Development of Integrated Small-Form-Factor Optical Pickup with Blu-ray Disc Specification

Abstract

In this study, a small-form-factor optical pickup (SFFOP), corresponding to the Blu-ray disc (BD) specifications has been developed. The developed SFFOP is composed of an integrated optical pickup and a swing-arm-type actuator. The integrated optical pickup has been developed in the form of an array using wafer-level fabrication technology. The developed SFFOP is composed of the fundamental optics which yields a numerical aperture (NA) of 0.85 and uses a blue laser diode having a short wavelength of 407 nm and a silicon optical bench, which consists of a laser diode, a photodiode and several mounts for the laser diode, an objective lens and mirrors. The micro objective lens is bonded to the lens holder on the SFFOP by an active alignment using a modified Mach–Zehnder interferometer. Also, a static focus error signal was detected to assemble a polarized holographic optical element. Through the measurement of the focus error signal with a swing-arm-type actuator, which was developed for the SFFOP, it is estimated that the developed SFFOP satisfies the BD specifications with the balance of the focus error signal below 10%.