Design of fiber coupled Er3+:chalcogenide microsphere amplifier via particle swarm optimization algorithm

Abstract

Abstract. A mid-IR amplifier consisting of a tapered chalcogenide fiber coupled to an Er 3þ -doped chalcogenide microsphere has been optimized via a particle swarm optimization (PSO) approach. More precisely, a dedicated three-dimensional numerical model, based on the coupled mode theory and solving the rate equations, has been integrated with the PSO procedure. The rate equations have included the main transitions among the erbium energy levels, the amplified spontaneous emission, and the most important secondary transitions pertaining to the ion-ion interactions. The PSO has allowed the optimal choice of the microsphere and fiber radius, taper angle, and fiber-microsphere gap in order to maximize the amplifier gain. The taper angle and the fiber-microsphere gap have been optimized to efficiently inject into the microsphere both the pump and the signal beams and to improve their spatial overlapping with the rare-earth-doped region. The employment of the PSO approach shows different attractive features, especially when many parameters have to be optimized. The numerical results demonstrate the effectiveness of the proposed approach for the design of amplifying systems. The PSO-based optimization approach has allowed the design of a microsphere-based amplifying system more efficient than a similar device designed by using a deterministic optimization method. In fact, the amplifier designed via the PSO exhibits a simulated gain G ¼ 33.7 dB, which is higher than the gain G ¼ 6.9 dB of the amplifier designed via the deterministic method.

Modeling of Whispering Gallery Modes for Rare Earth Spectroscopic Characterization

“…A calibration of the measurement system could be necessary since taper waist and taper-microsphere gap cannot be known to the nanometer scale. Alternatively, the taper waist and taper-microsphere gap can be considered as unknown parameters to be recovered in addition to the rare earth ones but longer calculation time is required [3]. In actual cases the errors E [%] and the standard deviations  PSO of PSO recovered values depend on the uncertainty of the parameters employed in the model.…”

“…The ad-hoc developed model allows the calculation of i) the resonance frequencies, the electromagnetic field profiles and propagation constants of WGMs; ii) the coupling of the optical power from the tapered fiber to the microsphere WGMs; iii) the interaction of WGMs with microsphere erbium ions via the rate equations of the ion level populations; iv) the time evolution of WGM powers [3][4][5]. The transitions among the erbium energy levels, the amplified spontaneous emission and secondary transitions pertaining to the ion-ion interactions are included in the model [4].…”

“…In [3] a mid-IR optical amplifier, consisting of a tapered chalcogenide Ga 5 Ge 20 Sb 10 S 65 fiber coupled to an Er 3+ doped microsphere made of the same glass, was optimized by means of a particle swarm optimization (PSO) approach.…”

Fractional‐Calculus‐Based Electromagnetic Tool to Study Pulse Propagation in Arbitrary Dispersive Dielectrics

“…On the other hand, the nature of the fractional order operators modelling the dielectric response enables its incorporation into time‐domain Maxwell's equations. Finally, applying a dedicated optimization algorithm based on the enhanced weighted quantum particle swarm optimization and a suitable relative error function the free parameters can be evaluated. This method is versatile because its capability to deal with every data, it can reproduce fine details, and it proved to feature superior effectiveness in terms of convergence rate and accuracy in comparison with alternative evolutionary stochastic search methods available in the scientific literature .…”

Optimization of Mid-IR microstructured fiber laser based on dysprosium doped chalcogenide glass

“…The PSO is inspired by the behaviour of a swarm (populations) of M individuals of bees (trial solutions or particles), which fly in a field (N-dimensional search space) to search for food, i.e., high density of flowers (to maximize/minimize a fitness function). More details are reported in [9]. The parameters describing the device are the following: fiber laser dopant concentration N 1 and length L 1 , reflectivities R 1 and R 2 of the mirrors, fiber amplifier doping concentration N 2 and length L 2 .…”