Fabrication of miniaturized polarization sensors using flip-chip bonding with atmospheric-pressure plasma activation

An ultra-small polarization sensor integrated with aluminum wire-grid polarizers has been developed for a compact optical rotary encoder. Flip-chip bonding using atmospheric-pressure plasma activation with mixed gas of Ar and H2 at a relatively low bonding temperature of 150 °C was applied to fabricate the integrated sensors. The feasibility of rotational angle measurement of a linear polarizer was demonstrated using the fabricated sensors.