A heat-assisted magnetic recording (HAMR) disk drive has a disk with at least two independent data layers (RL1 and RL2), each data layer storing an independent data stream. At a high laser power both RL1 and RL2 are heated to above their respective Curie temperatures and a first data stream is recorded in both RL1 and RL2. At a lower laser power only upper RL2 is heated to above its Curie temperature and a second data stream is recorded only in RL2. The data layers are separated by a nonmagnetic spacer layer (SL) that prevents lower RL1 from being heated to above its Curie temperature at low laser power. The first and second data streams are typically asynchronous. Recorded data is read back from both data streams simultaneously as a composite readback signal. A joint Viterbi detector detects the asynchronous data streams simultaneously from the composite readback signal.

A heat-assisted magnetic recording (HAMR) disk has multiple independent data layers, each data layer being a continuous non-patterned layer of magnetizable material. Each data layer can store data independent and not related to the data stored in the other data layers. The data layers are separated by a nonmagnetic spacer layer (SL) and each data layer is formed of high-anisotropy (K.sub.u) material so that the coercivities of lower and upper data layers (RL1 and RL2) are greater than the magnetic write field. At a high laser power both RL1 and RL2 are heated to above their respective Curie temperatures and data is recorded in both RL1 and RL2. At low laser power only upper RL2 is heated to above its Curie temperature and data is recorded only in RL2. The SL prevents lower RL1 from being heated to above its Curie temperature at low laser power.

An apparatus and method provide for performing, using a heat-assisted magnetic recording head, multiple sequential writes to a recording medium, and recording a metric of write performance for each of the writes. The apparatus and method further provide for calculating fluctuations in the metric, detecting whether the head has a laser mode hopping problem using the metric fluctuations, and categorizing a severity of the laser mode hopping problem.

Method and apparatus for managing a data storage system that utilizes heat assisted magnetic recording (HAMR). In some embodiments, the method includes recording data to a storage medium using the HAMR system, accumulating a usage statistic indicative of actual elapsed operation of the HAMR system, and setting an indication value in a memory indicative of an estimate of remaining available elapsed operation of the HAMR system. The estimate of remaining available elapsed operation is determined in relation to the usage statistic and an estimated total elapsed operation value.

An apparatus comprises a heat-assisted magnetic recording head configured to write to and read from a magnetic recording medium. The head comprises a reader and a writer including a near-field transducer (NFT). The reader comprises a center which is laterally offset relative to a center of the writer to define a reader-writer offset (RWO) therebetween. A magnetic recording medium comprises a plurality of tracks. The plurality of tracks comprises at least one track used as a region to test for a shift in the RWO. A processor is coupled to the recording head and configured to detect the RWO shift.

A dual-slot waveguide receives energy from a coupling waveguide. The dual-slot waveguide includes first and second light propagating regions of low-index material located side-by-side in a direction normal to a light propagation direction. Inner sides of the first and second light propagating regions are separated by a first region of a high-index material. Second and third regions of the high-index material surround outer sides of the first and second light propagating regions. A near-field transducer receives portions of the energy from the first and second light propagating regions.

A write head includes a near-field transducer near a media-facing surface of the write head. The write head includes a waveguide having a core with a first side disposed proximate to the near-field transducer. The core overlaps the near-field transducer at a substrate-parallel plane. The core includes one of a step or a taper on a second side facing away from the first side. The step or the taper causes a reduced thickness of the core normal to the substrate-parallel plane. The write head includes a cladding layer that encompassing the second side of the core and that fills in the step or the taper.

A system, according to one embodiment, includes a magnetic head having: a near field transducer, an optical waveguide for illumination of the near field transducer, and an anti-reflection block positioned along the optical waveguide farther from a media facing side of the magnetic head than the near field transducer. The anti-reflection block is positioned a distance from the near field transducer to destructively interfere with light reflected away from the near field transducer. Other systems, methods, and computer program products are described in additional embodiments.

Devices that include a near field transducer (NFT); a multilayer gas barrier layer positioned on at least a portion of the NFT, the multilayer gas barrier layer including at least a first and a second sublayer, where the second gas barrier sublayer is positioned on the first gas barrier sublayer, the first gas barrier sublayer is positioned adjacent the NFT and the second gas barrier sublayer is positioned adjacent the wear resistant layer, the first and second sublayers independently have thicknesses from 0.01 nm to 5 nm; and a wear resistance layer positioned on at least a portion of the gas barrier layer.

An apparatus comprises a heat-assisted magnetic recording (HAMR) head, a sensor, and a controller. The HAMR head is configured to interact with a magnetic storage medium. The sensor is configured to produce a signal indicating the occurrence of head-medium contact. The controller is configured to receive the signal and concurrently determine from the signal if the occurrence of head-medium contact is caused by a first contact detection parameter, a second contact detection parameter, or both the first and second contact detection parameters.