Search query: Topological insulator laser

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abstract: Topological photonics has recently been proved a robust framework for manipulating light. Active topological photonic systems, in particular, enable richer fundamental physics by employing nonlinear light matter interactions, thereby opening a new landscape for applications such as topological lasing. Here we report an all dielectric topological insulator laser scheme based on semiconductor cavities formed by topologically distinct Kagome photonic crystals. The proposed planar semiconductor Kagome lattice allows broadband edge states below the light line due to photonic valley hall effect in telecommunication region, which provides a new route to retrieve nontrivial photonic topology and to develop integrated topological systems for robust light generation and transport.
author_names: Yongkang Gong

Stephan Wong

Anthony J Bennett

Diana L Huffaker

Sang Soon Oh
title: Topological Insulator Laser Using Valley Hall Photonic Crystals
year: 2020

abstract: We propose a system that exploits the fundamental features of topological photonics and synthetic dimensions to force many semiconductor laser resonators to synchronize, mutually lock, and under suitable modulation emit a train of transform limited mode locked pulses. These lasers exploit the Floquet topological edge states in a 1D array of ring resonators, which corresponds to a 2D topological system with one spatial dimension and one synthetic frequency dimension. We show that the lasing state of the multielement laser system possesses the distinct characteristics of spatial topological edge states while exhibiting topologically protected transport. The topological synthetic space edge mode imposes a constant phase difference between the multifrequency modes on the edges, and together with modulation of the individual elements forces the ensemble of resonators to mode lock and emit short pulses, robust to disorder in the multiresonator system. Our results offer a proof of concept mechanism to actively mode lock a laser diode array of many lasing elements, which is otherwise extremely difficult due to the presence of many spatial modes of the array. The topological synthetic space concepts proposed here offer an avenue to overcome this major technological challenge and open new opportunities in laser physics.
author_names: Zhaoju Yang

Eran Lustig

Gal Harari

Yonatan Plotnik

Yaakov Lumer

Miguel A Bandres

Mordechai Segev
title: Mode Locked Topological Insulator Laser Utilizing Synthetic Dimensions
year: 2020

