Contents
2022
Volume: 20 Issue 10
16 Article(s)

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ULTRAFAST OPTICS: FUNDAMENTALS AND APPLICATIONS
Large bandgap oscillations in two-dimensional Dion–Jacobson phase perovskites caused by coherent longitudinal acoustic phonons [Invited]
Fengke Sun, Boning Wu, and Shengye Jin
Chinese Optics Letters
  • Publication Date: Oct. 12, 2022
  • Vol. 20, Issue 10, 100010 (2022)
Photoinduced excimer generation in perylene diimide dimer: effects of solvent polarity [Invited]
Guangliu Ran, Hang Wang, Yujing Song, Yahui Liu, Zhishan Bo, and Wenkai Zhang
Chinese Optics Letters
  • Publication Date: Oct. 08, 2022
  • Vol. 20, Issue 10, 100009 (2022)
Laser control strategies in full-dimensional funneling dynamics: the case of pyrazine [Invited]
Samrit Mainali, Fabien Gatti, and Osman Atabek
Motivated by the major role funneling dynamics plays in light-harvesting processes, we built some laser control strategies inspired from basic mechanisms such as interference and kicks, and applied them to the case of pyrazine. We are studying the internal conversion between the two excited states, the highest and directly reachable from the initial ground state being considered as a donor and the lowest as an acceptor. The ultimate control objective is the maximum population deposit in the otherwise dark acceptor from a two-step process: radiative excitation of the donor, followed by a conical-intersection-mediated funneling towards the acceptor. The overall idea is to first obtain the control field parameters (individual pulses leading frequency and intensity, duration, and inter-pulse time delay) for tractable reduced dimensional models basically describing the conical intersection branching space. Once these parameters are optimized, they are fixed and used in full-dimensional dynamics describing the electronic population transfer. In the case of pyrazine, the reduced model is four-dimensional, whereas the full dynamics involves 24 vibrational modes. Within experimentally achievable electromagnetic field requirements, we obtain a robust control with about 60% of the ground state population deposited in the acceptor state, while about 16% remains in the donor. Moreover, we anticipate a possible transposition to the control of even larger molecular systems, for which only a small number of normal modes are active, among all the others acting as spectators in the dynamics.
Chinese Optics Letters
  • Publication Date: Sep. 22, 2022
  • Vol. 20, Issue 10, 100007 (2022)
Sub-30 fs Yb-fiber laser source based on a hybrid cascaded nonlinear compression approach
Youming Liu, Bowen Liu, Youjian Song, and Minglie Hu
Ultrafast lasers with high repetition rate, high energy, and ultrashort pulse duration have enabled numerous applications in science and technology. One efficient route to generate such pulses is postcompression of high-power Yb-doped lasers. Here, we report on the generation of 24.5 fs pulses with an output energy of 1.6 µJ and a repetition rate of 500 kHz. The pulses are obtained by using a hybrid cascaded nonlinear compression of the pulses delivered by a Yb-based fiber chirped pulse amplification (CPA) system. In the first stage, the initial 390 fs laser pulses are compressed to 100.7 fs based on spectral broadening in three fused silica plates. In the second stage, the pulses have been shortened to sub-30 fs by means of nonlinear compression in a hollow-core fiber. Overall, we could achieve ∼16 times temporal shortening with the proposed approach. The results show that our system can effectively generate few-cycle pulses at a relatively high repetition rate and high energy, which can benefit future possible applications.
Chinese Optics Letters
  • Publication Date: Oct. 12, 2022
  • Vol. 20, Issue 10, 100006 (2022)
Rotational dephasing of the molecular alignment by centrifugal distortion [Invited]
Yunxia Huang, Guizhen Liu, and Shuwu Xu
The dephasing of molecular alignment can lead to the deformation of the alignment signal during its periodic revivals. Most studies are concentrated on the first few rotational revival periods of the molecular alignment and neglect the dephasing effect. However, study of the alignment dephasing is still of great significance for both the long-term dynamics of the molecular alignment and the dephasing itself. In this work, we theoretically demonstrate that the dephasing effect is correlated with both the rotational temperature and the rotational revival period of the molecules. The results present that the dephasing is especially significant for those molecules with long rotational revival period at high rotational temperatures. The physics behind it is explored by taking advantage of the coherence of the rotational quantum state population. This work deepens our understanding of rotational dynamics and rotational spectroscopy in molecular alignment.
