Previously, when mounted in a header, light that was reflected from the top lens of the VCSEL back into the header was monitored with a Si photodiode, on which the VCSEL chip was mounted. Presently, the art has not recognized any method of monitoring the light from a VCSEL chip that is not mounted in a header. The use of a header is required in existing systems to monitor light emission.
In many applications it is desirable to know for certain that the VCSEL is in fact emitting light upon current being driven through it. The problem is to monitor this light without disturbing the lightbeam too much, and to conduct this in an affordable manner that does not require complex packaging.
The present invention provides methodology to monitor the light emission from a VCSEL without in any way obstructing and/or disturbing the output light. It also eliminates the need of mounting the VCSEL chip in a header just to monitor its output light.