abstract: Topological protection for lasers Ideas based on topology, initially developed in mathematics to describe the properties of geometric space under deformations, are now finding application in materials, electronics, and optics. The main driver is topological protection, a property that provides stability to a system even in the presence of defects. Harari et al. outline a theoretical proposal that carries such ideas over to geometrically designed laser cavities. The lasing mode is confined to the topological edge state of the cavity structure. Bandres et al. implemented those ideas to fabricate a topological insulator laser with an array of ring resonators. The results demonstrate a powerful platform for developing new laser systems. Science, this issue p. eaar4003, p. eaar4005 Lasing is observed in an edge mode of a designed optical topological insulator. INTRODUCTION Physical systems that exhibit topological invariants are naturally endowed with robustness against perturbations, as was recently demonstrated in many settings in condensed matter, photonics, cold atoms, acoustics, and more. The most prominent manifestations of topological systems are topological insulators, which exhibit scatter free edge state transport, immune to perturbations and disorder. Recent years have witnessed intense efforts toward exploiting these physical phenomena in the optical domain, with new ideas ranging from topology driven unidirectional devices to topological protection of path entanglement. But perhaps more technologically relevant than all topological photonic settings studied thus far is, as proposed by the accompanying theoretical paper by Harari et al. an all dielectric magnet free topological insulator laser, with desirable properties stemming from the topological transport of light in the laser cavity. RATIONALE We demonstrate nonmagnetic topological insulator lasers. The topological properties of the laser system give rise to single mode lasing, robustness against fabrication defects, and notably higher slope efficiencies compared to those of the topologically trivial counterparts. We further exploit the properties of the active topological platform by assembling topological insulator lasers from S chiral microresonators that enforce predetermined unidirectional lasing even in the absence of magnetic fields. RESULTS Our topological insulator laser system is an aperiodic array of 10 unit cell by 10 unit cell coupled ring resonators on an InGaAsP quantum wells platform. The active lattice uses the topological architecture suggested in the accompanying theoretical paper. This two dimensional setting is composed of a square lattice of ring resonators coupled to each other by means of link rings. The intermediary links are judiciously spatially shifted to introduce a set of hopping phases, establishing a synthetic magnetic field and two topological band gaps. The gain in this laser system is provided by optical pumping. To promote lasing of the topologically protected edge modes, we pump the outer perimeter of the array while leaving the interior lossy. We find that this topological insulator laser operates in single mode even considerably above threshold, whereas the corresponding topologically trivial realizations lase in multiple modes. Moreover, the topological laser displays a slope efficiency that is considerably higher than that in the corresponding trivial realizations. We further demonstrate the topological features of this laser by observing that in the topological array, all sites emit coherently at the same wavelength, whereas in the trivial array, lasing occurs in localized regions, each at a different frequency. Also, by pumping only part of the topological array, we demonstrate that the topological edge mode always travels along the perimeter and emits light through the output coupler. By contrast, when we pump the trivial array far from the output coupler, no light is extracted from the coupler because the lasing occurs at stationary modes. We also observe that, even in the presence of defects, the topological protection always leads to more efficient lasing compared to that of the trivial counterpart. Finally, to show the potential of this active system, we assemble a topological system based on S chiral resonators, which can provide new avenues to control the topological features. CONCLUSION We have experimentally demonstrated an all dielectric topological insulator laser and found that the topological features enhance the lasing performance of a two dimensional array of microresonators, making them lase in unison in an extended topologically protected scatter free edge mode. The observed single longitudinal mode operation leads to a considerably higher slope efficiency as compared to that of a corresponding topologically trivial system. Our results pave the way toward a new class of active topological photonic devices, such as laser arrays, that can operate in a coherent fashion with high efficiencies. Topological insulator laser. (A) Top view image of the lasing pattern (topological edge mode) in a 10 unit cell by 10 unit cell array of topologically coupled resonators and the output ports. (B) Output intensity versus pump intensity for a topological insulator laser and its trivial counterpart. The enhancement of the slope efficiency is about threefold. Comparing the power emitted in the single mode of the topological array to that of the highest power mode in the trivial array, the topological outperforms the trivial by more than a factor of 10. (C) Emission spectra from a topological insulator laser and its topologically trivial counterpart. au, arbitrary units. Physical systems exhibiting topological invariants are naturally endowed with robustness against perturbations, as manifested in topological insulators materials exhibiting robust electron transport, immune from scattering by defects and disorder. Recent years have witnessed intense efforts toward exploiting these phenomena in photonics. Here we demonstrate a nonmagnetic topological insulator laser system exhibiting topologically protected transport in the cavity. Its topological properties give rise to single mode lasing, robustness against defects, and considerably higher slope efficiencies compared to the topologically trivial counterparts. We further exploit the properties of active topological platforms by assembling the system from S chiral microresonators, enforcing predetermined unidirectional lasing without magnetic fields. This work paves the way toward active topological devices with exciting properties and functionalities.
author_names: Miguel A Bandres

Steffen Wittek

Gal Harari

Midya Parto

Jinhan Ren

Mordechai Segev

Demetrios N Christodoulides

Mercedeh Khajavikhan
title: Topological insulator laser: Experiments
venue: Science
year: 2018

