Special Relativity-on-a-Chip: Impact of Optical Loss in the Performance of an Optical Analogue of Thomas Effect

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We investigate the effect of the unavoidable optical loss on the recently reported optical analogue of the relativistic Thomas Effect which uses a photonic chip-based lossless All-Pass Filter (APF) circuit [J. of Mod. Optics 65.19 (2018): 2171-2178]. When the APF has loss, both its phase and amplitude responses are altered. This impacts the accuracy and operating range of the APF-based Thomas Effect analogue. To evaluate its impact on the phase output, we carry out a systematic evaluation of the phase response of the APF to explore when this Thomas Effect analogue breaks down. A lossy APF produces three dissimilar phase responses and varying dip in the amplitude response depending on the relative values of the coupling coefficient and the loss parameter. Numerical and analytical results show that APF must (i) be operated at an Over-Coupling (OC) condition (ii) with a loss parameter α ≥ 0.95 in order to have less than 1% phase error with the widest possible band coverage.