We demonstrate lasing in GaAs photonic crystal waveguides with InAs quantum dots as gain medium. Structural disorder is present due to fabrication imperfection and causes multiple scat- tering of light and localization of light. Lasing modes with varying spatial extend are observed at random locations along the guide. Lasing frequencies are determined by the local structure and occur within a narrow frequency band which coincides with the slow light regime of the waveguide mode. The three-dimensional numerical simulation reveals that the main loss channel for lasing modes located away from the waveguide end is out-of-plane scattering by structural disorder.
Colloidal quantum dots (CQDs) are a promising gain material for solution-processed, wavelength-tunable lasers, with potential application in displays, communications, and biomedical devices. In this work, we combine a CQD film with an array of titanium dioxide (TiO2) nanoantennas to achieve lasing via bound states in the continuum (BICs), which are symmetry-protected cavity modes with giant quality factors. Here, the BICs arise from slab waveguide modes in the planar film, coupled to the periodic nanoantenna array. We engineer the thickness of the CQD film and size of the nanoantennas to achie…
Advance designs of random lasers towards development of miniature laser systems are in demand. We demonstrated random lasing from Rhodamine-B dye attached to polystyrene micro-spheres. Bare polystyrene spheres were used as scatterers and these provided optical feedback to the gain. Random lasing was successfully demonstrated in two different disordered environments, in binary colloidal mixture solution and in photonic glass. Incoherent feedback occurred in both the cases and single wavelength lasing were obtained. The lasing threshold in case of photonic glass was lower in comparison to binary…
In comparison with conventional lasers, topological lasers are more robust and can be immune to disorder or de-fects if lasing occurs in topologically protected states. Previously reported topological lasers were almost exclu-sively based on the first-order photonic topological insulators. Here, we show that lasing can be achieved in the zero-dimensional corner state in a second-order photonic topological insulator, which is based on Kagome wave-guide array with a rhombic configuration. If gain is present in the corner of the structure, where topological corner state resides, stable lasing in …
Dye-doped hybrid silicate/titanium nanofilms on the glass substrate in the structure of asymmetrical waveguides were studied as the laser system. The spatial and spectral features of laser oscillation of genuine and hollow waveguides were determined. Their lasing thresholds of a two-order difference of pumping power were identified. The calculated cutoff thickness for waveguides of 100 nm did not exceed their actual thickness of 300nm. The overall pattern of stimulated emission included two concurrent processes: one-mode waveguide lasing and the lateral beam emission of small divergence emanat…
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…
Line lasing in a two-dimensional lattice of orbital photonic resonators
Univ. Lille, CNRS, UMR 8523 – PhLAM – Physique des Lasers Atomes et Molécules（里尔大学，法国国家科学研究中心，UMR 8523 – 激光物理原子与分子物理实验室）；Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies（巴黎萨克雷大学，法国国家科学研究中心，纳米科学与工程中心）
Recently, optical bound states in continuum in various passive photonic crystals have been identified and similar structures incorporated with optical gain have been reported to exhibit lasing. However, no explicit control over the type of lasing BIC has been reported. In this work, we utilize all four fundamental BICs related to the lowest energy Gamma-point of a square photonic crystal lattice. We identify the associated topological charges from experimentally obtained dispersions, finite element method simulations, as well as from spherical decomposition method based on the microscopic pola…
Photonic Time Crystals (PTCs) - dielectric media with their refractive index modulated periodically in time, offer new opportunities in photonics arising from time reflections and momentum bandgaps. Here, we study the emission of light from a radiation source inside a PTC. We solve the general classical and quantum mechanical models of emission in a temporally-varying medium, and find that radiation is always exponentially amplified when associated with the momentum gap, whether initiated by a macroscopic source, an atom, or by vacuum fluctuations, drawing the amplification energy from the mod…
Analogs of spontaneous emission and lasing in photonic time crystals
Korea Advanced Institute of Science and Technology（韩国科学技术院）；University of California, Berkeley（加州大学伯克利分校）；Stanford University（斯坦福大学）；the Hong Kong University of Science and Technology（香港科技大学）；Chung-Ang University（中央大学）
We theoretically and numerically investigate the scattering behavior of a periodic parity-time (PT)-symmetric waveguide network composed of a finite number of unit cells. Specifically, we put forward rigorous and formally exact expressions for wave propagation, bi-directional reflectionless, and coherent perfect absorption and lasing (CPAL) occuring in a finite periodic optical waveguide network. Through the use of the generalized parametric space derived from observation of PT-symmetric transfer matrix, Lorentz reciprocity theorem and non-imaginary Bloch phase, we observe that when the unit c…
