META 2021, META'12

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Noise in surface plasmon amplifiers
Pierre Berini, Israel De Leon

Last modified: 2011-12-05

Abstract


Surface plasmon amplifiers and lasers (oscillators) have been topics of investigation for about three decades, culminating in several recent demonstrations of amplification and lasing [1]. Noise in such systems is of foremost importance as it constrains information capacity. An expression for the noise figure of high-gain surface plasmon amplifiers incorporating dipolar gain media has been obtained in terms of the spontaneous emission rate into the amplified SPP, taking into account the different energy decay channels experienced by dipoles in close proximity to the metallic surface [2]. Two amplifier structures are examined: a single-interface between a metal and a gain medium and a thin metal film bounded by identical gain media on both sides. A realistic configuration is considered where the SPP undergoing amplification has a Gaussian profile in the plane of the metal and paraxial propagation along the amplifier’s length. The noise figure of these plasmonic amplifiers is studied considering three prototypical gain media with different permittivities. It is shown that the noise figure exhibits a strong dependence on the real part of the permittivities of the metal and gain medium, and that its minimum value is 4/√π (∼ 3.53 dB). The origin of this minimum value is discussed. It is also shown that amplifier configurations supporting strongly confined surface plasmon-polaritons suffer from a large noise figure, which follows from an enhanced spontaneous emission rate due to the Purcell effect.

Keywords


Plasmons, amplifiers, lasers