Precise modeling of extended sources is a central challenge in modern optical engineering, laser physics, and computational lithography. Unlike ideal point sources or completely incoherent thermal radiation sources, real-world light sources -- such as high-power laser diode arrays, superluminescent diodes (SLD), extreme ultraviolet (EUV) lithography sources, and beams transmitted through atmospheric turbulence -- typically exhibit partial spatial coherence. Traditional geometric optics based on ray tracing ignores diffraction and interference effects; while classical wave optics is accurate, the computational cost of handling four-dimensional correlation functions for partially coherent fields is enormous. To balance computational efficiency and physical accuracy, phase space optics provides a unified theoretical framework. By introducing the Wigner distribution function (WDF), we can map the light field into a joint space-time-spatial frequency domain $(\bm{r}, \bm{p})$. This description not only retains all the information of wave optics (including interference terms) but also naturally transitions to the ray description of Hamiltonian optics in the short-wavelength limit, governed by Liouville's theorem of phase space volume conservation. This report aims to establish optimal modeling methods based on phase space and Hamiltonian optics for different types of extended sources such as partially coherent light, fully coherent light, and quasi-homogeneous light. The report will derive in detail the mathematical models for each source type and provide strict criteria for the applicability of geometric optics models using mathematical tools such as the Moyal expansion and generalized Fresnel number.
A mirrored transformation optics (MTO) approach is presented to overcome the material mismatch in transformation optics. It makes good use of the reflection behavior and introduce a mirrored medium to offset the phase discontinuities. Using this approach, a high-performance planar focusing lens of transmission-type is designed, which has large concentration ratio than other focusing lens obtained by generalized Snell law. The MTO will not change any functionality of the original lens and promising potential applications in imaging and light energy harvesting.
Miniaturized and rationally assembled nanostructures exhibit extraordinarily distinct physical properties beyond their individual units. This review will focus on structured small-scale optical cavities that show unique electromagnetic near fields and collective optical coupling. By harnessing different material systems and structural designs, various light-matter interactions can be engineered, such as nanoscale lasing, nonlinear optics, exciton-polariton coupling, and energy harvesting. Key device performance of nanoscale lasers, including low power threshold, optical multiplexing, and electrical pump, will be discussed. This review will also cover emerging applications of nanoscale optical cavities in quantum engineering and topological photonics. Structured nanocavities can serve as a scalable platform for integrated photonic circuits and hybrid quantum photonic systems.
Kosta Oubrerie, Igor A. Andriyash, Ronan Lahaye
et al.
An axiparabola is a reflective aspherical optics that focuses a light beam into an extended focal line. The light intensity and group velocity profiles along the focus are adjustable through the proper design. The on-axis light velocity can be controlled, for instance, by adding spatio-temporal couplings via chromatic optics on the incoming beam. Therefore the energy deposition along the axis can be either subluminal or superluminal as required in various applications. This article first explores how the axiparabola design defines its properties in the geometric optics approximation. Then the obtained description is considered in numerical simulations for two cases of interest for laser-plasma acceleration. We show that the axiparabola can be used either to generate a plasma waveguide to overcome diffraction or for driving a dephasingless wakefield accelerator.
Acousto-optic devices utilize the overlap of acoustic and optical fields to facilitate photon-phonon interactions. For tightly confined optical and acoustic fields, such as the sub-wavelength scales achievable in integrated devices, this interaction is enhanced. Broadband operation which fully benefits from this enhancement requires light and sound to co-propagate in the same cross-section, a geometry currently lacking in the field. We introduce the `acoustic-optical multiplexer', which enables this co-linear geometry, and demonstrate through simulations a proof-of-concept design. Using suspended silicon and silica beams, the multiplexer combines two optical modes and an acoustic mode into a single, co-guided output port with low insertion loss and reflection for both optics and acoustics. The first design in its class, the multiplexer enables integrated acousto-optic devices to achieve efficient photon-phonon interactions.
The geodesic equations for optical media whose refractive indices have a non-vanishing gradient are developed. It is shown that when those media are optically isotropic, the light paths will be mull geodesics of a spatial metric that is conformally related to the metric of the ambient space. Various aspects of the optical-mechanical analogy are discussed as they relate to the geodesics of conformally related metrics. Some applications of the concepts of gradient-index optics to general relativity are examined, such as effective indices of refraction for gravitational lensing and Gordon's optical metrics for optical media that are in a state of relative motion with respect to an observer. The latter topic is approached from the standpoint of pre-metric electromagnetism.
In optical dipole traps, the excited rotational states of a molecule may experience a very different light shift than the ground state. For particles with two polarizability components (parallel and perpendicular), such as linear $^1Σ$ molecules, the differential shift can be nulled by choice of elliptical polarization. When one component of the polarization vector is $\pm i\sqrt{2}$ times the orthogonal component, the light shift for a sublevel of excited rotational states approaches that of the ground state at high optical intensity. In this case, fluctuating trap intensity need not limit coherence between ground and excited rotational states.
