser power is calculated from a convolution of a sequence of current and prior laser power settings with a sequence of coefficients. A calibration process generates the sequence of coefficients when the disk drive is idle or just after it is powered on.

Abstract: Apparatus and method for light source power control during the writing of data to a storage medium. In accordance with various embodiments, a data recording head is provided having a magnetic transducer and a light source. The light source is driven at a first power level to irradiate an adjacent storage medium prior to the writing if data to the medium using the magnetic transducer. The first power level is insufficient to alter a magnetization state of the medium. The light source is subsequently transitioned to a higher, second power level to irradiate the storage medium during the writing of data to said medium using the magnetic transducer, the second power level being sufficient to alter said magnetization state of the medium.

Abstract: A heat-assisted magnetic recording system may include, but is not limited to: at least one magnetic recording read/write head; at least one laser diode configured to illuminate at least a portion of at least one magnetic recording medium; at least one laser power level sensor configured to detect a power level of the at least one laser diode; and a controller configured to modify one or more power level settings associated with the at least one laser diode in response to one or more output signals of the at least one laser power level sensor.

Abstract: A disk drive is disclosed comprising a disk, a head comprising a laser operable to heat the disk while writing data to the disk, and a fly height actuator (FHA) operable to actuate the head vertically over the disk. A setting is applied to the FHA to maintain a fly height of the head. An approximately zero bias laser power is applied to the laser during a non-write mode, and a first write laser power is calibrated during a write mode. A non-zero bias laser power is applied to the laser during the non-write mode, and a second write laser power is calibrated during the write mode. When the second write laser power is different than the first write laser power, the setting of the FHA is adjusted to adjust the fly height of the head.

Abstract: A driver circuit configured to generate a drive signal for an optical source comprises an overshoot controller that provides an amount of overshoot for a given logic state of the drive signal as a function of a duration of at least one previous logic state of the drive signal. The drive signal may alternate between a first logic state associated with a first operating mode of the optical source and a second logic state associated with a second operating mode of the optical source. The overshoot controller may be configured to provide amounts of overshoot for respective instances of the first logic state that are proportional to the durations of their respective immediately preceding second logic states. The driver circuit may be implemented in a heat-assisted magnetic recording system in which the optical source alternates between on and off states associated with respective magnetic write and magnetic read modes.

Abstract: A write head includes a cavity configured to couple a laser diode to the write head. A bottom of the cavity includes a heat conductive element configured to contact the laser diode, a plurality of thermal studs disposed below the heat conductive element, and a substrate disposed below the thermal studs. The heat conductive element, thermal studs, and substrate are thermally coupled to draw heat from the laser diode.

Abstract: According to one embodiment, a magnetic recording device includes: a magnetic recording medium provided with data regions for data recording; a light output module which outputs an optical signal to be applied to a recording position where recording data is recorded of the data regions; a write head which records the recoding data at the recording position magnetically; a light quantity setting module which sets a light quantity value of the optical signal output from the light output module; a heat-assisted recording controller which performs a control so that the recording data is recorded by the write head at the recording position which is heat-assisted by applying an optical signal with the set light quantity value; and a controller which adjusts the light quantity value of the optical signal set by the light quantity setting module using the recording position being a part of the data regions.

Abstract: Apparatus and method for light source power control during the writing of data to a storage medium. In accordance with various embodiments, a data recording head is provided having a magnetic transducer and a light source. The light source is driven at a first power level to irradiate an adjacent storage medium prior to the writing if data to the medium using the magnetic transducer. The first power level is insufficient to alter a magnetization state of the medium. The light source is subsequently transitioned to a higher, second power level to irradiate the storage medium during the writing of data to said medium using the magnetic transducer, the second power level being sufficient to alter said magnetization state of the medium.

Abstract: Various embodiments of the present invention provide single-ended and differential current drivers for heat assisted magnetic recording and other applications. For example, a current driver is disclosed that includes an upper output terminal and lower output terminal, a number of current switches operable to selectively contribute electrical currents through the upper and lower output terminals, a control input for each of the current switches operable to control the electrical currents, and a voltage supply operable to establish a voltage across the upper and output terminals.

Abstract: Embodiments of optical disc drives are described that perform automatic forward sense calibration of write laser power using a sample and hold sampling strategy that is automatically determined based on an automatically selected write strategy. Embodiments of the described optical disc drive may be dynamically configured to support any optical disc media, any write mode, and any write strategy. The write strategies supported may include dynamically changing write speeds and/or write power levels across the respective optical media tracks. As the optical drive is automatically configured for a selected write media/write mode/write strategy, the sample and hold sampling delays used to control the sampling of a forward sense feedback signal are also automatically configured, thereby allowing each forward sense sampling point to be aligned with an area of the forward sense feedback signal that corresponds to a power level of interest and that avoids distortion in the feedback signal.

