A damping circuit having an input terminal and an output terminal is described. The damping circuit comprises a driver having an input and an output; an RC circuit coupled between the input terminal and the output; and a resistor coupled between the output and the output terminal, wherein the RC circuit delays passing a signal from the output terminal to the input terminal and a low impedance associated with the driver generally reduces ringing.

A method includes moving a heat-assisted magnetic recording head relative to a magnetic recording medium comprising a plurality of tracks, the head comprising a reader and a writer including a near-field transducer (NFT) optically coupled to a laser diode, the writer comprising a center which is laterally offset relative to a center of the reader to define a writer-reader offset (WRO) therebetween. Patterns are written to a particular track at a plurality of laser diode current levels. The patterns are read and a WRO value is calculated at a peak amplitude position for each of the laser diode current levels. A slope of the WRO values is determined with the laser current diode levels. A health condition of the NFT is determined by determining if the slope is greater than a predetermined threshold indicative of non-uniform activation across the NFT.

A recording method including: emitting laser light from an optical fiber array to record an image formed of writing units with moving a recording target and the optical fiber array relatively using a recording device including a plurality of laser light-emitting elements and an emitting unit including the optical fiber array, in which a plurality of optical fibers configured to guide laser light emitted from the laser light-emitting elements are aligned, wherein a maximum length of the writing unit along a sub-scanning direction is controlled with set values of: a duty ratio and a cycle of a pulse signal input to the emitting unit; recording energy applied to the recording target; and a spot diameter of the laser light, to record with overlapping an edge of the writing unit with an edge of the adjacent writing unit in the sub-scanning direction.

A recording method including: emitting laser light from an optical fiber array to record an image formed of writing units with moving a recording target and the optical fiber array relatively using a recording device including a plurality of laser light-emitting elements and an emitting unit including the optical fiber array, in which a plurality of optical fibers configured to guide laser light emitted from the laser light-emitting elements are aligned, wherein a maximum length of the writing unit along a sub-scanning direction is controlled with set values of: a duty ratio and a cycle of a pulse signal input to the emitting unit; recording energy applied to the recording target; and a spot diameter of the laser light, to record with overlapping an edge of the writing unit with an edge of the adjacent writing unit in the sub-scanning direction.

The present disclosure generally relates a method for removing a smear from a write head in a HAMR system. The smear can be removed by sufficiently heating the smear in an oxidative atmosphere to oxidize the smear. The material buildup that forms the smear has carbon, that when oxidized, is a gaseous product that leaves the write head with a reduced and/or eliminated smear. The heating occurs when the head is disposed in the parking location on the ramp remote from the magnetic media. Heating is possible using the same heat source for the HAMR head that is used to write data to the magnetic media.

The present disclosure generally relates a method for removing a smear from a write head in a HAMR system. The smear can be removed by sufficiently heating the smear in an oxidative atmosphere to oxidize the smear. The material buildup that forms the smear has carbon, that when oxidized, is a gaseous product that leaves the write head with a reduced and/or eliminated smear. The heating occurs when the head is disposed in the parking location on the ramp remote from the magnetic media. Heating is possible using the same heat source for the HAMR head that is used to write data to the magnetic media.

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.

An information recording/playback device includes a recording pulse generation unit generates a recording pulse based on a multi-value modulation data, and a data recording unit records the mark on the recording medium based on the recording pulse. The data recording unit executes recording processing of setting sizes of all of marks to be recorded on the recording medium to a size equal to or smaller than a spot size at a half level of a maximum value of a two-dimensional light intensity distribution of a beam spot, and executes data recording processing of forming recording regions in modes having different densities of recording marks according to the levels of the multi-value modulation data.

An information recording/playback device includes a recording pulse generation unit generates a recording pulse based on a multi-value modulation data, and a data recording unit records the mark on the recording medium based on the recording pulse. The data recording unit executes recording processing of setting sizes of all of marks to be recorded on the recording medium to a size equal to or smaller than a spot size at a half level of a maximum value of a two-dimensional light intensity distribution of a beam spot, and executes data recording processing of forming recording regions in modes having different densities of recording marks according to the levels of the multi-value modulation data.

An optical isolator has a first optical property with respect to transmitted components of the light traveling towards a target and a second optical property with respect to reflected components of the light traveling towards the laser. The second optical property suppresses the reflected components of the light. The optical isolator can be used in applications such as heat-assisted magnetic recording and LIDAR.