Article
Optics
Qingan Ding, Xiaojuan Wang, Xudong Cheng, Huixin Liu, Liuge Du, Anhui Liang, Li Zheng, Qunying Yang
Summary: This paper proposes an improved technique of continuous shaping current-injected waveforms to suppress relaxation oscillations (ROs) in distributed feedback lasers (DFB). The signal expression of shaping current is deduced theoretically, and the specific parameters derivation of different polynomial degrees is discussed. The simulation results show that the optimized shaping signal achieves good agreement with the desired output pulse and effectively suppresses ROs at the jump edges.
Article
Optics
Xiaoyu Chen, Xin Yan, Xuenan Zhang, Fang Wang, Shuguang Li, Takenobu Suzuki, Yasutake Ohishi, Tonglei Cheng
Summary: The paper introduces a highly sensitive temperature sensor based on SPM in an in-house fabricated MOF, showing a high temperature sensitivity. The experimental results are in good agreement with theoretical simulations, providing a new approach for developing low-cost, simple structure, and high-sensitivity temperature sensors.
Article
Optics
Alejandro Rosado, Maria R. Fernandez-Ruiz, Pedro Corredera, Jose Manuel G. Tijero, Ignacio Esquivias
Summary: We have demonstrated low and continuously tunable optical frequency combs (OFCs) with line spacing in the kilohertz range. These OFCs are generated by pulsed gain-switching of commercially available semiconductor lasers emitting at around 1.55 μm. After generation, the OFCs are efficiently compressed using pseudo-random-binary-sequence phase modulation. We numerically and experimentally analyzed an OFC generated at a repetition rate of 1 GHz and identified the optimal compression conditions. The compressed comb achieved a factor of 2047 compression and exhibited a flat and broad 90 GHz spectrum consisting of more than 184,000 spectral lines, separated by 488 kHz. This significant compression factor, over 100 times larger than previously reported for gain-switching OFCs, opens up possibilities for the use of potentially integrable gain-switching OFCs in applications requiring sub-megahertz line spacing.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Dongwan Kim, Mark Harfouche, Huolei Wang, Christos T. Santis, Yaakov Vilenchik, Naresh Satyan, George Rakuljic, Amnon Yariv
Summary: This paper introduces a new semiconductor laser design that greatly reduces the absorption losses of the laser mode, resulting in improved performance. Theoretical and experimental evidence shows that this design can significantly reduce high-frequency frequency noise and achieve higher coherence.
SCIENTIFIC REPORTS
(2022)
Article
Nanoscience & Nanotechnology
Ya-Qi Qiu, Zun-Ren Lv, Hong Wang, Hao-Miao Wang, Xiao-Guang Yang, Tao Yang
Summary: The direct Si doping significantly improves the linewidth enhancement factor of 1.3-mu m InAs/GaAs quantum dot lasers, reducing the alpha(H)-factor. The increase in electron quasi-Fermi level in conduction due to Si doping leads to population inversion and accelerated capture of electrons into QDs with strengthened confinement effect.
Article
Optics
Yunlin Zhi, Lisheng Chen, Liufeng Li
Summary: This study investigates the spatial inhomogeneity of residual amplitude modulation and identifies two distinct components. The analysis reveals that the spatial inhomogeneity can be explained by the acousto-optic interaction inside the crystal. Furthermore, suppressing this spatial inhomogeneity improves the stability of residual amplitude modulation.
Article
Computer Science, Information Systems
Muhammad Hanif, Ha H. Nguyen
Summary: This article introduces a novel frequency-shift chirp spread spectrum (FSCSS) system with index modulation (IM), which can achieve much higher data rates than the conventional system. Optimal detection algorithms, both coherently and noncoherently, are presented for the proposed system, along with a low-complexity noncoherent detection algorithm to reduce computational complexity. The results show that the proposed system, while enabling much higher data rates, enjoys similar bit-error performance as that of the conventional FSCSS system.
IEEE INTERNET OF THINGS JOURNAL
(2021)
Review
Optics
Marco Piccardo, Federico Capasso
Summary: Semiconductor lasers with fast gain dynamics are known to produce frequency-modulated output, with quantum cascade lasers being ideal representatives in this class. Understanding of frequency comb regimes in these lasers has evolved from simpler arguments to more advanced theories like Kerr nonlinearity and linewidth enhancement factor. New types of frequency combs have emerged, sparking renewed interest and raising new questions in the field of quantum cascade lasers.
