High power laser/detector unit for re-writable optical pick-up head

We propose a new on-silicon LD/PD hybrid module using a high-power LD and a silicon-PD substrate with an etched mirror for application to a small-sized re-writable optical pick-up head. A high power laser of 50 mW output is mounted on the hollow surface of a Si substrate, on which photo-diodes are formed. The emitted beam from the LD chip is turned to the vertical direction by a micromirror, which is the Si(111) crystal surface formed on the Si substrate by chemical etching. A mirror angle of 45 degrees is obtained by etching the (100) surface 9 degrees off toward the ⟨110⟩ Si substrate. By using this structure, the LD and PD substrate are aligned in two dimensions, and a small-sized unit (4.8×8.2×2.5 mm) has been obtained