The NLFM waveform resulting from a tunable integrated optical ring resonator is simulated and compared with the well
known tan-FM waveform. The metrics of interest are the first sidelobe levels and FWHM times of the autocorrelation,
as these directly relate to the long-range performance and fine range resolution of a LADAR system, and should ideally
be as small as possible. Through simulation, the sidelobe level of the autocorrelation of an NLFM waveform generated
by a series of tunable integrated optical ring resonators is shown to be lower than the autocorrelation sidelobe level of an
equivalent optimized tan-FM waveform with an equal FWHM time. A proof of concept experiment employing
thermally tunable Silicon Nitride integrated optical ring resonator is shown to generate NLFM chirped waveforms with
frequency chirps of 28 kHz.
A fast, non-interferometric measurement technique that allows the frequency-dependent delay and amplitude responses to be measured is presented. For a single amplitude and relative phase measurement at a fixed optical wavelength, the measurement time is on the order of a microsecond. RF modulation up to 2.7 GHz can be accommodated. A modified technique using frequency modulation is described to overcome non-idealities in the phase measurement. Results are presented for a fiber Bragg grating and an acetylene gas cell with swept-wavelength laser tuning at a rate of 40 nm/s.