Research

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11 pages, 29780 KiB

Open AccessArticle

Soliton Microcomb on Chip Integrated Si₃N₄ Microresonators with Power Amplification in Erbium-Doped Optical Mono-Core Fiber

by Xinpeng Chen, Suwan Sun, Weizhu Ji, Xingxing Ding, You Gao, Tuo Liu, Jianxiang Wen, Hairun Guo and Tingyun Wang

Micromachines 2022, 13(12), 2125; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13122125 - 30 Nov 2022

Viewed by 2113

Abstract

Soliton microcombs, offering large mode spacing and broad bandwidth, have enabled a variety of advanced applications, particularly for telecommunications, photonic data center, and optical computation. Yet, the absolute power of microcombs remains insufficient, such that optical power amplification is always required. Here, we [...] Read more.

Soliton microcombs, offering large mode spacing and broad bandwidth, have enabled a variety of advanced applications, particularly for telecommunications, photonic data center, and optical computation. Yet, the absolute power of microcombs remains insufficient, such that optical power amplification is always required. Here, we demonstrate a combined technique to access power-sufficient optical microcombs, with a photonic-integrated soliton microcomb and home-developed erbium-doped gain fiber. The soliton microcomb is generated in an integrated

{Si}_{3} N_{4}

microresonator chip, which serves as a full-wave probing signal for power amplification. After the amplification, more than 40 comb modes, with 115-GHz spacing, reach the onset power level of >−10 dBm, which is readily available for parallel telecommunications , among other applications. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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11 pages, 1972 KiB

Open AccessArticle

Demonstration of Ultra-High-Q Silicon Microring Resonators for Nonlinear Integrated Photonics

by Desheng Zeng, Qiang Liu, Chenyang Mei, Hongwei Li, Qingzhong Huang and Xinliang Zhang

Micromachines 2022, 13(7), 1155; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13071155 - 21 Jul 2022

Cited by 5 | Viewed by 2544

Abstract

A reflowing photoresist and oxidation smoothing process is used to fabricate ultra-high-Q silicon microring resonators based on multimode rib waveguides. Over a wide range of wavelengths near 1550 nm, the average Q-factor of a ring with 1.2-μm-wide waveguides reaches up to 1.17 × [...] Read more.

A reflowing photoresist and oxidation smoothing process is used to fabricate ultra-high-Q silicon microring resonators based on multimode rib waveguides. Over a wide range of wavelengths near 1550 nm, the average Q-factor of a ring with 1.2-μm-wide waveguides reaches up to 1.17 × 10⁶, with a waveguide loss of approximately 0.28 dB/cm. For a resonator with 1.5-μm-wide waveguides, the average Q-factor reaches 1.20 × 10⁶, and the waveguide loss is 0.27 dB/cm. Moreover, we theoretically and experimentally show that a reduction in the waveguide loss significantly improves the conversion efficiency of four-wave mixing. A high four-wave mixing conversion efficiency of −17.0 dB is achieved at a pump power of 6.50 dBm. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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9 pages, 6366 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Topological Nanophotonic Wavelength Router Based on Topology Optimization

by Hongyi Yuan, Zhouhui Liu, Maoliang Wei, Hongtao Lin, Xiaoyong Hu and Cuicui Lu

Micromachines 2021, 12(12), 1506; https://0-doi-org.brum.beds.ac.uk/10.3390/mi12121506 - 30 Nov 2021

Cited by 7 | Viewed by 3858

Abstract

The topological nanophotonic wavelength router, which can steer light with different wavelength signals into different topological channels, plays a key role in optical information processing. However, no effective method has been found to realize such a topological nanophotonic device. Here, an on-chip topological [...] Read more.

