Applications of optical microcombs

Abstract

Optical microcombs represent a new paradigm for generating laser frequency combs based on compact chip-scale devices, which have underpinned many modern technological advances for both fundamental science and industrial applications. Along with the surge in activity related to optical microcombs in the past decade, their applications have also experienced rapid progress: not only in traditional fields such as frequency synthesis, signal processing, and optical communications but also in new interdisciplinary fields spanning the frontiers of light detection and ranging (LiDAR), astronomical detection, neuromorphic computing, and quantum optics. This paper reviews the applications of optical microcombs. First, an overview of the devices and methods for generating optical microcombs is provided, which are categorized into material platforms, device architectures, soliton classes, and driving mechanisms. Second, the broad applications of optical microcombs are systematically reviewed, which are categorized into microwave photonics, optical communications, precision measurements, neuromorphic computing, and quantum optics. Finally, the current challenges and future perspectives are discussed.

On the Accuracy of Microcomb-based Photonic RF Transversal Signal Processors

“…In principle, for a tap number approaching infinity (M →∞), any arbitrary impulse response for different signal processing functions can be realized by applying corresponding tap coefficients to each wavelength channel. However, for a practical system with a finite M, there are deviations between its processing output and the ideal results that decrease with increasing M. At the same time, the sampling rate determines the free spectral range (FSR) of the RF spectral response of the transversal signal processor, which is given by [20]…”

“…In contrast, optical microcombs [27,28], which are laser frequency combs (LFCs) generated by micro-resonators with high quality (Q) factors, show distinctive advantages by simultaneously providing large numbers of wavelength channels based on a single compact device. In addition, compared to LFCs generated by modelocked fiber lasers [29,30], optical microcombs have large comb spacings enabled by the small volume of the microresonators, which yield wide Nyquist bands between different wavelength channels that allow for large operation bandwidths for the transversal signal processors [19,20]. Recently, a variety of signal processing functions have been demonstrated using microcomb-based photonic RF transversal signal processors, including not only basic processing functions such as differentiation [16,31], integration [17], and Hilbert transform [15,18], but also more complex functions such as phase encoding [32], arbitrary waveform generation [33,34], and computing in optical neural networks [35][36][37].…”

“…In the past two decades, a variety of signal processing functions have been realized based on different types of optical devices and systems, such as fiber gratings [5,6], semiconductor optical amplifiers (SOAs) together with optical filters [7,8], meta-surfaces in free-space optical systems [9][10][11], RF photonic systems with integrated micro-resonators or subwavelength gratings serving as optical processing modules [3,[12][13][14], and photonic RF transversal signal processing systems [15][16][17][18]. Amongst them, photonic RF transversal signal processing systems show competitive advantages in achieving highly reconfigurable signal processing based on a single system [19,20], which are attractive for meeting different processing requirements in practical applications.…”

A review of telecommunications applications of X(3) optical non-linearities of 2D materials

“…FWM is a fundamental third-order nonlinear optical process that has been widely used for all optical signal generation and processing, including wavelength conversion [98,[123][124][125][126][127][128][129][130][131][132][133], optical frequency comb generation [134][135][136][137][138][139][140][141][142][143][144][145], optical sampling [146,147], quantum entanglement [29, 30 148-157], and many other processes. The conversion efficiency (CE) of FWM is mainly determined by the third-order Kerr nonlinearity of the material that makes of the device.…”

Review of c⁽³⁾Optical Nonlinearities in 2D Materials for Telecommunications Applications

“…where λ is the central wavelength, D is the integral of the optical fields over the material regions, Sz is the time-averaged Poynting vector calculated using mode solving software, FWM is a fundamental third-order nonlinear optical process that has been widely used for all optical signal generation and processing, including wavelength conversion [98,[123][124][125][126][127][128][129][130][131][132][133], optical frequency comb generation [134][135][136][137][138][139][140][141][142][143][144][145], optical sampling [146,147],…”