Plasmonic Quantum Dot Nanocavity Laser: Hybrid Modes

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Plasmonic Quantum Dot Nanocavity Laser: Hybrid Modes Jamal N. Jabir 1,2,3 & S. M. M. Ameen 1 & Amin Habbeb Al-Khursan 2 Received: 6 February 2020 / Accepted: 31 March 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract The hybrid modes in the plasmonic quantum dot (QD) laser are modeled using the Marctili method. The model is then used to study the mode characteristics. The modes are going to cutoff point at zero propagation constant, while it goes to surface plasmon polaritons (SPPs) mode at higher photon energy. This behavior was different from that of waveguide modes shown in the dielectric waveguide. At plasmon resonance, hybrid mode is exactly one mode: surface plasmon polariton mode (perfect electric conductor). Keywords Surface plasmon polariton . Hybrid modes . Quantum dot . Nanolaser

Introduction Ultrasmall lasers have a lot of advantages such as ultralow threshold current and high modulation bandwidth. It also has the benefit of zero power consumption as a result of the high mode cavity coupling with the single mode of the spontaneous emission [1, 2]. Attaining a tiny nanolaser is stiff by the difficulty of localizing the photon wave when its wavelength is larger than the size of the confining structure [3]. While decreasing cavity length can be done under high reflectivity coating, reducing the waveguide core below the diffraction limit is not possible in the dielectric waveguide, where the confinement factor is reduced [4]. This can be done by integrating the cavity with a metallic cladding [5]. Metals have negative permittivity at the optical frequencies as a result of electron interaction with the electromagnetic field. Electrons are propagated, in metal, at plasma frequency with quanta called plasmons. When plasmons at metallic surfaces are coupled with electromagnetic waves at the metal-dielectric interface then we have a surface plasmon polaritons (SPPs). These SPPs are less restricted by the diffraction limit. They are surface wave-like with polarization normal to the metal-dielectric

* Amin Habbeb Al-Khursan [email protected] 1

College of Science, University of Basrah, Basrah, Iraq

2

Nassiriya Nanotechnology Research Laboratory (NNRL), Science College, Thi-Qar University, Nassiriya, Iraq

3

Deptartment of Physics, College of Education, University of Al-Qadisiyah, Diwaniyah, Iraq

interface, this is the plasmonic mode. Since a significant part of this mode is confined in metal, it suffers from metal loss which is higher than the loss from the dielectric mode. Then, an active material with high gain is required to cover losses [5–7]. Quantum dots (QDs) are zero-dimensional nanostructures with completely quantized energy states similar to those in atoms. Accordingly, they are called artificial atoms. These nanocrystals have interesting characteristics, such as high gain, making them of considerably applicable in different fields. For three decades, they cover applications such as high modulation bandwidth applications, low noise, high nonlinearity, quantum co