Light-Propagation-Efficiency Evaluation Method by Using a Pinhole for Heat-Assisted Magnetic Recording

To evaluate the optical properties of a laser light through a waveguide, a pinhole layer was fabricated on an air-bearing surface of a slider. The pinhole layer consisted of a chromium thin film with a thickness of 160 nm. The pinhole (with diameter of 2 μm) was fabricated by dual-layer lift-off. The light-shielding effect of the pinhole layer was verified. The stray light outside of the pinhole was 0.18% of the light through the pinhole when the power of laser diode was 50 mW. The experimentally measured light-propagation efficiency of the waveguide was 83% of the design value.