Time Lens-Based Optical Fourier Transformation for All-Optical Signal Processing of Spectrally-Efficient Data

Scalable WDM phase regeneration in a single phase-sensitive amplifier through optical time lenses

“…As the Fourier transform of a temporal waveform is its spectrum, the time-lens-based OFT can convert the temporal profile of the input signal to its spectral profile and vice versa. In particular, these OFT variations can be realized by merely reordering the time-lens and dispersive media arrangement 26 . Additionally, the OFTs are fully coherent, preserving amplitude and phase of the processed signals, and thus guarantee transparency to the data modulation format, and have previously been demonstrated to achieve serial-to-WDM conversion of a 16 QAM 320-GBd signal 27 .…”

“…Two different OFTs are used in the proposed regeneration scheme. The first one (OFT 1) with a chirp-dispersion (K-D) configuration is used for WDM (parallel) to serial conversion 26 . It is based on a quadratic phase-modulation stage ( δϕ = Kt 2 /2) with chirp rate K , followed by a dispersive medium with D  =  β 2 L (where β 2 is the second-order dispersion and L is the fibre length), which satisfies the condition K  = 1/ D .…”

“…The obtained OOK WDM signal is converted to a 160-GBd serial signal by the first OFT ( S2 ). The quadratic phase modulation is implemented by a FWM process in a 500 m HNLF using linearly chirped rectangular pump pulses 26 . The idler electric field E i ( t ) generated by FWM of pump E p ( t ) and signal E s ( t ) is given by , where η is the efficiency factor of the FWM process, determined by the properties of the HNLF.…”

“…The size of the GI depends on the bandwidth of the serial signal and the dispersion value of the dispersive medium. The GI can potentially be reduced to below 5% by using a “complete” OFT scheme with a K-D-K configuration, rendering it fully independent of the serial signal bandwidth and the dispersive medium 26 .…”

Characterization of Chirped Pump Four-Wave Mixing in Nonlinear Fibers using only Continuous-Wave-Lasers

“…The time lens [1], based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF) [2], using chirped, flat-top pump pulses to, e.g., perform the optical Fourier transformation [3], is a versatile tool for advanced optical signal processing [4]. However, thus far no systematic characterization procedures for the optimization of such time lenses have been demonstrated.…”