Chinese Optics Letters
  • Publication Date: Aug. 30, 2022
  • Vol. 20, Issue 10, 100005 (2022)
Background-free detection of molecular chirality using a single-color beam [Invited] | On the Cover
Yuhang Chen, Xiaosong Zhu, Pengfei Lan, and Peixiang Lu
Chinese Optics Letters
  • Publication Date: Sep. 09, 2022
  • Vol. 20, Issue 10, 100004 (2022)
High spatial-resolution biological tissue imaging in the second near-infrared region via optical parametric amplification pumped by an ultrafast vortex pulse [Invited]
Xuanke Zeng, Congying Wang, Yi Cai, Qinggang Lin, Xiaowei Lu, Jiahe Lin, Xinming Yuan, Wenhua Cao, Yuexia Ai, and Shixiang Xu
Chinese Optics Letters
  • Publication Date: Aug. 28, 2022
  • Vol. 20, Issue 10, 100003 (2022)
Layer-dependent photoexcited carrier dynamics of WS2 observed using single pulse pump probe method
Lin Zhang, Jiamin Liu, Hao Jiang, Honggang Gu, and Shiyuan Liu
Understanding the ultrafast carrier dynamics and the mechanism of two-dimensional (2D) transition metal dichalcogenides (TMDs) is key to their applications in the field of optoelectronic devices. In this work, a single pulse pump probe method is introduced to detect the layer-dependent ultrafast carrier dynamics of monolayer and few-layer WS2 excited by a femtosecond pulse. Results show that the ultrafast carrier dynamics of the layered WS2 films can be divided into three stages: the fast photoexcitation phase with the characteristic time of 2–4 ps, the fast decay phase with the characteristic time of 4–20 ps, and the slow decay phase lasting several hundred picoseconds. Moreover, the layer dependency of the characteristic time of each stage has been observed, and the corresponding mechanism of free carrier dynamics has been discussed. It has been observed as well that the monolayer WS2 exhibits a unique rising time of carriers after photoexcitation. The proposed method can be expected to be an effective approach for studying the dynamics of the photoexcited carriers in 2D TMDs. Our results provide a comprehensive understanding of the photoexcited carrier dynamics of layered WS2, which is essential for its application in optoelectronics and photovoltaic devices.
Chinese Optics Letters
  • Publication Date: Aug. 03, 2022
  • Vol. 20, Issue 10, 100002 (2022)
Editorial of special issue on ultrafast optics: fundamentals and applications
[in Chinese]
Chinese Optics Letters
  • Publication Date: Oct. 14, 2022
  • Vol. 20, Issue 10, 100001 (2022)
Research Articles
Fiber Optics and Optical Communications
Portable system integrated with time comparison, ranging, and communication
Qiongqiong Zhang, Chengkai Pang, Yurong Wang, Guangyue Shen, Lei Yang, Zhaohui Li, Haiyan Huang, and Guang Wu
We demonstrate a portable system integrated with time comparison, absolute distance ranging, and optical communication (TRC) to meet the requirements of space gravitational wave detection. A 1 km free-space asynchronous two-way optical link is performed. The TRC realizes optical communication with 7.7×10-5 bit error rate with a Si avalanche photodiode single-photon detector, while the signal intensity is 1.4 photons per pulse with the background noise of 3×104 counts per second. The distance measurement uncertainty is 48.3 mm, and time comparison precision is 162.4 ps. In this TRC system, a vertical-cavity surface-emitting laser diode with a power of 9.1 µW is used, and the equivalent receiving aperture is 0.5 mm. The TRC provides a miniaturization solution for ultra-long distance inter-satellite communication, time comparison, and ranging for space gravitational wave detectors.
