Monolithic integrated two-wavelength laser diode for DVD-ROM/CD-ROM

摘要

We have developed a two-wavelength (650 nm and 780 nm) integrated laser diode array (TWIN-LD) for DVD system use. This is effective in reducing the number of parts in pickups, making the pickup size small and saving costs. Both of the laser diode elements have a selective buried ridge (SBR) waveguide structure with an InGaAIP common cladding layer. This structure makes the wafer process of the two-wavelength laser diode array very simple and productive. The interval between the DVD laser element and the CD laser element can be flexibly decided to meet the customer's requirements. The relative intensity noise (RIN) with a high-frequency superposition circuit is -136 dB/Hz on each side of the laser element. The newly developed TWIN-LD was applied to a new type of DVD optical pickup, and showed suitable characteristics for both DVDs and CDs.