The topological nanophotonic wavelength router, which can steer light with different wavelength signals into different topological channels, plays a key role in optical information processing. However, no effective method has been found to realize such a topological nanophotonic device. Here, an on-chip topological nanophotonic wavelength router working in an optical telecom band is designed based on a topology optimization algorithm and experimentally demonstrated. Valley photonic crystal is used to provide a topological state in the optical telecom band. The measured topological wavelength router has narrow signal peaks and is easy for integration. This work offers an efficient scheme for the realization of topological devices and lays a foundation for the future application of topological photonics. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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11 pages, 3697 KiB

Open AccessArticle

Design of Broadband Flat Optical Frequency Comb Based on Cascaded Sign-Alternated Dispersion Tellurite Microstructure Fiber

by Guocheng Huang, Meicheng Fu, Junli Qi, Jinghan Pan, Wenjun Yi and Xiujian Li

Micromachines 2021, 12(10), 1252; https://0-doi-org.brum.beds.ac.uk/10.3390/mi12101252 - 15 Oct 2021

Cited by 1 | Viewed by 1382

Abstract

We designed a tellurite microstructure fiber (TMF) and proposed a broadband optical frequency comb generation scheme that was based on electro-optical modulation and cascaded sign-alternated dispersion TMF (CSAD-TMF). In addition, the influence of different nonlinear effects, the ultrashort pulse evolution in the CSAD-TMF [...] Read more.

We designed a tellurite microstructure fiber (TMF) and proposed a broadband optical frequency comb generation scheme that was based on electro-optical modulation and cascaded sign-alternated dispersion TMF (CSAD-TMF). In addition, the influence of different nonlinear effects, the ultrashort pulse evolution in the CSAD-TMF with the anomalous dispersion (AD) zones and the normal dispersion (ND) zones were analyzed based on the generalized nonlinear Schrodinger equations (GNLSE) modelling. According to the simulations, when the input seed comb had a repetition rate of 20 GHz and had an input pulse peak power of 30 W, the generation scheme could generate optical frequency combs with a 6 dB spectral bandwidth spanning over 170 nm centered at 1550 nm. Furthermore, the generated combs showed good coherence in performance over the whole 6 dB spectral bandwidth. The highly coherent optical frequency combs can be used as high-repetition-rate, multi-wavelength light sources for various integrated microwave photonics and ultrafast optical signal processing applications. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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6 pages, 1823 KiB

Open AccessArticle

Observation of Ultrashort Laser Pulse Evolution in a Silicon Photonic Crystal Waveguide

by Xiaochun Wang, Jiali Liao, Jinghan Pan, Heng Yang and Xiujian Li

Micromachines 2021, 12(8), 911; https://0-doi-org.brum.beds.ac.uk/10.3390/mi12080911 - 30 Jul 2021

Cited by 1 | Viewed by 1357

Abstract

Using the sum frequency generation cross-correlation frequency-resolved optical gating (SFG-XFROG) measurement setup, we observed the soliton evolution of low energy pulse in an Si photonic crystal waveguide, and it exhibited the pulse broadening, blue shift, and evident pulse acceleration. The soliton evolution was [...] Read more.

Using the sum frequency generation cross-correlation frequency-resolved optical gating (SFG-XFROG) measurement setup, we observed the soliton evolution of low energy pulse in an Si photonic crystal waveguide, and it exhibited the pulse broadening, blue shift, and evident pulse acceleration. The soliton evolution was also investigated by nonlinear Schrödinger equation (NLSE) modelling simulation, and the simulated results agreed well with the experimental measurements. The effects of waveguide length on the pulse evolution were analyzed; the results showed that the pulse width changed periodically with increasing waveguide length. The results further the understanding of the ultra-fast nonlinear dynamics of solitons in silicon waveguides, and are helpful to soliton-based functional elements on CMOS-compatible platforms. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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7 pages, 2949 KiB

Open AccessArticle

Folded Heterogeneous Silicon and Lithium Niobate Mach–Zehnder Modulators with Low Drive Voltage

by Shihao Sun, Mengyue Xu, Mingbo He, Shengqian Gao, Xian Zhang, Lidan Zhou, Lin Liu, Siyuan Yu and Xinlun Cai

Micromachines 2021, 12(7), 823; https://0-doi-org.brum.beds.ac.uk/10.3390/mi12070823 - 14 Jul 2021

Cited by 18 | Viewed by 3781

Abstract

Optical modulators were, are, and will continue to be the underpinning devices for optical transceivers at all levels of the optical networks. Recently, heterogeneously integrated silicon and lithium niobate (Si/LN) optical modulators have demonstrated attractive overall performance in terms of optical loss, drive [...] Read more.