Nonlinear optical generation has been a well-established way to realize frequency conversion in nonlinear optics, whereas previous studies were just focusing on the scalar light fields. Here we report a concise yet efficient experiment to realize frequency conversion from vector fields to vector fields based on the vectorial nonlinear optical process, e.g., the second-harmonic generation. Our scheme is based on two cascading type-I phase-matching BBO crystals, whose fast axes are configured elaborately to be perpendicular to each other. Without loss of generality, we take the full Poincaré beams as the vectorial light fields in our experiment, and visualize the structured features of vectorial second-harmonic fields by using Stokes polarimetry. The interesting doubling effect of polarization topological index, i.e., a low-order full Poincaré beam is converted to a high-order one are demonstrated. However, polarization singularities of both C-points and L-lines are found to keep invariant during the SHG process. Our scheme can be straightforwardly generalized to other nonlinear optical effects. Our scheme can offer a deeper understanding on the interaction of vectorial light with media and may find important applications in optical imaging, optical communication and quantum information science.
We have fabricated and characterized 10,000 and 20,440 pixel Microwave Kinetic Inductance Detector (MKID) arrays for the Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer (DARKNESS) and the MKID Exoplanet Camera (MEC). These instruments are designed to sit behind adaptive optics systems with the goal of directly imaging exoplanets in a 800-1400 nm band. Previous large optical and near-IR MKID arrays were fabricated using substoichiometric titanium nitride (TiN) on a silicon substrate. These arrays, however, suffered from severe non-uniformities in the TiN critical temperature, causing resonances to shift away from their designed values and lowering usable detector yield. We have begun fabricating DARKNESS and MEC arrays using platinum silicide (PtSi) on sapphire instead of TiN. Not only do these arrays have much higher uniformity than the TiN arrays, resulting in higher pixel yields, they have demonstrated better spectral resolution than TiN MKIDs of similar design. PtSi MKIDs also do not display the hot pixel effects seen when illuminating TiN on silicon MKIDs with photons with wavelengths shorter than 1 um.
Bikshandarkoil R. Srinivasan, Suvidha G. Naik, Kiran T. Dhavskar
We argue that the L-aspartic acid nickel chloride crystal reported by the authors of the title paper (Optics Communications 2013) is actually the well-known diaqua(L-aspartato)nickel(II) hydrate crystal.
We investigate the behavior of fast light pulse propagation in an N-type Doppler-broadened 4-level atomic system using double Raman gain processes. This system displays novel and interesting results of two controllable pairs of the double gain lines profile with a control field. The detailed physics of the processes are explored having multiple controllable anomalous regions in the medium. In this set up, the system exhibits significant enhancement in the probing Gaussian pulse through the medium as compared with Ref. [L. J. Wang, A. Kuzmich, and A. Dogariu, Nature \textbf{406}, 227(2000)]. The advance time of the retrieved Gaussian pulse is always greater than the advance time studied in the above said experiment. We analyzed that the pulse propagating through the medium with larger negative group index, $7.32\times10^8$, leaves the medium almost undistorted and sooner by time $76.12 \ ms$ than the pulse which leaves the medium of Wang \emph{et al.}. The Gaussian pulse always remains almost undistorted at output due to lossless characteristic of the medium. We also underlined the ways to suppress incoherences generated by the Doppler-broadening effect in the system. The limitations of the recently developed applications require to explore mechanisms for ultimate speed of a superluminal probe light pulse. In this connection, the proposed scheme may be helpful and can be easily adjusted with the current technology.
It has been known for years how random height variations of a repeated nano-scale structure can give rise to smooth angular color variations instead of the well-known diffraction pattern experienced if no randomization is present. However, until now there has not been published any papers giving an in-depth mathematical explanation on the mechanisms behind and how to design the randomness for a given application. This paper presents a mathematical framework for analyzing these random variations -- rigorously as well as intuitively.
We propose to use transformation optics to generate a general illusion such that an arbitrary object appears to be like some other object of our choice. This is achieved by using a remote device that transforms the scattered light outside a virtual boundary into that of the object chosen for the illusion, regardless of the profile of the incident wave. This type of illusion device also enables people to see through walls. Our work extends the concept of cloaking as a special form of illusion to the wider realm of illusion optics.
G. B. Xavier, G. Vilela de Faria, G. P. Temporao
et al.
A real-time polarization control system employing two nonorthogonal reference signals multiplexed in either time or wavelength with the data signal is presented. It is shown, theoretically and experimentally, that complete control of multiple polarization states can be attained employing polarization controllers in closed-loop configuration. Experimental results show that negligible added penalties, corresponding to an average added optical Quantum Bit Error Rate of 0.044%, can be achieved with response times smaller than 10 ms, without significant introduction of noise counts in the quantum channel.