In-line forward/backward fiber-optic signal analyzer

An apparatus comprising:

• a source of a seed-signal laser beam;
• a signal-input optical fiber optically coupled to the source to propagate the seed-signal laser beam in a forward-traveling direction in a core of the input optical fiber;
• a signal-output optical gain fiber;
• a forward-tap output fiber;
• a backward-tap output fiber;
• a beam splitter optically coupled to the input fiber, the signal-output gain fiber, the forward-tap fiber, and the backward tap fiber, and configured to split the forward-traveling seed-signal laser beam from the core of input optical fiber into a plurality of portions including a first portion having a majority of the forward-traveling seed-signal laser beam directed into a core of the signal-output optical gain fiber and a second portion having a minority of the forward-traveling seed-signal laser beam directed into the forward-tap output fiber and to direct at least a portion of any backward-propagating light from the signal-output gain fiber into the backward-tap output fiber;
• and
• an analyzer functionally coupled to the second portion of the forward-traveling seed-signal laser beam and at least the portion of a backward-traveling laser beam and that generates an analysis signal.

An apparatus comprising:

• means for generating a seed-signal laser beam;
• input optical-fiber core means for propagating the seed-signal laser beam in a forward-traveling direction;
• means for splitting the forward-traveling seed-signal laser beam from the input optical-fiber core means into a plurality of portions including a first portion having majority of the forward-traveling seed-signal laser beam and a second portion having a minority of the forward-traveling seed-signal laser beam;
• first output optical-fiber gain means for propagating and amplifying a first forward laser signal output beam, second output optical fiber means for propagating a first forward laser beam tap signal, and third output optical fiber means for propagating a first backward-traveling laser beam tap signal;
• means for directing the first portion of the forward-traveling seed-signal laser beam into the first output optical-fiber gain means;
• means for directing the second portion of the forward-traveling seed-signal laser beam into the second output optical-fiber means;
• means for directing at least a first portion of a backward-traveling laser beam from the first output optical fiber gain means into the third output optical-fiber means;
• and
• means for analyzing the first forward seed-signal laser beam tap signal and means for analyzing at least the first portion of a backward-traveling laser beam.