Patent ID: 7619284

Claim:
A laser diode module comprising: an electrically conductive support; a laser diode mounted on the support; an over voltage protection device mounted on the support in proximity to the laser diode; a lid coupled to each of the laser diode and the over voltage protection device; and wherein the over voltage protection device comprises: a first conductivity type semiconductor substrate including an upper surface and a lower surface; a first electrode disposed on the upper surface of the substrate; a second electrode disposed on the lower surface on the substrate; a first conductivity type doped layer adjacent the lower surface of the substrate, the first conductivity type layer having a lower resistivity than the substrate and being adjacent to the second electrode; a plurality of alternating first conductivity type regions and second conductivity type regions adjacent the upper surface of the substrate; wherein the over-voltage protection device acts as a resistor when a voltage applied to the first electrode is less than a snapback voltage, and acts as a forward-biased diode if the voltage applied to the first electrode exceeds the snapback voltage; and wherein the first electrode is disposed a distance w from an edge of the substrate closest to the laser diode, the distance w being larger than a diffusion length of holes in the first conductivity type semiconductor substrate.