A thermally assisted magnetic head including a slider and a light source-unit. The slider includes a slider substrate and a magnetic head part. The light source-unit includes a laser diode and a sub-mount. The magnetic head part includes a medium-opposing surface, a light source-opposing surface and a waveguide which guides laser light from the light source-opposing surface to the medium-opposing surface. The thermally assisted magnetic head includes an optimal-structure which the following optimizing conditional expression, concerning an inlet-optical path length L1 of an inlet-interval of the waveguide, and an outlet-optical path length L2 of an outlet-interval, is satisfied,
m.sub.1L1=L2 (m.sub.1 is a natural number).

A thermally assisted magnetic head including a slider and a light source-unit. The slider includes a slider substrate and a magnetic head part. The light source-unit includes a laser diode and a sub-mount. The magnetic head part includes a medium-opposing surface, a light source-opposing surface and a waveguide which guides laser light from the light source-opposing surface to the medium-opposing surface. The thermally assisted magnetic head includes an optimal-structure which the following optimizing conditional expression, concerning an inlet-optical path length L1 of an inlet-interval of the waveguide, and an outlet-optical path length L2 of an outlet-interval, is satisfied,
m.sub.1L1=L2 (m.sub.1 is a natural number).

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. A current supplied to the laser diode for a subsequent write operation is adjusted to the updated operating current.

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. A current supplied to the laser diode for a subsequent write operation is adjusted to the updated operating current.

A frequency data transmission and encryption system comprises a transceiver module. The transceiver module is configured to receive and transmit computer-readable instructions via transmission signals comprising two distinct signals having a first frequency and a second frequency different than the first frequency. The transceiver module is further configured to convert the two distinct signals to and from a first set of computer-readable instructions based on the first frequency using a first conversion method, and a second set of computer-readable instructions based on the second frequency using a second conversion method different from the first conversion method.

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position a selected head among one or more heads proximate to a corresponding disk surface among the one or more disks; and one or more processing devices. The one or more processing devices are configured to generate a map of laser mode hop effects across the corresponding disk surface, for the selected head. The one or more processing devices are further configured to apply a laser mode hop mitigation in operating the selected head, based on the map of laser mode hop effects.

A magnetic recording method, system and apparatus are described to increasing areal density capability (ADC) for a data storage system, where in different data tracks were written with different write configurations or with different writers in a particular way that is optimized to improve areal density for a data storage device. In an aspect, the data tracks were labeled as bottom, middle or top tracks, the write order follows in a particular way among different tracks, middle and top tracks partially trim the previously written track from one side. The distance between neighboring tracks, or the percentage of track trimmed, depend on the labels they have and the drive architecture used, are different. The particular write order can be in sequential or can have a certain level of randomness as set by the drive. The write order for each operation depend on the label determined by the drive for a given drive capacity requirement. For the apparatus to enable such approach, additional alignment condition between readers, writer, heater and temperature sensor are also optimized to improve performance, areal density and reliability.

A magnetic recording method, system and apparatus are described to increasing areal density capability (ADC) for a data storage system, where in different data tracks were written with different write configurations or with different writers in a particular way that is optimized to improve areal density for a data storage device. In an aspect, the data tracks were labeled as bottom, middle or top tracks, the write order follows in a particular way among different tracks, middle and top tracks partially trim the previously written track from one side. The distance between neighboring tracks, or the percentage of track trimmed, depend on the labels they have and the drive architecture used, are different. The particular write order can be in sequential or can have a certain level of randomness as set by the drive. The write order for each operation depend on the label determined by the drive for a given drive capacity requirement. For the apparatus to enable such approach, additional alignment condition between readers, writer, heater and temperature sensor are also optimized to improve performance, areal density and reliability.

A frequency data transmission and encryption system comprises a transceiver module. The transceiver module is configured to receive and transmit computer-readable instructions via transmission signals comprising two distinct signals having a first frequency and a second frequency different than the first frequency. The transceiver module is further configured to convert the two distinct signals to and from a first set of computer-readable instructions based on the first frequency using a first conversion method, and a second set of computer-readable instructions based on the second frequency using a second conversion method different from the first conversion method.

Disclosed is an optical disk drive for wireless power transmission. The optical disk drive in an embodiment of the present invention comprises a tray on which a optical disk is to be seated; a driving unit for rotating the optical disk to be seated on the tray and reading or writing the optical disk; a wireless power transmitting module to be seated on the tray and comprising a primary coil and a transmitting circuit unit; a power supply unit for supplying power; and a controller for controlling the power supply unit to supply power to the wireless power transmitting module when determining that the wireless power transmitting module is seated on the tray