Patent ID: 8059335

Claim:
An adjustable optical signal delay module comprising: a front-stage 3-port optical circulator receiving an input optical signal at a first port thereof and outputting said input optical signal at a second port thereof; a semiconductor optical amplifier receiving said input optical signal from said second port of said front-stage 3-port optical circulator, said semiconductor optical amplifier amplifying said input optical signal into an amplified optical signal, outputting said amplified optical signal, and generating an amplified spontaneous emission, said amplified spontaneous emission being input to said second port of said front-stage 3-port optical circulator and output from a third port thereof; a rear-stage 3-port optical circulator receiving said amplified optical signal from said semiconductor optical amplifier at a second port thereof and outputting said amplified optical signal at a third port thereof; and a feedback optical loop coupled between said third port of said front-stage 3-port optical circulator and a first port of said rear-stage 3-port optical circulator for coupling at least a portion of said amplified spontaneous emission back to said semiconductor optical amplifier by output from said second port of said rear-stage 3-port optical circulator, said feedback optical loop including (a) an optical filter receiving said amplified spontaneous emission output from said third port of said front-stage 3-port optical circulator and filtering out unnecessary light wavelengths, and (b) a variable optical attenuator receiving said filtered amplified spontaneous emission from said optical filter and outputting said filtered amplified spontaneous emission at an attenuated power level to said first port of said rear-stage 3-port optical circulator to achieve coherent population oscillation to vary a group refractive index of said semiconductor optical amplifier and thereby delay transmission of said input optical signal through said semiconductor optical amplifier.