Phase-coherent lightwave communications with frequency combs

Abstract

Fiber-optical networks are a crucial telecommunication infrastructure in society. Wavelength division multiplexing allows for transmitting parallel data streams over the fiber bandwidth, and coherent detection enables the use of sophisticated modulation formats and electronic compensation of signal impairments. In the future, optical frequency combs may replace multiple lasers used for the different wavelength channels. We demonstrate two novel signal processing schemes that take advantage of the broadband phase coherence of optical frequency combs. This approach allows for a more efficient estimation and compensation of optical phase noise in coherent communication systems, which can significantly simplify the signal processing or increase the transmission performance. With further advances in space division multiplexing and chip-scale frequency comb sources, these findings pave the way for compact energy-efficient optical transceivers.

Coherent optical communications using coherence-cloned Kerr soliton microcombs

“…To validate this scheme, we conduct coherent data demodulation using the precalculated ∆f CL (m) as the FOE result for each channel, and resolve the actual frequency offset error by extracting the first-order derivative of time from the data phase evolution (see Fig. 2f) [37]. As summarized in Fig.…”

“…shows that fast phase fluctuations between two-point locked microcombs mainly result from the term m • ∆φ/17 (∆φ is the residual phase noise of the phase lock loop), which linearly scales up with m and means that we can use the CPE result of one channel to predict the phase of other channels in a master-slave fashion, as sketched in Fig. 3d [5,37]. Fig.…”

“…For example, when the CPE result of channel 10 is used for channel 1, only minor BER penalty is observed in comparison with the result of independent CPE. Moreover, comparing with recent demonstrated master-slave CPE using uncorrelated carrier comb and LO comb [37], coherence-cloned DKS combs possess much longer mutual coherent time, so they should be less sensitive to phase de-coherence caused by fiber dispersion, and can potentially support longer transmission distance.…”

Parametric frequency comb generation using silicon core fiber

“…Optical frequency comb generators (OFCGs) are emerging as promising light sources for optical communications, spectroscopy, and microwave signal processing [1]. For dense wavelength division multiplexing (DWDM) communication systems, they offer many potential advantages including the elimination of optical guard bands for improved spectral efficiency [2], efficient compensation of fiber nonlinearity [3], and joint digital signal processing (DSP) that greatly reduces the DSP complexity [4]. To enable these benefits in practical systems, a frequency comb is required to have a flat spectrum within the telecom transmission window (e.g.…”

All-fibre heterogeneously-integrated frequency comb generation using silicon core fibre

“…Optical frequency combs (OFCs) generate precisely-spaced phase-coherent spectral tones and have revolutionized frequency control and metrology [1]. Over the past decade, numerous new developments have been focused on comb applications in optical communications, spectroscopy, microwave photonics, and optical-assisted signal processing [2,3,4,5]. Unlike metrology, in which broad 'over-one-octave' spectral bandwidths are the predominate requirement to enable self-referencing, communications and signal processing applications typically demand only tens of nanometers of bandwidth, but require high power, high 2 Results…”