A waveguide that includes a first cladding layer, the first cladding layer having an index of refraction, n.sub.3; a gradient index layer positioned adjacent the first cladding layer; an assist layer positioned adjacent the gradient index layer, the assist layer having an index of refraction, n.sub.2; a core layer positioned adjacent the assist layer, the core layer having an index of refraction, n.sub.1; and a second cladding layer, the second cladding layer having an index of refraction, n.sub.4, wherein n.sub.1 is greater than n.sub.2, n.sub.3, and n.sub.4; and n.sub.2 is greater than n.sub.3 and n.sub.4.

Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: write a plurality of test servo patterns using a plurality of different write settings; select one of the plurality of different write settings based on analyzing the plurality of test servo patterns for mode hop; and write a plurality of final servo patterns using the selected one of the plurality of different write settings.

A heat assisted magnetic recording (HAMR) assembly includes a slider, a laser diode and solder connections between the laser diode and the slider. The solder connections mechanically and electrically attach the laser diode to the slider. Each solder connection has a total volume per unit area (i.e., height) of less than or equal to about 15 m. The solder connections have a first intermetallic zone adjacent to the laser diode, a second intermetallic zone adjacent to the slider, and a eutectic zone of eutectic material between the first and second intermetallic zones. The eutectic zone occupies greater than or equal to about 35% of the total volume per unit area of the solder connection.

A heat assisted magnetic recording (HAMR) assembly includes a slider, a laser diode and solder connections between the laser diode and the slider. The solder connections mechanically and electrically attach the laser diode to the slider. Each solder connection has a total volume per unit area (i.e., height) of less than or equal to about 15 m. The solder connections have a first intermetallic zone adjacent to the laser diode, a second intermetallic zone adjacent to the slider, and a eutectic zone of eutectic material between the first and second intermetallic zones. The eutectic zone occupies greater than or equal to about 35% of the total volume per unit area of the solder connection.