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2. Nonlinear photonics on integrated platforms

Author

Geng Wenpu, Fang Yuxi, Wang Yingning, Bao Changjing, Liu Weiwei, Pan Zhongqi, and Yue Yang

Subjects
nonlinear photonics, integrated photonics, frequency combs, supercontinuum generation, Physics, QC1-999
Abstract

Nonlinear photonics has unveiled new avenues for applications in metrology, spectroscopy, and optical communications. Recently, there has been a surge of interest in integrated platforms, attributed to their fundamental benefits, including compatibility with complementary metal-oxide semiconductor (CMOS) processes, reduced power consumption, compactness, and cost-effectiveness. This paper provides a comprehensive review of the key nonlinear effects and material properties utilized in integrated platforms. It discusses the applications and significant achievements in supercontinuum generation, a key nonlinear phenomenon. Additionally, the evolution of chip-based optical frequency combs is reviewed, highlighting recent pivotal works across four main categories. The paper also examines the recent advances in on-chip switching, computing, signal processing, microwave generation, and quantum applications. Finally, it provides perspectives on the development and challenges of nonlinear photonics in integrated platforms, offering insights into future directions for this rapidly evolving field.

Published
2024
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4. Using a Complex Optical Orbital-Angular-Momentum Spectrum to Measure Object Parameters: A Spatial Domain Approach

Author

Xie, Guodong, Song, Haoqian, Zhao, Zhe, Milione, Giovanni, Ren, Yongxiong, Liu, Cong, Zhang, Runzhou, Bao, Changjing, Li, Long, Wang, Zhe, Pang, Kai, Starodubov, Dmitry, Tur, Moshe, and Willner, Alan E.

Subjects
Physics - Optics
Abstract

Light beams can be characterized by their complex spatial profiles in both intensity and phase. Analogous to time signals, which can be decomposed into multiple orthogonal frequency functions, a light beam can also be decomposed into a set of spatial modes that are taken from an orthogonal basis. Such a decomposition can provide a tool for spatial spectrum analysis, which may allow the stable, accurate and robust extraction of physical object information that may not be readily achievable using traditional approaches. As an example, we measure the opening angle of an object using the complex spectrum of orbital angular momentum (OAM) modes as the basis, achieving a more than 15 dB signal-to-noise ratio. We find that the dip (i.e., notch) positions of the OAM intensity spectrum are dependent on an object's opening angle but independent of the object opening's angular orientation, whereas the slope of the OAM phase spectrum is dependent on the object opening's orientation but independent on the opening angle., Comment: 19 pages, 6 figures

Published
2017
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5. Orthogonally Polarized Kerr Frequency Combs

Author

Bao, Changjing, Liao, Peicheng, Kordts, Arne, Zhang, Lin, Matsko, Andrey, Karpov, Maxim, Pfeiffer, Martin H. P., Xie, Guodong, Cao, Yinwen, Yan, Yan, Almaiman, Ahmed, Zhao, Zhe, Mohajerin-Ariaei, Amirhossein, Fallahpour, Ahmad, Alishahi, Fatemeh, Tur, Moshe, Maleki, Lute, Kippenberg, Tobias J., and Willner, Alan E.

Subjects
Physics - Optics
Abstract

Kerr optical frequency combs with multi-gigahertz spacing have previously been demonstrated in chip-scale microresonators, with potential applications in coherent communication, spectroscopy, arbitrary waveform generation, and radio frequency photonic oscillators. In general, the harmonics of a frequency comb are identically polarized in a single microresonator. In this work, we report that one comb in one polarization is generated by an orthogonally polarized soliton comb and two low-noise, orthogonally polarized combs interact with each other and exist simultaneously in a single microresonator. The second comb generation is attributed to the strong cross-phase modulation with the orthogonally polarized soliton comb and the high peak power of the intracavity soliton pulse. Experimental results show that a second frequency comb is excited even when a continuous wave light as a "seed"-with power as low as 0.1 mW-is input, while its own power level is below the threshold of comb generation. Moreover, the second comb has a concave envelope, which is different from the sech2 envelope of the soliton comb. This is due to the frequency mismatch between the harmonics and the resonant frequency. We also find that the repetition rates of these two combs coincide, although two orthogonal resonant modes are characterized by different free spectral ranges.

Published
2017

7. Spatial Phase and Amplitude Structuring of Beams Using a Combination of Multiple Orthogonal Spatial Functions with Complex Coefficients

Author

Xie, Guodong, Liu, Cong, Li, Long, Ren, Yongxiong, Zhao, Zhe, Yan, Yan, Ahmed, Nisar, Wang, Zhe, Willner, Asher J., Bao, Changjing, Cao, Yinwen, Ziyadi, Morteza, Almaiman, Ahmed, Ashrafi, Solyman, Tur, Moshe, and Willner, Alan E.

Subjects
Physics - Optics
Abstract

Analogous to time signals that can be composed of multiple frequency functions, we use uniquely structured orthogonal spatial modes to create different beam shapes. We tailor the spatial structure by judiciously choosing a weighted combination of multiple modal states within an orthogonal basis set, and we can tunably create beam phase and intensity "shapes" that are not otherwise readily achievable. As an example shape, we use a series of orbital-angular-momentum (OAM) functions with adjustable complex weights to create a reconfigurable spatial region of higher localized power as compared to traditional beam combining. We simulate a structured beam created by coherently combining several orthogonal OAM beams with different complex weights, and we achieve a >10X localized power density enhancement with 19 beams. Additionally, we can create unique shapes by passing a single beam through a specially designed phase and intensity mask that contains the combination of multiple OAM functions each with complex weights. Using this approach, we experimentally demonstrate a ~2.5X localized power density increase when utilizing 9 functions., Comment: 15 pages, 5 figures

