Backreflection and loss in single-fiber loopback networks

We have studied the effects of network loss and back-reflections on single-fiber loopback transmission, in which a modulator replaces the optical source at the remote terminal. Combining a broad-band source at the host terminal with an amplified modulator at the remote terminal effectively suppresses the optical beat noise, allowing data transmission at 50 Mb/s with realistic loss budgets, even in the presence of Fresnel back-reflections as large as -15 dB.