分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Soliton microcombs have shown great potential in a variety of applications ranging from chip scale frequency metrology to optical communications and photonic data center, in which light coupling among cavity transverse modes, termed as intermode interactions, are long-existing and usually give rise to localized impacts on the soliton state. Of particular interest are whispering gallery mode based crystalline resonators, which with dense mode families, potentially feature interactions of all kind. While effects of narrow-band interactions such as spectral power spikes have been well recognized in crystalline resonators, that of broadband interactions remains unexplored. Here, we demonstrate microcombs with broadband and dispersive intermode interactions, in home-developed magnesium fluoride microresonators with an intrinsic $\mathbf{Q}$-factor approaching 10 billion.In addition to conventional soliton comb generation in the single mode pumping scheme, comb states with broadband spectral tailoring effect have been observed, via an intermode pumping scheme.Remarkably, footprints of both constructive and destructive interference on the comb spectrum have been observed, which as confirmed by simulations, are connected to the dispersive effects of the coupled mode family.Our results not only contribute to the understanding of dissipative soliton dynamics in multi-mode or coupled resonator systems, but also extend the access to stable soliton combs in crystalline microresonators where mode control and dispersion engineering are usually challenging.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Di Xia
Zelin Yang
Pingyang Zeng
Bin Zhang
Jiayue Wu
Zifu Wang
Jiaxin Zhao
Mingqi Gao
Yufei Huang
Jianteng Huang
Liyang Luo
Dong Liu
Shuixian Yang
Hairun Guo
Zhaohui Li
摘要： Photonic integrated microcombs have enabled advanced applications in optical communication, microwave synthesis, and optical metrology, which in nature unveil an optical dissipative soliton pattern under cavity-enhanced nonlinear processes. The most decisive factor of microcombs lies in the photonic material platforms, where materials with high nonlinearity and in capacity of high-quality chip integration are highly demanded. In this work, we present a home-developed chalcogenide glasses-Ge25Sb10S65 (GeSbS) for the nonlinear photonic integration and for the dissipative soliton microcomb generation. Compared with the current integrated nonlinear platforms, the GeSbS features wider transparency from the visible to 11 um region, stronger nonlinearity, and lower thermo-refractive coefficient, and is CMOS compatible in fabrication. In this platform, we achieve chip-integrated optical microresonators with a quality (Q) factor above 2 x 10^6, and carry out lithographically controlled dispersion engineering. In particular, we demonstrate that both a bright soliton-based microcomb and a dark-pulsed comb are generated in a single microresonator, in its separated fundamental polarized mode families under different dispersion regimes. The overall pumping power is on the ten-milliwatt level, determined by both the high Q-factor and the high material nonlinearity of the microresonator. Our results may contribute to the field of nonlinear photonics with an alternative material platform for highly compact and high-intensity nonlinear interactions, while on the application aspect, contribute to the development of soliton microcombs at low operation power, which is potentially required for monolithically integrated optical frequency combs.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yufei Huang
Di Xia
Pingyang Zeng
Jiaxin Zhao
Zelin Yang
Suwan Sun
Liyang Luo
Guiying Hu
Dong Liu
Yufei Li
Hairun Guo
Bin Zhang
Zhaohui Li
摘要： Chalcogenide glass (ChG) is an attractive material for integrated nonlinear photonics due to its wide transparency and high nonlinearity, and its capability of being directly deposited and patterned on Silicon wafer substrates. It has a singular Raman effect among amorphous materials. Yet, the Raman lasing performance in high quality and chip integrated ChG microresonators remains unexplored. Here, we demonstrate an engineered Raman lasing dynamic based on home developed photonic integrated high-Q ChG microresonators. With a quality factor above 10^6, we achieve the record-low lasing threshold 3.25 mW among integrated planar photonic platforms. Both the single-mode Raman lasers and a broadband Raman-Kerr comb are observed and characterized, which is dependent on the dispersion of our flexible photonic platform and engineered via tuning the waveguide geometric size. The tunability of such a chipscale Raman laser is also demonstrated through tuning the pump wavelength and tuning the operating temperature on the chip. This allows for the access of single-mode lasing at arbitrary wavelengths in the range 1615-1755 nm. Our results may contribute to the understanding of rich Raman and Kerr nonlinear interactions in dissipative and nonlinear microresonators, and on application aspect, may pave a way to chip-scale efficient Raman lasers that is highly desired in spectroscopic applications in the infrared.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Dissipative structures are the result of spontaneous symmetry breaking in a dynamic open system, which is induced by either the nonlinear effect or loss fluctuations. While optical temporal dissipative solitons in nonlinear Kerr cavities has been widely studied, they are operated in a red-detuned regime that is non-trivial to access. Here, we demonstrate an emergent dissipative soliton state in optical cavities in the presence of loss fluctuations, which is accessible by self-evolution of the system and is operated in resonance. We numerically investigate both the effect of loss modulation and the effect of saturable absorption, based on a standard dissipative and Kerr-nonlinear microresonator model, and observe stable soliton states in a close-to-zero detuning region. The self-starting soliton state working in resonance is potentially of wide interest, which would not only ease the operation for ultrafast temporal soliton generation, but also imply a high conversion efficiency for soliton micro-combs.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Zhichao Ye
Haiyan Jia
Zhangjun Huang
Chen Shen
Jinbao Long
Baoqi Shi
Yi-Han Luo
Lan Gao
Wei Sun
Hairun Guo
Jijun He
Junqiu Liu
摘要： The foundry development of integrated photonics has revolutionized today's optical interconnect and datacenters. Over the last decade, we have witnessed the rising of silicon nitride (Si$_3$N$_4$) integrated photonics, which is currently transferring from laboratory research to foundry manufacturing. The development and transition are triggered by the ultimate need of low optical loss offered by Si$_3$N$_4$, which is beyond the reach of silicon and III-V semiconductors. Combined with modest Kerr nonlinearity, tight optical confinement and dispersion engineering, Si$_3$N$_4$ has today become the leading platform for linear and Kerr nonlinear photonics, and has enabled chip-scale lasers featuring ultralow noise on par with table-top fiber lasers. However, so far all the reported fabrication processes of tight-confinement, dispersion-engineered Si$_3$N$_4$ photonic integrated circuit (PIC) with optical loss down to few dB/m have only been developed on 4-inch or smaller wafers. Yet, to transfer these processes to established CMOS foundries that typically operate 6-inch or even larger wafers, challenges remain. In this work, we demonstrate the first foundry-standard fabrication process of Si$_3$N$_4$ PIC with only 2.6 dB/m loss, thickness above 800 nm, and near 100% fabrication yield on 6-inch wafers. Such thick and ultralow-loss Si$_3$N$_4$ PIC enables low-threshold generation of soliton frequency combs. Merging with advanced heterogeneous integration, active ultralow-loss Si$_3$N$_4$ integrated photonics could pave an avenue to addressing future demands in our increasingly information-driven society.
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