METHOD AND APPARATUS FOR MAINTAINING A PRE-DETERMINED RATIO OF A PILOT TONE POWER AND A MEAN OPTICAL OUTPUT POWER OF AN OPTICAL SIGNAL

Methods and apparatus related to maintaining a pre-determined ratio of a pil ot tone power and a total mean optical power of an optical signal are provided. The AC and DC components of an optical signal (212) having a pilot tone sign al are detected (240, 250). The pilot tone signal (224) amplitude is varied in accordance with the difference (270) between a pre-determined value (272) an d the ratio 260 of the AC and DC components. Alternatively, at least one of th e DC bias (222) and the AC bias (224) of the optical signal is varied in accordance with the difference between the pre-determined value and the rati o of the AC and DC components. In various embodiments, the DC bias only, the A C bias only, or both the AC bias and the DC bias are varied.