LASER & PHOTONICS REVIEWS
(2022)
Article
Computer Science, Information Systems
Fatma Benkhelifa, Yathreb Bouazizi, Julie A. McCann
Summary: In this article, the authors provide a comprehensive understanding of long-range (LoRa) waveform theory and quantify its orthogonality for the first time. They present LoRa waveform expressions in continuous- and discrete-time domains and analyze the orthogonality measures between different LoRa spreading factors (SFs) through cross-correlation functions. The results show that LoRa modulation is nonorthogonal, with a maximum cross-correlation of less than 26% between different SFs, and this value decreases as the difference between SFs increases. The authors also highlight the impact of different bandwidths and temporal displacement on the cross-correlation.
IEEE INTERNET OF THINGS JOURNAL
(2022)
Article
Chemistry, Analytical
Yunshan Zhang, Hongming Gu, Guolong Ma, Shijian Guan, Tao Fang, Xiangfei Chen
Summary: In this study, a novel high-speed directly modulated two-section distributed-feedback semiconductor laser based on the detuned-loading effect is proposed and simulated. The laser features a grating structure designed using the reconstruction-equivalent-chirp (REC) technique and incorporates a pi phase shift in the reflection grating to enhance the detuned-loading effect. The experimental results show that this laser offers improved modulation bandwidth and yield.
Article
Optics
Yao Zeng, Yu Huang, Pei Zhou, Penghua Mu, Nianqiang Li
Summary: We report on the manipulation of extreme events (EEs) in a slave spin-VCSEL subject to chaotic optical injection from a master spin-VCSEL. Injection parameters can regularly trigger, enhance, or suppress the relative number of EEs in the slave spin-VCSEL, where large ranges of enhanced vectorial EEs and average intensity of both vectorial and scalar EEs can be achieved with suitable parameter conditions. The probability of occurrence of EEs in the slave spin-VCSEL is associated with the injection locking regions, outside which enhanced relative number of EEs regions can be obtained and expanded with augmenting the complexity of the initial dynamic state of the slave spin-VCSEL.
Article
Engineering, Electrical & Electronic
Roman Shakhovoy, Violetta Sharoglazova, Alexander Udaltsov, Alexander Duplinskiy, Vladimir Kurochkin, Yury Kurochkin
Summary: This study explores the combined influence of chirp, jitter, and relaxation oscillations on the probability density function of interference of pulses from a gain-switched semiconductor laser. A rigorous model based on laser rate equations is developed, showing that all three effects must be considered together to properly describe interference statistics. Experimental results demonstrate perfect agreement with model predictions and are well reproduced by Monte-Carlo simulations.
IEEE JOURNAL OF QUANTUM ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Sherin Thomas, Mandeep Singh, M. N. Satyanarayan
Summary: A high sensitivity refractive index SIS waveguide with a ring resonator sensor at THz frequency is proposed in this study. The topological structure of the proposed filter is numerically simulated using the finite element method. By filling the air-filled ring resonator cavity with different refractive index materials, a maximum sensitivity of 0.509 THz/RIU is achieved. The transmission characteristics are studied by varying the structural dimensions, and it is observed that the system can be treated as a frequency selective device.
IEEE SENSORS JOURNAL
(2022)
Article
Optics
Jinming Wu, Yingchao Wan, Peng Wang, Hanwei Zhang, Xiaolin Wang, Pu Zhou, Shaojun Du, Xiaojun Xu
Summary: In order to meet the requirements of fiber laser applications under extreme temperatures, researchers designed a 1 kW fiber oscillator that can operate in a wide temperature range from -30 degrees C to 20 degrees C with low power fluctuations. This work provides guidance for the design of high-power fiber lasers operating in wide temperature ranges.
Article
Physics, Applied
Jun-Yang Sui, Jia-Hao Zou, Si-Yuan Liao, Bing-Xiang Li, Hai-Feng Zhang
Summary: In this Letter, a highly sensitive terahertz Janus sensor based on photonic spin Hall effect (PSHE) is proposed. The sensor has a Janus feature, realizing the multitasking of thickness and refractive index detection on multiple scales. It has potential applications in accelerating the research of graphene materials and providing real-time, label-free, and low-cost detection in the biomedical field.
APPLIED PHYSICS LETTERS
(2023)
