Optical return loss measurement
View Patent ↗An optical test apparatus. The test apparatus includes an optical source. A first optical switch is connected to the optical source. An attenuated responsivity test path may be selectively coupled to the first optical switch. A return loss test path may alternatively be selectively coupled to the first optical switch. A second optical switch may be selectively coupled to the attenuated responsivity test path or the return loss test path. An optical splitter is connected to the second optical switch. The optical splitter is configured to connect to a ROSA. A detector is connected to the optical splitter. The detector is configured to connect to a test meter.
1. A test apparatus comprising:
an optical source;
a first optical switch coupled to the optical source;
an attenuated responsivity test path that may be selectively coupled to the first optical switch;
a return loss test path that may be selectively coupled to the first optical switch;
a second optical switch that may be selectively coupled to the attenuated responsivity test path or the return loss test path;
an optical splitter coupled to the second optical switch wherein the optical splitter is adapted to couple to a ROSA; and
a detector coupled to the optical splitter, wherein the detector is adapted to couple to a test meter.
2. The test apparatus of claim 1 , wherein the return loss test path is an essentially un-attenuated path.
3. The test apparatus of claim 1 , wherein the optical source is an 850 nm laser.
4. The test apparatus of claim 1 , wherein the optical source is a 1310 nm laser.
5. The test apparatus of claim 1 , further comprising true RMS circuitry adapted to couple to the ROSA for creating a DC function equivalent of various AC measurements taken at the ROSA.
6. The test apparatus of claim 1 , further comprising a plurality of optical sources including the optical source.
7. The test apparatus of claim 6 , wherein the optical source is coupled to the first optical switch through a patch cord.
8. The test apparatus of claim 6 , further comprising a plurality of attenuated responsivity test paths including the attenuated responsivity test path, where each of the plurality of attenuated responsivity test paths may be selectively coupled to the first optical switch.
9. The test apparatus of claim 6 , further comprising a plurality of optical splitters including the optical splitter wherein each of the optical splitters is adapted to couple to the second optical switch.
10. The test apparatus of claim 1 , further comprising a bias tee coupled to the optical source to provide DC biasing and AC signal modulation to the optical source.
11. The test apparatus of claim 1 , wherein attenuated responsivity test path attenuates the optical signal to a level that will not cause automatic gain control circuitry of the ROSA to activate when an optical signal from the optical source is transmitted to the ROSA.
12. The test apparatus of claim 1 , wherein the first optical switch and the second optical switch are embodied as a single switch to allow for simultaneous switching.
13. A method of testing a ROSA in a single test jig assembly, the method comprising:
transmitting an optical signal through a first optical switch to an un-attenuated path, through the un-attenuated path to a second optical switch, through the second optical switch to a splitter, and through the splitter to a ROSA, wherein the first and second optical switches are in a first position that allows signals to travel through the un-attenuated path;
receiving reflected optical signals from the ROSA through the splitter at a detector; and
measuring signals at the detector caused by the receiving reflected optical signals to generate a characterization of optical return loss.
14. The method of claim 13 , wherein the method further comprises:
transmitting the optical signal through the first optical switch to an attenuated path, through the attenuated path to the second optical switch, through the second optical switch to the splitter, and through the splitter to the ROSA, wherein the first and second optical switches are in a second position that allows signals to travel through the attenuated path; and
measuring signals at the ROSA caused by the optical signal being transmitted to the ROSA.
15. The method of claim 14 , wherein the attenuated path attenuates the optical signal to a level that will not cause automatic gain control circuitry of the ROSA to activate when the optical signal is transmitted to the ROSA.
16. The method of claim 14 , wherein measuring signals at the ROSA caused by the optical signal being transmitted to the ROSA comprises converting measurements to a function of a DC equivalent of an AC signal.
17. An optical test jig comprising:
means for generating an optical signal;
means for selectively directing the optical signal into one of a plurality of optical paths wherein at least one of the paths comprises means for attenuating the optical signal and at least one of the paths is essentially un-attenuated; and
means for selectively directing the optical signal from one of the plurality of optical paths to a splitting means, wherein the splitting means is adapted to couple to a ROSA and to direct at least a portion of the optical signal into the ROSA.