Linear multi-output optical transmitter system

A transmitter for a multi-octave bandwidth fiberoptic transmission system comprising:

• a laser source which provides an optical carrier signal;
• an optical splitter that splits the optical carrier signal into a plurality of split carrier signals;
• a common module body;
• an external modulator mounted on the common module body and that modulates the split carrier signal, the external modulator having a driver signal input that receives an analog driver signal, an output that provides a modulated optical signal, and a bias input that adjusts a bias point of the external modulator;
• a modular driver mounted on the common module body that produces the driver signal, a distortion network coupled to the driver signal input that provides nonlinear predistortion of the driver signal and having a bias processor to adjust the nonlinear predistortion;
• a monitoring optical receiver coupled to the modulator output that receives a modulated optical signal;
• a first correction circuit coupled to the monitoring optical receiver that generates a first error signal indicative of even order distortion in the modulator, the first error signal being coupled to the modulator bias input to maintain bias about a bias point;
• and
• a second correction circuit coupled to the monitoring optical receiver that generates a second error signal indicative of odd order distortion in the modulator, the second error signal being coupled to the bias processor for adjusting the nonlinear distortion of the distortion network such that distortion products in the modulated optical signal are reduced.

A multi-octave bandwidth fiberoptic transmission system comprising:

• a laser having an output power of at least 50 mW and which provides an optical carrier signal;
• an optical splitter that splits the optical carrier signals into a plurality of split carrier signals;
• a housing in which the laser source and optical splitter are mounted;
• a plurality of transmitters, each transmitter mounted on the housing and comprising an external modulator mounted on a common module body and connected to the optical splitter to modulate a split carrier signal, the external modulator having a driver signal input that receives a driver signal, an output that provides a modulated optical signal;
• a modulator driver mounted on the common module body that produces the driver signal, the modulator driver having a distortion network coupled to the driver signal input that provides nonlinear pre-distortion of the driver signal;
• a monitoring optical receiver coupled to the modulator output that receives a modulated optical signal;
• a first correction circuit coupled to the monitoring optical receiver that generates a first error signal indicative of even order distortion in the modulator, the first error signal being coupled to the modulator;
• a second correction circuit coupled to the monitoring optical receiver that generates a second error signal indicative of odd order distortion in the modulator, the second error signal adjusting the nonlinear distortion of the distortion network such that distortion products in the modulated optical signal are reduced;
• and
• a multi-octave bandwidth fiberoptic transmission system connected to the transmitter within the housing.

A transmitter for a fiberoptic transmission system comprising:

• a laser source which provides an optical carrier signal having an output power of at least 200 mW;
• an external modulator that modulates the optical carrier signal, the external modulator having a driver signal input that receives an analog cable television information driver signal, an output that provides a modulated optical signal, and a DC bias input that adjusts a bias point of the external modulator;
• a modulator driver that provides the driver signal, the modulator driver comprising a distortion network coupled to the driver signal input that provides nonlinear pre-distortion of the driver signal to compensate for odd order distortion generated by the external modulator and a bias processor coupled to the distortion network for adjusting the nonlinear predistortion;
• a supervisory tone signal circuit that generates a supervisory tone signal coupled to the DC bias input having a frequency below the driver signal;
• a monitoring optical receiver coupled to the modulator output that receives the modulated optical signal and provides a monitor signal including a distorted supervisory tone signal;
• a first correction circuit coupled to the monitor signal of the monitoring optical receiver that generates a first error signal indicative of even order distortion in the modulator, the first error signal being coupled to the DC bias input of the modulator to maintain bias about a bias point;
• and
• a second correction circuit coupled to the monitor signal of the monitoring optical receiver that generates a second error signal indicative of odd order distortion in the modulator, the second error signal being coupled to the bias processor for adjusting the nonlinear distortion of the distortion network such that distortion products in the modulated optical signal are reduced.