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The unique spectral behavior exhibited by a class of non-uniform Bragg periodic structures, namely chirped and apodized fiber Bragg gratings (FBGs) influenced by parity and time reversal ($\mathcal{PT}$) symmetry, is presented. The…

Optics · Physics 2020-03-18 S. Vignesh Raja , A. Govindarajan , A. Mahalingam , M. Lakshmanan

A novel grating modulation technique for laser arrays is proposed and demonstrated. This method modifies the initial phase within each grating period, applying a total phase shift that increments in an arithmetic progression, ensuring equal…

Rapid and low-power control over the direction of a radiating light field is a major challenge in photonics and a key enabling technology for emerging sensors and free-space communication links. Current approaches based on bulky motorized…

When placed on an inclined plane, a perfect 2D disk or 3D sphere simply rolls down in a straight line under gravity. But how is the rolling affected if these shapes are irregular or random? Treating the terminal rolling speed as an order…

Classical Physics · Physics 2024-07-30 Daoyuan Qian , Yeonsu Jung , L. Mahadevan

We consider an error model for phased array with gain errors and phase errors, with errors dependent on the phase applied and the antenna index. Under this model, we propose an algorithm for measuring the errors by selectively turning on…

Signal Processing · Electrical Eng. & Systems 2021-07-21 Joyson Sebastian , Pranav Dayal , Kee-Bong Song , Walid AliAhmad

We demonstrate control of the absolute phase of an optical lattice with respect to a single trapped ion. The lattice is generated by off-resonant free-space laser beams, we actively stabilize its phase by measuring its ac-Stark shift on a…

We design the phase shifts of an intelligent reflecting surface (IRS)-assisted single-input-multiple-output communication system to minimize the outage probability (OP) and to maximize the ergodic rate. Our phase shifts design uses only…

Information Theory · Computer Science 2022-11-08 Shashank Shekhar , Athira Subhash , Tejesh Kella , Sheetal Kalyani

We propose an on-chip Si photonics optical phased array based on a serial grating design which eliminates the use of directional couplers in previous designs. It significantly reduces overall phased array size especially when the number of…

Applied Physics · Physics 2019-03-13 Lingxuan Zhang , Xiaochen Sun , Wenfu Zhang , Guoxi Wang , Ningning Feng , Wei Zhao

The generation of optical beams with multiple, mutually-coherent orbital-angular-momentum (OAM) modes using phase gratings is analyzed from the perspective of energy distribution and radial mode composition. We show that phase gratings…

Optics · Physics 2018-02-26 Jaime Cisternas , Jaime A. Anguita , Gustavo Funes

We investigate the effect of a tunable spectral filter on the dynamics of a passively mode-locked fiber laser in the anomalous dispersion regime. The results show that noise-like pulse emission evolves toward bound-state regime as the…

Phased arrays are vital in communication systems and have received significant interest in the field of optoelectronics and photonics, enabling a wide range of applications such as LiDAR, holography, wireless communication, etc. In this…

We show experimentally and theoretically that an electrically biased $200\,\mu$m multi-transverse mode Vertical-Cavity Surface-Emitting Laser can be passively mode-locked using optical feedback from a distant Resonant Saturable Absorber…

Optics · Physics 2014-07-02 M. Marconi , J. Javaloyes , S. Balle , M. Giudici

Mutual phase coherence is the most crucial factor in asynchronous optical sampling system, and its enhancement is commonly achieved by phase-locking both femtosecond lasers to a shared narrow-linewidth cavity-stabilized laser. Here we…

Optics · Physics 2020-12-30 Honglei Yang , Shengkang Zhang , Huan Zhao , Jun Ge

We report the spectral features of a phase-shifted parity and time ($\mathcal{PT}$)-symmetric fiber Bragg grating (PPTFBG) and demonstrate its functionality as a demultiplexer in the unbroken $\mathcal{PT}$-symmetric regime. The length of…

Optics · Physics 2020-08-05 S. Vignesh Raja , A. Govindarajan , A. Mahalingam , M. Lakshmanan

An Adaptive Spiral Phase Plate (ASPP) based on liquid crystal (LC) and the transmission electrode technique is theoretically and experimentally demonstrated. This ASPP design enables the generation of high-quality optical vortices with…

Optical gratings are a key component in many spectroscopy, communications, and imaging systems. While initially static elements, advances in optical materials have enabled dynamically tunable gratings to be designed. One common tuning…

Optics · Physics 2021-11-04 Jinghan He , Andre Kovach , Yunxiang Wang , William Wang , Wei Wu , Andrea M. Armani

Standard phase-stepping algorithms (PSAs) estimate the measuring phase of linear carrier temporal-fringes with respect to a linear-reference. Linear-carrier fringes are normally obtained using feedback, closed-loop, optical phase-shifting…

Signal Processing · Electrical Eng. & Systems 2019-03-27 Manuel Servin , Moises Padilla , Ivan Choque , Sotero Ordones

We developed a predictive model describing harmonic generation and intermodulation distortions in semiconductor optical amplifiers (SOAs). This model takes into account the variations of the saturation parameters along the propagation axis…

We describe and experimentally evaluate a stabilized radio-frequency transfer technique that employs optical phase sensing and optical phase actuation. This technique can be achieved by modifying existing stabilized optical frequency…

Instrumentation and Methods for Astrophysics · Physics 2018-02-14 David Gozzard , Sascha Schediwy , Richard Whitaker , Keith Grainge

This paper presents a modified rotating element electric field vector (modified REV) method to calibrate the antenna array initial condition of an optical phased array (OPA) device. The new method follows a similar sequential individual…

Applied Physics · Physics 2019-02-19 Qihao Zhang , Lingxuan Zhang , Zhongyu Li , Wei Wu , Guoxi Wang , Xiaochen Sun , Wenfu Zhang