abstract: Topological protection for lasers Ideas based on topology, initially developed in mathematics to describe the properties of geometric space under deformations, are now finding application in materials, electronics, and optics. The main driver is topological protection, a property that provides stability to a system even in the presence of defects. Harari et al. outline a theoretical proposal that carries such ideas over to geometrically designed laser cavities. The lasing mode is confined to the topological edge state of the cavity structure. Bandres et al. implemented those ideas to fabricate a topological insulator laser with an array of ring resonators. The results demonstrate a powerful platform for developing new laser systems. Science, this issue p. eaar4003, p. eaar4005 Lasing is observed in an edge mode of a designed optical topological insulator. INTRODUCTION Topological insulators emerged in condensed matter physics and constitute a new phase of matter, with insulating bulk and robust edge conductance that is immune to imperfections and disorder. To date, topological protection is known to be a ubiquitous phenomenon, occurring in many physical settings, ranging from photonics and cold atoms to acoustic, mechanical, and elastic systems. So far, however, most of these studies were carried out in entirely passive, linear, and conservative settings. RATIONALE We propose topological insulator lasers: lasers whose lasing mode exhibits topologically protected transport without magnetic fields. Extending topological physics to lasers is far from natural. In fact, lasers are built on foundations that are seemingly inconsistent with the essence of topological insulators: They require gain (and thus are non Hermitian) they are nonlinear entities because the gain must be saturable, and they are open systems because they emit light. These properties, common to all lasers, cast major doubts on the possibility of harnessing topological features to make a topological insulator laser. Despite this common mindset, we show that the use of topological properties leads to highly efficient lasers, robust to defects and disorder, with single mode lasing even at conditions high above the laser threshold. RESULTS We demonstrate that topological insulator lasers are theoretically possible and experimentally feasible. We consider two configurations involving planar arrays of coupled active resonators. The first is based on the Haldane model, archetypical for topological systems. The second model, geared toward experiment, constitutes an aperiodic array architecture creating an artificial magnetic field. We show that by introducing saturable gain and loss, it is possible to make these systems lase in a topological edge state. In this way, the lasing mode exhibits topologically protected transport; the light propagates unidirectionally along the edges of the cavity, immune to scattering and disorder, unaffected by the shape of the edges. Moreover, we show that the underlying topological properties not only make the system robust to fabrication and operational disorder and defects, they also lead to a highly efficient single mode lasing that remains single mode even at gain values high above the laser threshold. The figure describes the geometry and features of a topological insulator laser based on the Haldane model while adding saturable gain, loss, and an output port. The cavity is a planar honeycomb lattice of coupled microring resonators, pumped at the perimeter with a lossy interior. We show that under these conditions, lasing occurs at the topological edge mode, which has unidirectional flux and is extended around the perimeter with almost uniform intensity. The topological cavities exhibit higher efficiency than the trivial cavity, even under strong disorder. For the topological laser with a small gap, the topological protection holds as long as the disorder level is smaller than the gap size. DISCUSSION The concept of the topological insulator laser alters current understanding of the interplay between disorder and lasing, and opens exciting possibilities at the interface of topological physics and laser science, such as topologically protected transport in systems with gain. We show here that the laser system based on the archetypal Haldane model exhibits topologically protected transport, with features similar to those of its passive counterpart. This behavior means that this system is likely to have topological invariants, despite the nonhermiticity. Technologically, the topological insulator laser offers an avenue to make many semiconductor lasers operate as one single mode high power laser. The topological insulator laser constructed from an aperiodic array of resonators was realized experimentally in an all dielectric platform, as described in the accompanying experimental paper by Bandres et al. Topological insulator laser based on the Haldane model and its efficiency. (A) Planar honeycomb lattice of coupled microring resonators pumped at the perimeter. The topological lasing mode has unidirectional flux with almost uniform intensity, which builds up as the mode circulates and drops when passing the output coupler. (B) Slope efficiency (in arbitrary units) versus disorder strength for three cases differing only in the Haldane phase (of the next to nearest neighbor coupling) a topological laser with the maximum gap (blue; Haldane phase of p/2) one with a small topological gap (red; Haldane phase of p/8) and a topologically trivial laser with no gap (black; Haldane phase of 0) Topological insulators are phases of matter characterized by topological edge states that propagate in a unidirectional manner that is robust to imperfections and disorder. These attributes make topological insulator systems ideal candidates for enabling applications in quantum computation and spintronics. We propose a concept that exploits topological effects in a unique way: the topological insulator laser. These are lasers whose lasing mode exhibits topologically protected transport without magnetic fields. The underlying topological properties lead to a highly efficient laser, robust to defects and disorder, with single mode lasing even at very high gain values. The topological insulator laser alters current understanding of the interplay between disorder and lasing, and at the same time opens exciting possibilities in topological physics, such as topologically protected transport in systems with gain. On the technological side, the topological insulator laser provides a route to arrays of semiconductor lasers that operate as one single mode high power laser coupled efficiently into an output port.
author_names: Gal Harari

