The Ware for December 2011 was a Nichia NDV4313, or a fake of it. The NDV4313 is a 120mW, 405nm laser diode. However, there is another part running around China that seems nearly identical in spec and construction to the NDV4313, but the cost is over two orders of magnitude cheaper. I thought this was an interesting differential in pricing, so I bought some samples to investigate.

When I looked at the ware under a microscope, I was struck by its magnificent construction. If you notice from the photo, the very top chip on the stack has a clear substrate. That’s a near-perfect crystal of sapphire, onto which a thin layer of Gallium Nitride is deposited. The sapphire crystal is cleaved and polished so that the ends form the mirrors for the laser cavity. The laser itself is bonded to the monitor photodiode, which I’m guessing is made out of silicon, and then that is mounted to a gold slug which serves as the ultimate heat sink. It’s quite a work of art.

I’m guessing that no Chinese manufacture is actually “faking” a process this intricate, so most likely these diodes came from a Nichia fab, but are either rejects, relabels, or excess quantities of a legitimate, high-volume product washed through the gray market onto the shores of my lab bench.

Picking a winner was difficult as usual. A lot of correct answers; plum33 was first (and also last month’s winner), but f4eru actually mentioned Nichia in his response. Exercising fully arbitrary judgement authority, I’ll say f4eru is the winner. Congrats, email me to claim your prize!

This entry was posted on Monday, January 23rd, 2012 at 5:41 pm and is filed under Hacking. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.