Experimental Demonstration of a Low Optical Loss AlN Heatsink for Reduction of HAMR NFT Self-Heating

Aluminum nitride (AlN) is a promising dielectric heatsinking material candidate for heat-assisted magnetic recording (HAMR) light delivery systems, offering both low optical loss and high thermal conductivity under appropriate deposition conditions. This study presents an optical heating platform designed to locally raise the temperature of near-field transducers (NFTs) for examining heatsinking. We study Au NFTs on AlN waveguides, with the same device configuration on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {SiN}}_{x} $ </tex-math></inline-formula> waveguides for comparison. The effectiveness of the AlN heatsink is confirmed by comparing the power tolerance of the NFTs (as measured by deformation), using <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {SiN}}_{x} $ </tex-math></inline-formula> versus AlN as the underlayer. Notably, Au NFTs on AlN could tolerate 1.5–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.5\times $ </tex-math></inline-formula> more incident power compared with those on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {SiN}}_{x} $ </tex-math></inline-formula> as the underlayer, demonstrating the heatsinking capability of AlN.