Optical modulators were, are, and will continue to be the underpinning devices for optical transceivers at all levels of the optical networks. Recently, heterogeneously integrated silicon and lithium niobate (Si/LN) optical modulators have demonstrated attractive overall performance in terms of optical loss, drive voltage, and modulation bandwidth. However, due to the moderate Pockels coefficient of lithium niobate, the device length of the Si/LN modulator is still relatively long for low-drive-voltage operation. Here, we report a folded Si/LN Mach–Zehnder modulator consisting of meandering optical waveguides and meandering microwave transmission lines, whose device length is approximately two-fifths of the unfolded counterpart while maintaining the overall performance. The present devices feature a low half-wave voltage of 1.24 V, support data rates up to 128 gigabits per second, and show a device length of less than 9 mm. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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Review

Jump to: Research

45 pages, 5710 KiB

Open AccessReview

AlGaAs Nonlinear Integrated Photonics

by Ehsan Mobini, Daniel H. G. Espinosa, Kaustubh Vyas and Ksenia Dolgaleva

Micromachines 2022, 13(7), 991; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13070991 - 24 Jun 2022

Cited by 15 | Viewed by 4021

Abstract

Practical applications implementing integrated photonic circuits can benefit from nonlinear optical functionalities such as wavelength conversion, all-optical signal processing, and frequency-comb generation, among others. Numerous nonlinear waveguide platforms have been explored for these roles; the group of materials capable of combining both passive [...] Read more.

Practical applications implementing integrated photonic circuits can benefit from nonlinear optical functionalities such as wavelength conversion, all-optical signal processing, and frequency-comb generation, among others. Numerous nonlinear waveguide platforms have been explored for these roles; the group of materials capable of combining both passive and active functionalities monolithically on the same chip is III–V semiconductors. AlGaAs is the most studied III–V nonlinear waveguide platform to date; it exhibits both second- and third-order optical nonlinearity and can be used for a wide range of integrated nonlinear photonic devices. In this review, we conduct an extensive overview of various AlGaAs nonlinear waveguide platforms and geometries, their nonlinear optical performances, as well as the measured values and wavelength dependencies of their effective nonlinear coefficients. Furthermore, we highlight the state-of-the-art achievements in the field, among which are efficient tunable wavelength converters, on-chip frequency-comb generation, and ultra-broadband on-chip supercontinuum generation. Moreover, we overview the applications in development where AlGaAs nonlinear functional devices aspire to be the game-changers. Among such applications, there is all-optical signal processing in optical communication networks and integrated quantum photonic circuits. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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26 pages, 5794 KiB

Open AccessReview

Femtosecond Laser-Fabricated Photonic Chips for Optical Communications: A Review

by Chengkun Cai and Jian Wang

Micromachines 2022, 13(4), 630; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13040630 - 16 Apr 2022

Cited by 7 | Viewed by 3704

Abstract

Integrated optics, having the unique properties of small size, low loss, high integration, and high scalability, is attracting considerable attention and has found many applications in optical communications, fulfilling the requirements for the ever-growing information rate and complexity in modern optical communication systems. [...] Read more.

