Patent ID: 7345811

Claim:
An apparatus to amplify optical signals comprising: a multimode fiber to receive an input optical signal from an optical signal source and form a signal path through said apparatus; at least one input signal sensor to measure strength of said input optical signal along said signal path; a multimode amplification unit subsequent said at least one input signal sensor to receive said input optical signal from said fiber and to amplify and filter said input optical signal, wherein said amplification unit includes a plurality of amplification stages successively coupled to each other, and wherein each stage includes: a gain element to amplify an optical signal received by that stage; and a noise filter coupled to said gain element to filter noise from said optical signal amplified by said gain element; a limiter coupled to said amplification unit to receive and attenuate said amplified optical signal from a final one of said amplification stages to produce an attenuated signal; a band filter coupled to said limiter to filter said attenuated signal and provide a resulting amplified signal within a desired band; at least one output signal sensor to measure strength of said resulting amplified signal; and a microcontroller to collectively control said limiter, said amplification unit and said band filter in accordance with at least said measured signal strengths to control amplification of said input optical signal.