Method and apparatus for suppressing relative intensity noise (RIN) and improving transmission signals

An optical transmitter for transmitting signals that include information, the optical transmitter comprising:

• at least two optical sources for generating optical signals each having a substantially equal power value and each having a different wavelength;
• a phase delay element coupled to an output port of at least one of the optical sources, wherein the phase delay element delays at least one of the optical signals
• a combiner for combining the optical signals into a composite signal, wherein the composite signal has an output power value equal to the sum of the power values associated with the optical signals;
• and
• an output coupled to the combiner for transmitting the composite signal,
• wherein transmission of the composite signal provides a reduction in relative intensity noise.

A communications system for transmitting information, the communications system comprising:

• an optical transmitter, comprising:
• at least two optical sources for generating optical signals each having a substantially equal power value and each having a different wavelength;
• a phase delay element coupled to an output port of at least one of the optical sources, wherein the phase delay element delays at least one of the optical signals;
• a combiner for combining the optical signals into a composite signal, wherein the composite signal has an output power value equal to the sum of the power values associated with the optical signals;
• a modulator for modulating the composite signal;
• and
• an output port coupled to the modulator for transmitting the composite signal along a transmission medium;
• and
• an optical receiver coupled to the optical transmitter for receiving the composite signal, wherein the composite signal provides a reduction in relative intensity noise of at least 3 dB.

A method of measuring relative intensity noise (RIN), the method comprising the steps of:

• generating at least two optical signals, each having a substantially equal power value and each having a different wavelength;
• combining the optical signals into a composite signal, wherein the composite signal has an output power value equal to the sum of the power values associated with the optical signals;
• and
• measuring a level of the composite signal, such measurement associated with a value of RIN, and
• wherein the value of RIN is indicative of a reduction substantially equal to ten times logarithm of the number of optical signals.

A method in an optical transmitter for suppressing relative intensity noise (RIN), the method comprising the steps of:

• receiving an input RF signal;
• splitting the input RF signal into at least two RF signals having substantially equal information content;
• generating at least two optical signals each having a power value and differing wavelengths, the at least two optical signals each associated with one of the at least two RF signals;
• and
• combining the at least two optical signals into a composite signal, wherein the composite signal has an output power value equal to the sum of the power value of the at least two optical signals,
• wherein the composite signal provides a reduction in RIN as compared to the RIN if a single one of the optical signals, at a greater power, such as two times the power if two optical signals are provided, had been transmitted by itself.

A communications system for transmitting information, the communications system comprising:

• an optical transmitter, comprising:
• at least two optical sources for generating optical signals each having a substantially equal power value and each having a different wavelength;
• a combiner for combining the optical signals into a composite signal, wherein the composite signal has an output power value equal to the sum of the power values associated with the optical signals;
• a modulator for modulating the composite signal;
• and
• an output port coupled to the modulator for transmitting the composite signal along a transmission medium;
• and
• a splitter for splitting the composite signal into a first and second signal;
• and
• two receivers coupled to the splitter each for receiving respectively the first and second signal of the composite signal, wherein the first and second signal each provides a reduction in relative intensity noise of at least 3 dB.