Integrated optics, having the unique properties of small size, low loss, high integration, and high scalability, is attracting considerable attention and has found many applications in optical communications, fulfilling the requirements for the ever-growing information rate and complexity in modern optical communication systems. Femtosecond laser fabrication is an acknowledged technique for producing integrated photonic devices with unique features, such as three-dimensional fabrication geometry, rapid prototyping, and single-step fabrication. Thus, plenty of femtosecond laser-fabricated on-chip devices have been manufactured to realize various optical communication functions, such as laser generation, laser amplification, laser modulation, frequency conversion, multi-dimensional multiplexing, and photonic wire bonding. In this paper, we review some of the most relevant research progress in femtosecond laser-fabricated photonic chips for optical communications, which may break new ground in this area. First, the basic principle of femtosecond laser fabrication and different types of laser-inscribed waveguides are briefly introduced. The devices are organized into two categories: active devices and passive devices. In the former category, waveguide lasers, amplifiers, electric-optic modulators, and frequency converters are reviewed, while in the latter, polarization multiplexers, mode multiplexers, and fan-in/fan-out devices are discussed. Later, photonic wire bonding is also introduced. Finally, conclusions and prospects in this field are also discussed. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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30 pages, 1640 KiB

Open AccessReview

Spectral Interferometry with Frequency Combs

by Krishna Twayana, Israel Rebolledo-Salgado, Ekaterina Deriushkina, Jochen Schröder, Magnus Karlsson and Victor Torres-Company

Micromachines 2022, 13(4), 614; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13040614 - 14 Apr 2022

Cited by 2 | Viewed by 3670

Abstract

In this review paper, we provide an overview of the state of the art in linear interferometric techniques using laser frequency comb sources. Diverse techniques including Fourier transform spectroscopy, linear spectral interferometry and swept-wavelength interferometry are covered in detail. The unique features brought [...] Read more.

In this review paper, we provide an overview of the state of the art in linear interferometric techniques using laser frequency comb sources. Diverse techniques including Fourier transform spectroscopy, linear spectral interferometry and swept-wavelength interferometry are covered in detail. The unique features brought by laser frequency comb sources are shown, and specific applications highlighted in molecular spectroscopy, optical coherence tomography and the characterization of photonic integrated devices and components. Finally, the possibilities enabled by advances in chip scale swept sources and frequency combs are discussed. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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25 pages, 120720 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Progress in Silicon-Based Slow-Light Electro-Optic Modulators

by Changhao Han, Ming Jin, Yuansheng Tao, Bitao Shen and Xingjun Wang

Micromachines 2022, 13(3), 400; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13030400 - 28 Feb 2022

Cited by 9 | Viewed by 4652

Abstract

As an important optoelectronic integration platform, silicon photonics has achieved significant progress in recent years, demonstrating the advantages on low power consumption, low cost, and complementary metal–oxide–semiconductor (CMOS) compatibility. Among the different silicon photonics devices, the silicon electro-optic modulator is a key active [...] Read more.

As an important optoelectronic integration platform, silicon photonics has achieved significant progress in recent years, demonstrating the advantages on low power consumption, low cost, and complementary metal–oxide–semiconductor (CMOS) compatibility. Among the different silicon photonics devices, the silicon electro-optic modulator is a key active component to implement the conversion of electric signal to optical signal. However, conventional silicon Mach–Zehnder modulators and silicon micro-ring modulators both have their own limitations, which will limit their use in future systems. For example, the conventional silicon Mach–Zehnder modulators are hindered by large footprint, while the silicon micro-ring modulators have narrow optical bandwidth and high temperature sensitivity. Therefore, developing a new structure for silicon modulators to improve the performance is a crucial research direction in silicon photonics. Meanwhile, slow-light effect is an important physical phenomenon that can reduce the group velocity of light. Applying slow-light effect on silicon modulators through photonics crystal and waveguide grating structures is an attractive research point, especially in the aspect of reducing the device footprint. In this paper, we review the recent progress of silicon-based slow-light electro-optic modulators towards future communication requirements. Beginning from the principle of slow-light effect, we summarize the research of silicon photonic crystal modulators and silicon waveguide grating modulators in detail. Simultaneously, the experimental results of representative silicon slow-light modulators are compared and analyzed. Finally, we discuss the existing challenges and development directions of silicon-based slow-light electro-optic modulators for the practical applications. Full article

(This article belongs to the Special Issue Photonic Chips for Optical Communications)

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