Optical signal denoising through temporal passive amplification

Abstract

Mitigating the stochastic noise introduced during the generation, transmission, and detection of temporal optical waveforms remains a significant challenge across many applications, including radio-frequency photonics, light-based telecommunications, spectroscopy, etc. The problem is particularly difficult for the weak-intensity signals often found in practice. Active amplification worsens the signal-to-noise ratio, whereas noise mitigation based on optical bandpass filtering attenuates further the waveform of interest. Additionally, current optical filtering approaches are not optimal for signal bandwidths narrower than just a few GHz. We propose a versatile concept for simultaneous amplification and noise mitigation of temporal waveforms, here successfully demonstrated on optical signals with bandwidths spanning several orders of magnitude, from the kHz to GHz scale. The concept is based on lossless temporal sampling of the incoming coherent waveform through Talbot processing. By reaching high gain factors ( > 100 ), we show the recovery of ultra-weak optical signals, with power levels below the detector threshold, additionally buried under a much stronger noise background. The method is inherently self-tracking, a capability demonstrated by simultaneously denoising four data signals in a dense wavelength division multiplexing scheme.

All‐Optical Parametric‐Assisted Oversampling and Decimation for Signal Denoising Amplification

“…For instance, in previous demonstrations of Talbot amplifiers, the product (sampling rate)×(passive amplification factor) has been limited to ≈38 GHz. [37] In this work, we present a novel photonic signal processing concept, which is here applied to the simultaneous denoising and amplification of arbitrary optical signals. We refer to this method as Parametric-assisted Oversampling and Decimation (POD).…”

“…Later, the concept was extended to continuous non‐periodic signals in a system that is known as temporal Talbot array illuminator (T‐TAI). [ 35–37 ] Here, similar phase‐only operations are used to focus the coherent content of the input signal into periodic short pulses outlining an amplified copy of the signal, whereas the stochastic (non‐coherent) noise remains nearly unaltered. [ 37 ] For their practical implementation, Talbot‐based amplifiers need to realize a sophisticated temporal phase modulation in discrete short time‐bins of length $$T/q$$, with q being the target amplification factor and T being the output sampling period.…”

High-capacity free-space optical link in the midinfrared thermal atmospheric windows using unipolar quantum devices

“…The first generation of unipolar modulators based on the transition between weak and strong light–matter coupling regimes demonstrated a 750-MHz bandwidth limited by drift transport velocity, with a 10% modulation depth 34 . Yet, communication systems require devices with a large signal-to-noise ratio (SNR) on top of a multi-GHz bandwidth, in order to accommodate bit-level separations, even if progress has recently been made to tackle strong background noise issues 35 …”

“…34 Yet, communication systems require devices with a large signal-to-noise ratio (SNR) on top of a multi-GHz bandwidth, in order to accommodate bit-level separations, even if progress has recently been made to tackle strong background noise issues. 35 In this article, we take the promising results recently obtained 36 with midinfrared Stark-effect 37 modulators one step further by extending the transmission range to 31 m with a Herriott cell. The high-power signal at the output of the modulator advocates for even longer distances of propagation that would require outside facilities and telescopes for beam shaping.…”

Noise Signal Recognition and Noise Reduction Algorithm of Ships

“…Crockett et al [2] put forward a method for denoising narrow band optical signal at the kHz and MHz levels. It has been proved that the method is robust to the potential drift of signal processing center frequency, superior to traditional narrow band filter.…”