Miguel A Bandres

Yaakov Lumer

Mikael C Rechtsman

Yidong Chong

Mercedeh Khajavikhan

Demetrios N Christodoulides

Mordechai Segev
title: Topological insulator laser: Theory
venue: Science
year: 2018

abstract: We demonstrate a nonmagnetic topological insulator laser exhibiting topologically protected transport. The topological properties of the system give rise to single mode lasing, robustness against fabrication defects, and higher slope efficiencies compared to its trivial counterpart.
author_names: Miguel A Bandres

Steffen Wittek

Gal Harari

Midya Parto

Jinhan Ren

Mordechai Segev

Demetrios N Christodoulides

Mercedeh Khajavikhan
title: Topological Insulator Laser
year: 2018

abstract: We introduce a class of topological lasers based on the photonic Floquet topological insulator concept. The proposed system is realized as a truncated array of the lasing helical waveguides, where the pseudo magnetic field arises due to twisting of the waveguides along the propagation direction that breaks the time reversal symmetry and opens up a topological gap. When sufficient gain is provided in the edge channels of the array then the system lases into the topological edge states. Topological lasing is stable only in certain intervals of the Bloch momenta, that ensure a dynamic, but stable balance between the linear amplification and nonlinear absorption leading to the formation of the breathing edge states. We also illustrate topological robustness of the edge currents by simulating lattice defects and triangular arrangements of the waveguides.
author_names: Sergey K Ivanov

Yiqi Zhang

Yaroslav V Kartashov

Dmitry V Skryabin
title: Floquet topological insulator laser
year: 2019

abstract: We describe the recent progress on topological insulator lasers, where we employed the fundamental concepts of topological insulators in the non Hermitian laser system, to force an array of many semiconductor (InGaAs) resonators to lock together and act as one coherent laser source.
author_names: Gal Harari

Miguel A Bandres

Steffen Wittek

Midya Parto

Demetrios N Christodoulides

Mercedeh Khajavikhan

Mordechai Segev
title: Topological Insulator Laser
venue: 2019 24th Microoptics Conference (MOC)
year: 2019

abstract: We demonstrate a nonmagnetic topological insulator laser exhibiting topologically protected transport. The topological properties of the system give rise to single mode lasing, robustness against fabrication defects, and higher slope efficiencies compared to its trivial counterpart.
author_names: Miguel A Bandres

Steffen Wittek

Gal Harari

Midya Parto

Jinhan Ren

Mordechai Segev

Demetrios N Christodoulides

Mercedeh Khajavikhan
title: Experimental Realization of Magnetic Free Topological Insulator Laser
venue: 2018 Conference on Lasers and Electro Optics (CLEO)
year: 2018

abstract: We propose a practical design to implement of a topological insulator laser. Due to the topological protection, the topological laser maintains a high slope efficiency and single mode lasing even in the presence of defects and disorder.
author_names: Steffen Wittek

Gal Harari

Miguel A Bandres

H Hodaei

Midya Parto

Parinaz Aleahmad

Mikael C Rechtsman

Yidong Chong

Demetrios N Christodoulides

Mercedeh Khajavikhan

Mordechai Segev
title: Towards the experimental realization of the topological insulator laser
venue: 2017 Conference on Lasers and Electro Optics (CLEO)
year: 2017

abstract: We present the fundamentals of the recently invented topological insulator lasers.
author_names: Mordechai Segev

Miguel A Bandres

Gal Harari

Steffen Wittek

Demetrios N Christodoulides

Mercedeh Khajavikhan
title: Experimental Realization of Magnetic Free Topological Insulator Laser
venue: 2018 IEEE Photonics Society Summer Topical Meeting Series (SUM)
year: 2018