System and method for removing far field limitations in microwave photonic arbitrary waveform generators

摘要

A photonic waveform generator and a method of generating an electrical waveform based on a photonic signal are disclosed. The generator includes an input port for receiving an optical signal, a pulse shaper coupled to the input port and configured to Fourier transform the optical signal and apply a pre-distort waveform onto optical spectrum of the optical signal, a dispersive pulse stretcher coupled to the pulse shaper, an optical-to-electrical converter coupled to the dispersive pulse stretcher, and an output port coupled to the optical-to-electrical converter, the pre-distortion removes distortion of the electrical signal that exists in the absence of the pre-distortion caused by violation of far field limitation between the optical signal and the electrical signal.

主权项

1. A photonic waveform generator, comprising:
an input port for receiving an optical signal; a pulse shaper coupled to the input port and configured to Fourier transform the optical signal and apply a pre-distortion waveform onto optical spectrum of the optical signal resulting in a shaped optical signal having both optical amplitude and optical phase spectral shaping; a dispersive pulse stretcher coupled to the pulse shaper and configured to provide a frequency dependent delay which disperses the shaped optical signal; an optical-to-electrical converter coupled to the dispersive pulse stretcher and configured to convert an optical input corresponding to the dispersed shaped optical signal to an electrical output; and an output port coupled to the optical-to-electrical converter and configured to output an electrical signal corresponding to the electrical output, the pre-distortion waveform of the transformed optical signal removes distortion of the electrical signal that exists in the absence of the pre-distortion waveform caused by violation of far field limitation between the optical signal and the electrical signal, where the shaped optical signal having both optical amplitude and optical phase spectral shaping is given by Ain(ω), where Ain(ω) is based on a Fourier transform of the time domain representation an(t) of the shaped optical signal, whereai⁢⁢n⁡(t)=aFTM⁡(t)⁢exp(j⁢⁢t22⁢ψ2), where aFTM(t) is calculated so that the |AFTM(ω=−t/ψ2|2 is equal to the desired electrical signal waveform, where AFTM(ω) is the Fourier transform of aFTM(t), andψ2=-∂2⁢β⁡(ω)∂ω2⁢L, where ψ2 is a group delay dispersion of the dispersive pulse stretcher and β(ω) is a propagation constant in a medium in which the optical signal travels, the medium having length L.