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 100601 (2022)
High gain E-band amplification based on the low loss Bi/P co-doped silica fiber
Jinmin Tian, Mengting Guo, Fan Wang, Chunlei Yu, Lei Zhang, Meng Wang, and Lili Hu
A home-made low loss Bi/P co-doped silica fiber was fabricated using the modified chemical vapor deposition (MCVD) technique combined with the solution doping method, where the background loss at 1550 nm was as low as 17 dB/km. We demonstrated for the first time, to the best of our knowledge, an all-fiber amplifier using the home-made Bi/P co-doped fiber achieving broadband amplification in the E-band. The amplifying performance was evaluated and optimized with different pumping patterns and fiber length. A maximum net gain at 1355 nm close to 20 dB and a minimum noise figure of 4.6 dB were obtained for the first time, to the best of our knowledge, using two 1240 nm laser diodes under bidirectional pumping with the input pump and signal powers of 870 mW and -30 dBm, respectively.
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 100602 (2022)
Integrated Optics
Experimental investigation on the unbalanced Mach–Zehnder interferometer on lithium niobate thin film
Xuerui Sun, Yinan Wu, Chuanyi Lu, Yuting Zhang, Hao Li, Shijie Liu, Yuanlin Zheng, and Xianfeng Chen
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 101301 (2022)
Microwave Photonics
Delivery of 40 Gbit/s W-band signal over 4600 m wireless distance employing advanced digital signal processing
Bowen Zhu, Yanyi Wang, Weiping Li, Feng Wang, Jiaxuan Liu, Miao Kong, and Jianjun Yu
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 103901 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Electrically reconfigurable microwave metasurfaces [Invited]
Linda Shao, Jin Zhang, Ivan D. Rukhlenko, and Weiren Zhu
Metasurfaces are ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic responses. They have attracted tremendous attention owing to their ability to freely control the propagation of electromagnetic waves. With active elements incorporated into metasurface designs, one can realize tunable and reconfigurable metadevices with functionalities controlled by external stimuli, opening up a new platform to dynamically manipulate electromagnetic waves. In this article, we review the recent progress on tunable and reconfigurable metasurfaces, focusing on their operation principles and practical applications. We describe the approaches to the engineering of reconfigurable metasurfaces categorized into different classes based on the available active materials or elements, which can offer uniform manipulations of electromagnetic waves. We further summarize the recent achievements on programmable metasurfaces with constitutional meta-atoms locally tuned by external stimuli, which can dynamically control the wavefronts of electromagnetic waves. Finally, we discuss time-modulated metasurfaces, which are meaningful to exploit the temporal dimension by applying a dynamic switching of the coding sequence. The review is concluded by our outlook on possible future directions and existing challenges in this fast developing field.
Chinese Optics Letters
  • Publication Date: Sep. 15, 2022
  • Vol. 20, Issue 10, 103601 (2022)
Broadband angular momentum cascade via a multifocal graphene vortex generator
Zhongwei Jin, Guiyuan Cao, Hongtao Wang, Han Lin, Baohua Jia, and Cheng-Wei Qiu
Light beams carrying orbital angular momentum (OAM) have inspired various advanced applications, and such abundant practical applications in turn demand complex generation and manipulation of optical vortices. Here, we propose a multifocal graphene vortex generator, which can produce broadband angular momentum cascade containing continuous integer non-diffracting vortex modes. Our device naturally embodies a continuous spiral slit vortex generator and a zone plate, which enables the generation of high-quality continuous vortex modes with deep depths of foci. Meanwhile, the generated vortex modes can be simultaneously tuned through incident wavelength and position of the focal plane. The elegant structure of the device largely improves the design efficiency and can be fabricated by laser nanofabrication in a single step. Moreover, the outstanding property of graphene may enable new possibilities in enormous practical applications, even in some harsh environments, such as aerospace.
Chinese Optics Letters
  • Publication Date: Jul. 06, 2022
  • Vol. 20, Issue 10, 103602 (2022)

About the Cover

The cover shows that a beam focused by a lens and a prism interacts with a chiral molecule. Driven by such a structured beam, the high harmonic spectrum of the chiral system will show unique even harmonics. It offers a background-free and highly sensitive detection scheme of molecular chirality with a simple and compact experimental setup. The dragon hovering over the chiral molecule is a chiral system. And it indicates that the chiral system will stand out from the achiral system and show its uniqueness.