| 摘要 |
A bi-directional polarization independent optical isolator and monitor/amplifier system simultaneously transmits two separate signal rays in opposite forward directions while simultaneously suppressing backward transmission of each signal ray in its respective reverse direction. Both of the counter-propagating signal rays are amplified within an optical gain element. The separate signal rays include either two wavelength bands completely separated in wavelength or two sets of wavelengths, each of a plurality of wavelengths, such that wavelengths of the two signal rays are interspersed in alternating fashion. The bi-directional polarization independent optical isolator portion of the system comprises a birefringent polarization separation element, a reciprocal optical rotation element, a lens, a reflective element, a lens, a non-reciprocal optical rotation element, and a birefringent polarization combining element. The reflective element comprises either a mirror/waveplate assembly (which comprises a red reflector, a quarter-wave plate, and a blue reflector) or a non-linear interferometer. An assembly of four parallel optical fibers or ports is also optically coupled to the isolator such that the input and output of each pass through the isolator is coupled to a pair of diagonally disposed fibers or ports. The four fibers or ports may be configured such that either single-stage bi-directional isolation is accomplished for each of two fiber transmission lines or double stage bi-directional isolation is accomplished on a single fiber transmission line. The monitor/amplifier portion of the system is comprised of a separate assembly of four optical ports together with a second lens, two reciprocal optical rotation elements and a non-reciprocal optical rotation element. The monitor/amplifier provides for monitoring of optical power of both signal rays both before its input into and output from the optical gain element and provides for injection of two separate counter-propagating pump laser beams into the optical gain element and optical isolation of each of said pump beams from the output of the other laser.
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