Optical Comb Sources and High-Resolution Optical Filtering for Measurement of Photodiode Harmonic Distortion

Abstract

Abstract-In this work we preset a new technique for measurement of harmonic distortion in microwave photodiodes. Our technique combines optical combs and high-resolution optical filtering to provide a pure optical two-tone excitation of the photodiode. Our technique removes the challenges presented by laser frequency drift and modulator bias control by utilizing a single laser and phase-modulation to synthesize the optical combs. We demonstrate our technique through measurement of the harmonic distortion generated in a commercial InGaAs photodiode and compare our results with those obtained via phase-locked laser measurements. We show that this technique provides essentially equivalent measurement fidelity to phase-locked laser techniques while offering decreased system complexity. We additionally provide a general discussion of the limits of nonlinearity measurements performed using optical heterodyne techniques.

Programmable electromagnetic pulse shaping

“…In recent work, an optical comb-based waveform generator was utilized to probe the nonlinearity of microwave photodiodes [21], [22]. In this demonstration, the waveform generator comprises two optical comb sources with slightly offset line spacings of f 1 and f 2 = f 1 + Δf which are passed through a high-resolution FT pulse shaper.…”

“…In contrast to a laser heterodyne system, however, both combs are derived from the same laser source Measured RF power spectra (see [14]). [21], [22]). thereby eliminating the effects of optical frequency drift.…”

“…In [22] CW signals generated using this technique are used to probe the nonlinearity of microwave photodiodes near 1 GHz. This work demonstrated that the spectral purity of optical comb-based microwave sources is more than sufficient to characterize harmonic distortion levels in state-of-the-art microwave photodiodes.…”

“…This work demonstrated that the spectral purity of optical comb-based microwave sources is more than sufficient to characterize harmonic distortion levels in state-of-the-art microwave photodiodes. The interested reader should consult [21] and [22] for more details.…”

Gain and coherence collapse condition for a laser diode with optoelectronic feedback using Volterra series

“…Feedback is used for steady data transmission in commercial communication systems [66]. For high resolution two-tone separation and two-tone signal quality, an optical filter/feedback system is used [67]. Feedback methods are also used for setting the quality factor, gain, and loss [68].…”