Simultaneous Optical Spectral Shaping and Wavelength-to-Time Mapping for Photonic Microwave Arbitrary Waveform Generation

Photonic microwave arbitrary waveform generation (AWG) based on simultaneous optical spectral shaping and wavelength-to-time mapping in a single specially designed linearly chirped fiber Bragg grating (LCFBG) is proposed. In the proposed approach, the spectrum of a transform-limited ultrashort optical pulse is spectrally shaped, and at the same time is wavelength-to-time mapped by the LCFBG to generate a microwave pulse with a shape identical to that of the shaped optical spectrum. By designing the LCFBG to have an arbitrary reflection profile, a microwave arbitrary waveform is generated. A simple and effective technique to synthesize the LCFBG with an arbitrary reflection response is proposed. Since amplitude-only index modulation is required, the designed LCFBG can be easily fabricated. Two examples showing the generations of a chirped microwave pulse and an ultra-wideband monocycle pulse are experimentally demonstrated.