Communications device with discriminator and wavelength division multiplexing for generating intermediate frequency signal and related methods

A communications device comprising:

• a transmitter device comprising first and second optical sources configured to generate first and second optical carrier signals at respective different first and second optical wavelengths, a first optical coupler coupled to said first and second optical sources, and a first electro-optic (EO) modulator coupled to said first optical coupler and configured to modulate a combined carrier signal comprising the first and second optical carrier signals with a radio frequency (RF) input signal;
• an optical waveguide coupled to said transmitter device;
• and
• a receiver device coupled to said optical waveguide and comprising
• a second EO modulator configured to further modulate the modulated combined carrier signal with a local oscillator (LO) signal,
• a frequency modulation-phase modulation (FM-PM) discriminator coupled to said second EO modulator and configured to convert the modulated combined carrier signal to an intensity modulated combined carrier signal based upon the LO signal, the FM-PM discriminator having a transfer function, and said first and second optical sources being configured to respectively define first and second carrier frequencies of the first and second optical carrier signals to be positioned on first and second portions of the transfer function,
• a second optical coupler coupled to said FM-PM discriminator and configured to generate first and second intensity modulated carrier signals, and
• an optical-to-electrical converter coupled to said second optical coupler and configured to generate an intermediate frequency (IF) signal based upon the first and second intensity modulated carrier signals.

A method of frequency converting a radio frequency (RF) input signal, the method comprising:

• generating first and second optical carrier signals at respective different first and second optical wavelengths;
• multiplexing the first and second optical carrier signals with a first optical coupler;
• modulating a combined carrier signal comprising the first and second optical carrier signals with the RF input signal;
• further modulating the modulated combined carrier signal with a local oscillator (LO) signal;
• converting the modulated combined carrier signal to an intensity modulated combined carrier signal based upon the LO signal and using a frequency modulation-phase modulation (FM-PM) discriminator;
• using a second optical coupler coupled to the FM-PM discriminator to generate first and second intensity modulated carrier signals;
• and
• converting the first and second intensity modulated carrier signals into an intermediate frequency (IF) electrical signal.