Chaos-Assisted Directional Light Emission from Microcavity Lasers

Shinohara, Susumu; Harayama, Takahisa; Fukushima, Tetsuya; Hentschel, Martina; Sasaki, Tetsuo; Narimanov, Evgenii E.

doi:10.1103/physrevlett.104.163902

Cited by 135 publications

(121 citation statements)

References 21 publications

(17 reference statements)

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“…16. Shinohara et al (2010Shinohara et al ( , 2011b were the first to provided clear experimental evidence for dynamical tunneling in optical microcavities. They used a cavity whose ray dynamical phase space consists of a dominant chaotic region and an island chain, supporting a rectangular-shaped ray orbit fully confined by total internal reflection.…”

Section: Dynamical Tunnelingmentioning

confidence: 99%

Dielectric microcavities: Model systems for wave chaos and non-Hermitian physics

2015

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Section: Dynamical Tunnelingmentioning

confidence: 99%

Dielectric microcavities: Model systems for wave chaos and non-Hermitian physics

2015

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“…Moreover, modifying the shape of the pump introduces changes to both the spatial and spectral properties of lasing modes [33,[36][37][38]. Such difficulties are typically absent in more conventional lasers, which have employed pump shaping, both electrically [39][40][41][42] and optically [43], to select favorable lasing modes. The question is, can shaping of the incident pump field achieve taming of random lasers?…”

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Taming Random Lasers through Active Spatial Control of the Pump

et al. 2012

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Active control of the pump spatial profile is proposed to exercise control over random laser emission. We demonstrate numerically the selection of any desired lasing mode from the emission spectrum. An iterative optimization method is employed, first in the regime of strong scattering where modes are spatially localized and can be easily selected using local pumping. Remarkably, this method works efficiently even in the weakly scattering regime, where strong spatial overlap of the modes precludes spatial selectivity. A complex optimized pump profile is found, which selects the desired lasing mode at the expense of others, thus demonstrating the potential of pump shaping for robust and controllable singlemode operation of a random laser.PACS numbers: 42.55. Zz,42.25.Dd Multiple scattering of light in random media can be actively manipulated through spatial shaping of the incident wavefront [1]. This technique has allowed advances in focusing [2][3][4], and imaging [5,6], paving the road to actual control of light transport in strongly scattering media [7][8][9]. Introducing gain in disordered media allows amplification of multiply scattered light, leading to the observation of random lasing [10]. The broad range of systems where it has been studied [11] and the fundamental questions it has raised [12,13] has captivated the community for this last decade. Prospective of random lasing is however strongly hindered by the absence of emission control: random lasers are highly multimode with unpredictable lasing frequencies and polydirectional output. Manipulation of the underlying random structure [14][15][16][17][18][19][20][21][22][23] and recent work constraining the range of lasing frequencies [24,25] have resulted in significant progress toward possible control. However, the ability to choose a specific frequency in generic random lasing systems has not yet been achieved. The spatial profile of the pump is an interesting degree of freedom readily available in random laser (e.g., [26,27]). In a regime of very strong scattering where the modes of the random system are spatially localized [28], local pumping allows selection of spatially non-overlapping modes [29,30]. In weaker scattering media however (e.g., [31][32][33]), several hurdles appear toward achieving fine control. Selecting modes is complicated by a narrow distribution of lasing thresholds [34,35] and spatial mode overlap. Increased pumping required in these lossy systems begins to alter the random laser itself. Moreover, modifying the shape of the pump introduces changes to both the spatial and spectral properties of lasing modes [33,[36][37][38]. Such difficulties are typically absent in more conventional lasers, which have employed pump shaping, both electrically [39][40][41][42] and optically [43], to select favorable lasing modes. The question is, can shaping of the incident pump field achieve taming of random lasers?In this letter, we exercise control over the distribution of lasing thresholds via the pump geometry to choose the random laser em...

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“…Spatially nonuniform pumping schemes have previously been used to control various lasing characteristics, including emission directionality, thresholds, and frequencies in microdisks [8], spirals [9,21], asymmetric resonant cavities (ARC) [22,23], and random lasers [24][25][26][27][28][29], mostly in the single-mode regime and generally in a rather ad-hoc manner. To our knowledge, the present work is the first one to propose it as a scheme to systematically boost laser power in the multi-mode regime.…”

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confidence: 99%

Enhancement of laser power-efficiency by control of spatial hole burning interactions

Malik

Türeci

2014

Nature Photon

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The laser is an out-of-equilibrium nonlinear wave system where the interplay of the cavity geometry and nonlinear wave interactions, mediated by the gain medium, determines the self-organized oscillation frequencies and the associated spatial field patterns. In the steady state, a constant energy flux flows through the laser from the pump to the far field, with the ratio of the total output power to the input power determining the power-efficiency. While nonlinear wave interactions have been modelled and well understood since the early days of laser theory, their impact on the power-efficiency of a laser system is poorly understood. Here, we show that spatial hole burning interactions generally decrease the power efficiency. We then demonstrate how spatial hole burning interactions can be controlled by a spatially tailored pump profile, thereby boosting the power-efficiency, in some cases by orders of magnitude.Power-efficiency of lasers is a key property to be maximized to reduce energy requirements for on-chip applications, facilitate thermal management and pack lasers into smaller volumes. Earlier work on solid-state lasers addressed the quantum design of the gain medium and the optimization of carrier transport, demonstrating strong improvements in power-efficiency [1,2]. Far less systematic work has addressed the fundamental factors limiting the power efficiency of lasers and effective methods to overcome these, taking into account specific resonator properties. In particular, the impact of spatial hole burning interactions is poorly understood [3]. A case in point are the findings of Ref. [4], where the output power of microcavity quantum cascade lasers was found to increase exponentially with boundary deformation, resulting in a power enhancement over two orders of magnitude with respect to identical lasers of circular cross-section. After more than a decade of theoretical development, the fundamental factors behind this dramatic increase in power efficiency remain unknown. The goal of this paper is to provide a theoretical analysis of the mechanisms at work that enable such dramatic improvements in laser power efficiency.Typically, the pump power in a microlaser is deposited uniformly across the entire cavity area [ Fig. 1(a)] and lasing naturally occurs in cavity modes with the longest cavity lifetimes. Here we show the existence of a maximally power-efficient "optimally out-coupled mode" that may never turn on in a uniformly pumped cavity due to spatial-hole burning interactions. We further show that a non-uniform pump distribution designed to selectively pump the optimally out-coupled mode can lead to strong power enhancements.Spatially non-uniform pump distributions can be realized by fabricating patterned contacts [5], by spatially non-uniform doping in the case of current injection lasers [6,7], or by using spatial light modulators or special lenses for optically pumped lasers [8,9] (see Fig. 1(b)). We discuss the optimal spatial profile of the pump for a given resonator to maximize the power effic...

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Chaos-Assisted Directional Light Emission from Microcavity Lasers

Cited by 135 publications

References 21 publications

Dielectric microcavities: Model systems for wave chaos and non-Hermitian physics

Dielectric microcavities: Model systems for wave chaos and non-Hermitian physics

Taming Random Lasers through Active Spatial Control of the Pump

Enhancement of laser power-efficiency by control of spatial hole burning interactions

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