Topological lasers are a new class of lasers that seek to exploit the special properties of topological states of light. A typical limiting factor in their performance is the existence of non-topological states with quality factors comparable to the desired topological states. We show theoretically that by distributing uniform gain and loss on two sublattices of a two-dimensional higher-order topological insulator (HOTI) lattice, single-mode lasing based on topological corner states can be sustained over a wide range of pump strengths. This behavior stems from the parity/time-reversal breaking…
Exceptional points, with simultaneous coalescence of eigen-values and eigen-vectors, can be realized with non-Hermitian photonic systems. With the enhanced response, exceptional points have been proposed to improve the performance of photonic sensing. Recently, there are intense debate about the actual sensing advantage of exceptional points. The major concern is that intrinsic noise is also amplified at exceptional points. Here, we aim to clarify the contribution of exceptional points for photonic sensing. This is achieved by analyzing the condition to realize divergent quantum Fisher informa…
Dynamical radiation pressure effects in cavity optomechanical systems give rise to self-sustained oscillations or `phonon lasing' behavior, producing stable oscillators up to GHz frequencies in nanoscale devices. Like in photonic lasers, phonon lasing normally occurs in a single mechanical mode. We show here that phase-locked, multimode phonon lasing can be established in a multimode optomechanical system through Floquet dynamics induced by a temporally modulated laser drive. We demonstrate this concept in a suitably engineered silicon photonic nanocavity coupled to multiple GHz-frequency mech…
Microwave vortex beam lasing via photonic time crystals
Key Laboratory of advanced optoelectronic quantum architecture and measurements of Ministry of Education, Beijing Key Laboratory of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology（教育部先进光电量子架构与测量重点实验室，北京纳米光子学与超精细光电系统北京市重点实验室，物理学院，北京理工大学）；Beijing Key Laboratory of Millimeter wave and Terahertz Techniques, School of Information and Electronics, Beijing Institute of Technology（毫米波与太赫兹技术北京市重点实验室，信息与电子学院，北京理工大学）
The ability to tune the wavelength of light emission on a silicon chip is important for scalable photonic networks, distributed photonic sensor networks and next generation computer architectures. Here we demonstrate light emission in a chip-scale optomechanical device, with wide tunablity provided by a combination of radiation pressure and photothermal effects. To achieve this, we develop an optically active double-disk optomechanical system through implantation of erbium ions. We observe frequency tuning of photoluminescence in the telecommunications band with a wavelength range of 520 pm, g…
We explore absorbing open-boundary modes in non-Hermitian photonic systems. The modes have a continuum spectrum in the infinite system-size limit and can exhibit the non-Hermitian skin effect. In contrast to the conventional non-Hermitian skin modes under the fixed-end open-boundary condition, the modes concerned exhibit a strongly size-dependent spectrum that gradually converges to the non-Bloch-band dispersion. The modes correspond to the poles of the $S$ matrix, and are closely related to the lasing. We demonstrate these properties in a two-dimensional non-Hermitian photonic crystal with ga…
Universidad Autónoma de Madrid（马德里自治大学）；Università di Padova（帕多瓦大学）；Wrocław University of Science and Technology（弗罗茨瓦夫科技大学）；EPFL（洛桑联邦理工学院）；Univ Rennes, INSA Rennes, CNRS, Institut FOTON – UMR 6082（雷恩大学、雷恩国立应用科学学院、法国国家科学研究中心、FOTON研究所）；Instituto Nicolás Cabrera, Universidad Autónoma de Madrid（尼古拉斯·卡布里拉研究所，马德里自治大学）；Instituto de Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid（凝聚态物理研究所（IFIMAC），马德里自治大学）
Lasers that operate in the visible wavelength range and can be easily integrated on a chip together with photonic integrated circuits are of particular interest for biophotonic applications. We present a new class of laser sources that emit at 600 nm wavelength and can be efficiently integrated on the $\mathrm{Si}_3\mathrm{N}_4$ platform using low-cost fabrication techniques. The $\mathrm{Si}_3\mathrm{N}_4$-organic hybrid lasers are optically pumped from top without the need of a precise alignment. We investigate different laser geometries based on spiral shaped ring resonators and distributed…
We present slow-light photonic crystal waveguide designs that provide a $\times$8.6 improvement of the local density of optical states at a fully chiral point over previous designs.
We report a planar 1D photonic bandgap waveguide exhibiting four second-order exceptional points (EP2s). The interactions between the selective pairs of supported quasi-guided TE modes are modulated by spatial distribution of transverse in-homogeneous gain-loss profile.
We report on a metasurface laser emitting at the valley extremum of a multivalley energy-momentum dispersion. Such peculiar dispersion shape is obtained by hybridizing high quality factor photonic modes of different symmetry and opposite effective mass. The lasing effect takes place at high oblique angle ($\sim$20 degrees), in the telecom wavelength range ($\sim$1580 nm), on silicon substrate and operating at room temperature. Our results show the potential of multivalley dispersion for micro-laser in integrated photonic and beam-steering applications. It also opens the way to study various fe…
