Abstract

We have demonstrated experimentally flat-gain polarization-independent operation of a CW fiber optical parametric amplifier (OPA) using two orthogonal pumps, with 15 dB of gain over a 20 nm bandwidth.¹ We have also shown that it is possible to design a fiber OPA exhibiting broadband low-ripple gain spectra (e.g. 20 dB with 0.1 dB uniformity over 45 nm);² assuming that all waves were in the same linear states of polarization (SOP). However, this choice of SOPs results in a polarization-sensitive OPA. In practice, it would be desirable to have devices insensitive to the SOP of the input signal. Here we show analytically that fiber OPA’s can be rendered polarization-insensitive and still exhibit low gain-ripple, by using two orthogonal pumps. We find that, for a given gain, a fiber OPA with orthogonal pumps (OPA₁) exhibits a bandwidth which is less than a fiber OPA with pumps in the same SOP (OPA₁); we also suggest a way to avoid this difficulty.

© 2002 Optical Society of America