A slider configured for heat-assisted magnetic recording includes a laser diode optically coupled to a waveguide of the slider. A power supply is coupled to the laser diode. A preamplifier is coupled to the power supply. The preamplifier is configured to monitor a forward voltage across the laser diode while operating the laser diode at a constant current during a write operation, detect a change in the forward voltage indicative of laser power instability, and generate a signal in response to detecting the forward voltage change.

A magnet structure for a magnetic data storage medium erasing apparatus includes a first half comprising a first plurality of magnets arranged symmetrically, having polarization direction of adjacent magnets in quadrature and at an oblique angle with respect to a plane of symmetry. A second half comprises a second plurality of magnets arranged symmetrically, having polarization direction of adjacent magnets in quadrature and at an oblique angle with respect to the plane of symmetry. The second half is arranged symmetrically with respect to the first half, wherein the first half and the second half are separated by an air gap disposed about the plane of symmetry.

In an optical data transfer system, a beam modulator is configured to embed a set of data in an input beam. A multimode optical waveguide network has an in-coupling region for receiving the input beam. The multimode optical waveguide network is configured to guide the input beam to an out-coupling region of the multimode optical waveguide network. A spatial coherent detector is configured to measure a phase and an amplitude of an output optical field at multiple locations. The output optical field is at least partially defined by the input beam and thus exhibiting distortion effects caused by the passage of the beam through the multimode waveguide network. Signal processing is applied to an output of the spatial coherent detector, in order to compensate for the distortion effects, and thereby recover, from the output of the spatial coherent detector, the set of data embedded in the input beam.

The present disclosure generally relates to data storage devices, comprising: a magnetic tape; a tape head configured to write data to and read data from the magnetic tape; a first reel having a first interior surface; a second reel, wherein the first reel and the second reel are configured to wind and unwind the magnetic tape; one or more motors configured to actuate the first reel and the second reel; a first magnetic recording surface disposed on the first interior surface of the first reel; an actuating arm disposed between the first reel and the second reel; an actuator coupled to a distal end of the actuating arm; and a magnetic recording head disposed on the actuating arm. The magnetic recording head being situated a distance away from the actuator, wherein the actuating arm is configured to move about the actuator such that the magnetic recording head is able to contact the first magnetic recording surface to write data to and read data from the first magnetic recording surface.

A computer program product, system, and method are provided for direct resistance measurement of a magnetoresistive (MR) head of a storage drive in a storage system. In one embodiment, a voltage difference across the MR reader head is measured directly by applying an AC current to the MR head to generate an AC voltage across the MR head that can propagate through filter capacitors and be measured. In one embodiment, the voltage difference is amplified and the peak-to-peak voltage at the output of the amplifier is captured. Similarly, a reference voltage difference across a reference resistance is measured directly by applying a reference AC current to a reference resistance. The resistance of an MR reader head may be calculated directly as a function of the respective voltage differences without including the resistance of any bias resistors biasing the MR head.

A method of assembly a dual stage actuated suspension includes either applying an adhesive to a microactuator motor and then B-staging the adhesive, or applying an adhesive that has already been B-staged such as in film adhesive form to the microactuator then assembling the microactuator into a suspension and then finishing the adhesive cure. The adhesive can be applied to bulk piezoelectric material, with the adhesive being B-staged either before or after it is applied to the bulk piezoelectric material, and the piezoelectric material then singulated into a number of individual piezoelectric microactuators. The method allows greater control over how much adhesive is used, and greater control over spread of that adhesive and control over potential contamination, than traditional liquid epoxy dispense methods.

Systems and methods of laser bias calibration are presented. A preamplifier circuit may include a laser voltage monitor circuit and a laser bias control circuit configured to automatically adjust an output laser bias threshold voltage based on a monitored laser voltage. The laser bias control circuit may include a first differentiator circuit, a second differentiator circuit, and a threshold detection circuit. The preamplifier circuit may be utilized in a heat assisted magnetic recording device.

Disclosed herein are magnetic write heads for providing spin-torque-assisted write field enhancement, and hard disk drives comprising such magnetic write heads. Within the write gap, each magnetic write head comprises a main pole, a trailing shield, a spacer disposed between the main pole and the trailing shield, a non-magnetic layer disposed between the main pole and the trailing shield, and a magnetic DC-field-generation (DFG) layer adjacent to the spacer and disposed between the spacer and the non-magnetic layer. In some embodiments, the DFG layer is the only magnetic layer within the write gap that is not adjacent to the main pole or the trailing shield.

Bottom tracks are written to a recording medium using a first setting of a microwave assisted magnetic recording (MAMR) head. Top tracks are interlaced between and partially overlapping the bottom tracks using a second setting of the MAMR head, the second setting resulting in a narrower track width than the first setting.

A physical unclonable function (PUF) apparatus having magnetic particles is disclosed. The magnetic field data and the image view of the magnetic particles in the PUF apparatus are difficult to counterfeit. A PUF apparatus may be incorporated into a user-replaceable supply item for an imaging device. Further, a PUF reader may be incorporated into an imaging device to read the PUF. Other systems are disclosed.