Wide dynamic range optical link using DSSC linearizer

A wide dynamic range optical link comprising

• a laser source for producing a lightwave carrier output at a predetermined power level and wavelength;
• a double sideband suppressed carrier optical modulator having the lightwave carrier as a first input and an RF information-bearing signal as a second input, said modulator producing a suppressed carrier modulated signal output having a characteristic modulation index, said double sideband suppressed carrier optical modulator comprising
• a signal splitter for dividing the lightwave carrier into primary and secondary carriers,
• a Mach-Zehnder optical modulator into which the primary carrier is input and modulated by the RF information bearing signal, producing a modulated signal comprising information sidebands and a primary carrier component,
• a feedback controlled phase shifter in which phase of the secondary carrier is shifted 180 degrees from phase of the primary carrier,
• a signal combiner into which are input the modulated signal and the phase shifted secondary carrier, the combination of said signals causing the controlled suppression of the carrier component in the output of the signal combiner, and
• a feedback loop for controlling the phase shifter comprising an optical detector for detecting the amplitude of the carrier component in the suppressed carrier signal and means for providing a control signal derived from the detected carrier amplitude to the phase shifter;
• and
• a linear optical amplifier for increasing the modulation index of the modulated signal output from the suppressed-carrier modulator, said linear optical amplifier comprising a pumped diode laser illuminating a rare earth doped optical fiber segment, input wavelength division multiplexers and output wavelength division demultiplexers for enabling the suppressed carrier modulated signal to enter and exit the amplifier fiber segment, and an optical termination connected to the second end of the rare earth doped optical fiber, the output wavelength division demultiplexer being connected to an optical fiber medium for transmission of the modulated signal.

A wide dynamic range optical link comprising

• a laser source for producing a lightwave carrier output at a predetermined power level and wavelength;
• a double sideband suppressed carrier optical modulator having the lightwave carrier as a first input and an RF information-bearing signal as a second input, said double sideband suppressed carrier modulator comprising a signal splitter for dividing the lightwave carrier into primary and secondary carriers, a Mach-Zehnder optical modulator into which the primary carrier is input and modulated by the RF information signal to produce a modulated signal comprising information sidebands and a primary carrier component, a feedback controlled phase shifter in which phase of the secondary carrier is shifted 180 degrees from phase of the primary carrier, a signal combiner into which are input the modulated signal and the phase shifted secondary carrier, the combination of said signals causing the controlled suppression of the carrier component in the output of the signal combiner, and a feedback loop for controlling the phase shifter comprising an optical detector for detecting the amplitude of the carrier component in the suppressed carrier signal, and a means for providing a control signal derived from the detected carrier amplitude to the phase shifter,
• said double sideband suppressed carrier modulator producing a suppressed carrier modulated signal output having a characteristic modulation index;
• and
• a linear optical amplifier for increasing the modulation index of the modulated signal output from the suppressed-carrier modulator, said linear optical amplifier comprising a pumped diode laser illuminating a rare earth doped optical fiber segment, input wavelength division multiplexers and output wavelength division demultiplexers for enabling the suppressed carrier modulated signal to enter and exit the amplifier fiber segment, an optical termination connected to the second end of the rare earth doped optical fiber, the output wavelength division demultiplexer being connected to an optical fiber medium for transmission of the modulated signal.