Abstract: An optical disc drive includes a memory stored a write strategy, a converting unit which converts a recording data into a recording pulse based on the write strategy stored in the memory, an inspection unit which inspects a state of the recording data from a reproducing signal, a recording controller which executes a recording operation to record the recording data by applying a laser beam corresponding to the recording pulse to an optical disc, suspends the recording operation, judges whether correction of the write strategy according to an inspection result of the inspection unit is necessary, and restarts the recording operation after the write strategy saved in the memory is collected, and a correction unit which corrects the write strategy saved in the memory when the correction of the write strategy according to an inspection result of the inspection unit is necessary.

Abstract: The wavelength is monitored using a spectrum analyzer in a state where a semiconductor laser is being driven while changing the light-emitting time of the semiconductor laser. When the internal temperature of the semiconductor laser estimated from a measured wavelength falls out of a preset temperature range, a gimbal assembly is identified as a defective product.

Abstract: A near-field transducer (NFT) has a primary tip that concentrates the oscillating charge of the NFT onto a substrate, such as magnetic recording medium, to heat regions of the medium, and a secondary tip. The secondary tip is located close to a temperature sensor, such as an electrical conductor whose resistance varies with temperature. The temperature sensor senses heat from the secondary tip and thus properties of the substrate like surface topography and the presence or absence of metallic material. The NFT can be part of a bit-patterned media (BPM) thermally-assisted recording (TAR) disk drive. The temperature sensor output is used to control the write pulses from the disk drive's write head so the magnetic write field is synchronized with the location of the magnetic data islands.

Abstract: An information recording/reproducing method includes: setting light beam power from a light source, to second power P2, which is weaker than first power P1, and detecting the number of the recording layers provided for an optical disc; controlling an objective lens to focus the light beam on one recording layer which is the closest to the objective lens, in a condition that the detected number of the recording layers ?3; setting the power of the light beam to third power P3, between P1 and P2; specifying the number of the recording layers provided for the optical disc on the basis of layer information, which is information associated with the one recording layer; and setting the power of the light beam to P1, reading the layer type information recorded in advance in the one recording layer, and specifying a disc type based on the read layer type information.

Abstract: In a method and an apparatus for inspecting a thermally assisted magnetic recording head element, a specimen is mounted on a table movable in a plane of a scanning probe microscope device, evanescent light is generated from a portion of light emission of evanescent light of the specimen, scattered light of the evanescent light is detected by moving the table in the plane while a cantilever of the scanning probe microscope having a probe is vertically vibrated in the vicinity of a surface of the specimen, and an intensity distribution of the evanescent light emitted from the portion of light emission of evanescent light or a surface profile of the portion of light emission of evanescent light of the specimen is inspected using position information of generation of the evanescent light based on the detected scattered light.

Abstract: A writing method for an optical disk drive includes receiving a command to write a disc; implementing an optimum power control (OPC) test for a predetermined data transfer rate to obtain a relation of a beta parameter to writing power; acquiring a writing power for the predetermined data transfer rate with a target beta parameter; calculating the energy area ratio of writing strategies for every data transfer rate; multiplying the energy area ratio by the writing power for the predetermined data transfer rate to produce the writing power for every data transfer rate; and compensating the writing power with automatic writing control.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, wherein the head comprises a laser for heating the disk while writing data to the disk. The disk drive receives write commands, and increases a power of the laser to a write power for heating the disk while writing data to the disk. A calibration interval is adjusted based on the power applied to the laser over time, and the write power is calibrated at the calibration interval.

Abstract: An apparatus includes a slider including an air bearing surface and a waveguide configured to receive light from a light source, a sensor positioned to receive a portion of light emitted by the light source prior to the light exiting the slider at the air bearing surface, and a controller controlling the light source power in response to a characteristic of the sensor.

Abstract: A magnetic head slider includes a near-field light generator, an incorporated heater is activated to thermally-expand the magnetic head slider so that a first protrusion is generated on the air bearing surface, and a second protrusion protruding from the first protrusion is generated by a thermal expansion of the near-field light generator. A standard signal is written to a recording medium with a predetermined magnetization. A relation between a residual magnetization of the standard signal and a power of the heater is obtained by lowering the magnetization of the standard signal by heating the recording medium with the near-field light while light output of laser light is maintained to be constant and the power of the heater is varied. Further, a relation between the first spacing and the residual magnetization is obtained.

Abstract: A hard disk drive includes a recording medium and a thermally assisted type magnetic head. The controller determines one output current of a photodiode as a first saturated output current, the one output current being defined where temperature measured by a temperature sensor is a first temperature and where signal-to-noise-ratio (SNR) of the reproducing signal current of the reproducing element is saturated with respect to an increase in output current of the photodiode, and another output current of the photodiode as a second saturated output current, the another output current being defined where temperature measured by the temperature sensor is a second temperature, which is different from the first temperature, and where SNR of the reproducing signal current of the reproducing element is saturated with respect to an increase in the output current of the photodiode.