Published
2016

22. Recent Progress of Supercontinuum Generation in Nanophotonic Waveguides.

Author

Fang, Yuxi, Bao, Changjing, Li, Si‐Ao, Wang, Zhi, Geng, Wenpu, Wang, Yingning, Han, Xu, Jiang, Jicong, Zhang, Weigang, Pan, Zhongqi, Li, Zhaohui, and Yue, Yang

Subjects
*SUPERCONTINUUM generation, *COMPLEMENTARY metal oxide semiconductors, *SILICON alloys, *WAVEGUIDES, *OPTICAL waveguides, *SILICON nitride, *LITHIUM niobate
Abstract

Supercontinuum (SC) has opened up possibilities for numerous applications in optical communications, signal processing, metrology, and spectroscopy. Supercontinuum generation (SCG) in the integrated nonlinear platforms has attracted much interest recently, due to its fundamental advantages in terms of complementary metal oxide semiconductor compatibility, low power consumption, compact size, and cost‐effectiveness. In this paper, the latest progress on various types of nanophotonic waveguides for SCG is reviewed. The material properties of silicon, germanium, silicon–germanium alloy, silicon nitride, silica, chalcogenide, III–V materials, lithium niobate, and other materials, which are used as nonlinear media for SCG are discussed. The wavelength‐dependent nonlinear Kerr index, material, and nonlinear loss of the waveguides are taken into account. This review mainly focuses on the SCG resulting from the cubic χ(3) nonlinearity processes pumped by the femtosecond pulse. The recent representative SCG works based on the integrated optical waveguides are summarized, and further classified according to the dispersion characteristics. Furthermore, different types of spectra broadening mechanisms in details according to the classifications are analyzed. Perspectives on the SC spectral coverage, the realization of various dispersion curves, and the novel materials, which are the key aspects of the SCG in nanophotonic waveguides are provided. [ABSTRACT FROM AUTHOR]

Published
2023
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32. Multiparameter Monitoring of PAM4 Signals Using Deep Learning

Author

Li, Si-Ao, primary, Liu, Yuanpeng, additional, Zhang, Yiwen, additional, Zhao, Wenqian, additional, Shi, Tongying, additional, Han, Xiao, additional, Djordjevic, Ivan B., additional, Ren, Yongxiong, additional, Bao, Changjing, additional, Pan, Zhongqi, additional, and Yue, Yang, additional

Published
2022
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40. Dual Concentric-Ring-Core Fiber With Four Zero-Dispersion Wavelengths for Beyond Three-Octave OAM Supercontinuum Generation

Author

Geng, Wenpu, Fang, Yuxi, Wang, Yingning, Wang, Zhi, Liu, Yan-ge, Zhang, Lin, Bao, Changjing, Ren, Yongxiong, Pan, Zhongqi, and Yue, Yang

Abstract

Orbital angular momentum (OAM) beams, featuring with unique spatial field distributions, have been extensively investigated and applied into a wide range of fields. In most applications, OAM beams covering a certain frequency band are usually required, and supercontinuum (SC) generation is a feasible method to provide broadband OAM source. As a short pulse is incident into a specially designed optical fiber with flat dispersion over broad bandwidth, a broadband SC could be generated along propagation due to the nonlinear spectral broadening. In this work, we propose a dual concentric-ring-core fiber design to achieve near-zero and flat dispersion profile over 3007-nm wavelength range with four zero-dispersion wavelengths for the OAM mode. The precise position of the zero-dispersion wavelengths can be tailored by varying the structural variables and the germanium-doped concentration of the silica-based fiber. The performance of the spectral broadening in terms of flatness and bandwidth is investigated under different input pulse and propagation conditions. Simulation results depict that the OAM3,1 mode supercontinuum spectrum can achieve beyond three-octave spanning from 445 to 3942 nm at −40 dB level by pumping a 50-fs 600-kW Gaussian pulse at the central wavelength of 1900 nm into a 2-mm designed fiber. By further optimizing the proposed fiber structure for the OAM1,1 mode with <60 ps/(nm·km) dispersion variation over a 3210-nm bandwidth, the generated supercontinuum can cover nearly three octaves.

Published
2023
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41. Highly Dispersive Optical Fiber for Orbital Angular Momentum Modes

Author

Geng, Wenpu, Fang, Yuxi, Wang, Yingning, Bao, Changjing, Zhang, Hao, Ren, Yongxiong, Pan, Zhongqi, and Yue, Yang

Abstract

Orbital angular momentum (OAM) modes, featured by the unique properties of the helical phase front and annular intensity profile, have shown enormous potential for a wide range of applications. Optical fibers with ring-shape profile have been experimentally proven for supporting stable OAM beam propagation. In most instances, managing the chromatic dispersion is of vital importance in a variety of optical fiber systems. In this paper, we summarize optical fibers with concentric ring cores for extremely dispersive OAM modes. The properties of the OAM mode in double ring-core fiber are presented, including the effective refractive index, effective mode area, power integral ratio, chromatic dispersion, and loss. Photonic crystal fiber and triple ring-core fiber, which share the same operation principle for dispersive OAM modes as the one in the dual-ring fiber, are also briefly introduced.

Published
2023
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42. Dispersion Compensating Ring Fibre in the C-Band for OAM Mode

Author

Zhao, Wenqian, primary, Han, Xu, additional, Geng, Wenpu, additional, Wang, Yingning, additional, Fang, Yuxi, additional, Bao, Changjing, additional, Wang, Zhi, additional, Liu, Yan-Ge, additional, Ren, Yongxiong, additional, Pan, Zhongqi, additional, and Yue, Yang, additional

Published
2021
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