Method and apparatus for monitoring the power level of two or more optical transmitters
Methods and apparatus for monitoring the power level of one or more optical emitters are provided. In some embodiments, optical signals from two or more optical emitters are directed at different regions of a photo detector. The photo detector may include two or more spaced contacts that are adapted to receive different contributions of photo current from each of the optical signals. By monitoring the photo currents in the two or more spaced contacts, a measure of the optical power of each of the optical signals may be determined.
1. A method for determining which of two or more optical signals experienced a power change using a photo detector, wherein the photo detector includes a photo sensitive region with two or more contacts at two or more spaced locations, the method comprising the steps of:
providing at least a portion of the two or more optical signals primarily at different areas of the photo sensitive region of the photo detector so that each of the two or more optical signals produce a different photo induced current in the two or more contacts;
detecting a measure of the photo induced current in each of the two or more contacts; and
determining which of the two or more optical signals experienced a power change from the measure of photo induced current in each of the two or more contacts.
2. A method according to claim 1 wherein the determining step determines which of the two or more optical signals experienced a power change by calculating a difference and/or a ratio of the photo induced current through the two or more contacts, and correlating the difference and/or ratio to one or more of the two or more optical signals.
3. A method according to claim 1 , further comprising the step of determining if the two or more optical signals collectively experienced a power change by detecting a measure of the total photo induced current through the two or more contacts.