A novel variable optical reflection standard to implement 16-term optical calibration

Commercial lightwave analysers use advanced normalisation techniques to implement optical calibration. As integrated optical components gain wider usage, leakage effects cannot be neglected, and hence there will be an increasing need to perform 16-term calibration. One of the main constraints at present to implement optical 16-term or even 12-term calibration is the lack of enough optical reflection standards. Given the bandwidth limitation of the line standard, it is desirable to have at least three optical reflection standards in addition to the thru standard. In this work, a variable optical reflection standard which makes use of bulk optics is proposed. The structure consists of a fibre pigtail, a lens and a mirror all separated by air. The variation in optical reflection is produced by varying the distance between the lens and the other two elements.