The TOSA has a light source such as a laser diode, preferably of the surface-emitting type, with an inherent mode-field diameter matched without a lens to that of the optical fiber, resulting in enhanced...http://www.google.de/patents/US5631987?utm_source=gb-gplus-sharePatent US5631987 - Low cost, mode-field matched, high performance laser transmitter optical subassembly Erweiterte Patentsuche Ver