New Trends in Amplifiers and Sources via Chalcogenide Photonic Crystal Fibers

Rare-earth-doped chalcogenide glass fiber lasers and amplifiers have great applicative potential in many fields since they are key elements in the near and medium-infrared (mid-IR) wavelength range. In this paper, a review, even if not exhaustive, on amplification and lasing obtained by employing rare-earth-doped chalcogenide photonic crystal fibers is reported. Materials, devices, and feasible applications in the mid-IR are briefly mentioned

Collisional excitation of NH(3{\Sigma}-) by Ar: A new ab initio 3D potential energy surface and scattering calculations

Collisional excitation of light hydrides is important to fully understand the complex chemical and physical processes of atmospheric and astrophysical environments. Here, we focus on the NH(X3{\Sigma}-)-Ar van der Waals system. First, we have calculated a new three-dimensional Potential Energy Surface (PES), which explicitly includes the NH bond vibration. We have carried out the ab initio calculations of the PES employing the open-shell single- and double-excitation couple cluster method with noniterative perturbational treatment of the triple excitations. To achieve a better accuracy, we have first obtained the energies using the augmented correlation-consistent aug-cc-pVXZ (X = T, Q, 5) basis sets and then we have extrapolated the final values to the complete basis set limit. We have also studied the collisional excitation of NH(X3{\Sigma}-)-Ar at the close-coupling level, employing our new PES. We calculated collisional excitation cross sections of the fine-structure levels of NH by Ar for energies up to 3000 cm-1 . After thermal average of the cross sections, we have then obtained the rate coefficients for temperatures up to 350 K. The propensity rules between the fine-structure levels are in good agreement with those of similar collisional systems, even though they are not as strong and pronounced as for lighter systems, such as NH-He. The final theoretical values are also compared with the few available experimental data

Design of an Efficient Pumping Scheme for Mid-IR Dy3+:Ga5Ge20Sb10S65PCF Fiber Laser

This letter illustrates the design of a novel medium infrared (Mid-IR) laser based on a photonic crystal fiber made of dysprosium-doped chalcogenide glass, Dy3+:Ga5Ge20Sb10S65. In order to perform a realistic investigation, the simulation is performed by taking into account the spectroscopic parameters measured on the rare earth-doped glass sample. The simulated results show that an optical beam emission close to 4400-nm wavelength can be obtained by employing two pump beams at 2850 nm (pump #1) and 4092 nm (pump #2) wavelengths. As example, for the pump powers of 50 mW (pump #1) and 1 W (pump #2), the input mirror reflectivity of 99%, the output mirror reflectivity of 30%, and the optical cavity length of 50 cm, a signal power close to 350 mW at the wavelength of 4384 nm can be generated. This result indicates that the designed source configuration is feasible for high beam quality Mid-IR light generation and it is efficient enough to find applications in optical free propagation links, optical remote sensing, and medicine

Design of a Multi-Wavelength Fiber Laser Based on Tm:Er:Yb:Ho Co-Doped Germanate Glass

In this article, for the first time, an efficient multi-wavelength fiber laser based on a Tm:Er:Yb:Ho co-doped germanate glass, optically pumped at 980 nm wavelength and simultaneously emitting at 1550 nm, 1800 nm and 2050 nm wavelengths, is designed and optimized. An exhaustive model, taking into account the energy transfer phenomena between different rare earths, is developed. The device behavior is investigated by means of several parametric sweeps with respect to the input pump power, the fiber length, the dopant concentrations and the output mirrors reflectivities. Four optimal concentrations have been found by means of a home-made computer code based on particle swarm optimization (PSO) approach, allowing a global solution search. These concentrations allow levels of output powers very close to each other, equal to 20 mW $pm$ 0.1$$ at 1550 nm, 1800 nm and 2050 nm, respectively. These results predict the possibility of tailoring the dopant concentrations in order to construct broadband optical sources with similar emission powers at multiple wavelengths and broadband amplifiers

Design of an Efficient Pumping Scheme for Mid-IR Dy3+:Ga5Ge20Sb10S65 PCF Fiber Laser

This letter illustrates the design of a novel medium infrared (Mid-IR) laser based on a photonic crystal fiber made of dysprosium-doped chalcogenide glass, Dy3+:Ga5Ge20Sb10S65. In order to perform a realistic investigation, the simulation is performed by taking into account the spectroscopic parameters measured on the rare earth-doped glass sample. The simulated results show that an optical beam emission close to 4400-nm wavelength can be obtained by employing two pump beams at 2850 nm (pump #1) and 4092 nm (pump #2) wavelengths. The pump beams can be provided by commercial quantum cascade lasers. As example, for the pump powers of 50 mW (pump #1) and 1 W (pump #2), the input mirror reflectivity of 99%, the output mirror reflectivity of 30%, and the optical cavity length of 50 cm, a signal power close to 350 mW at the wavelength of 4384 nm can be generated. This result indicates that the designed source configuration is feasible for high beam quality Mid-IR light generation and it is efficient enough to find applications in optical free propagation links, optical remote sensing, and medicine

Novel pumping schemes of Mid-IR photonic crystal fiber lasers for aerospace applications

The paper illustrates the design of two pumping schemes for Mid-IR lasers based on photonic crystal fibers (PCFs) made of dysprosium doped chalcogenide glass Dy3+:Ga5Ge20Sb10S65. The simulation is performed by taking into account the spectroscopic parameters measured on the rare earth-doped glass sample in order to perform a realistic feasibility investigation. The first pump scheme provides an optical beam emission close to 4400 nm wavelength by employing two pump beams at the wavelengths close to 2800 nm and 4100 nm, respectively. The second pump scheme allows beam emission close to 4400 nm wavelength via a 1700 nm pump, its efficiency is increased by including a suitable optical amplifier after the laser cavity. The proposed light sources based on chalcogenide glass photonic crystal fibers (PCFs) doped with Dy3+ ions are investigated via a home-made numerical model based on the coupled mode theory and solving the rare earth rate equations. A number of promising applications in different areas such as satellite remote sensing and aerospace, biology, molecular spectroscopy and environmental monitoring are feasible

Dysprosium-doped chalcogenide Master Oscillator Power Amplifier (MOPA) for Mid-IR emission

The paper describes the design of a medium infrared fiber laser based on a dysprosium-doped chalcogenide glass Dy3+: Ga5Ge20Sb10S65. To obtain a high efficiency, the fiber laser is followed by an optical amplifier. The optimized optical source exploits a master oscillator power amplifier (MOPA) configuration. The MOPA pump and signal wavelengths are 1709 and 4384 nm, respectively. Spectroscopic parameters measured on preliminary samples of chalcogenide glasses are taken into account to fulfill realistic simulations. The MOPA emission is maximized by applying a particle swarm optimization approach. For the dysprosium concentration 6, ×, 1025 ions/m3 and the input pump power of 3 W, an output power of 637 mW can be obtained for optical fiber losses close to 1 dB m-1. The optimized MOPA configuration allows a laser efficiency larger than 21%. By considering the high beam quality provided by photonic crystal fibers, it is a good candidate for medium infrared light generation whose main applications include, but are not limited to, molecular spectroscopy and environmental monitoring

Metallo-Dielectric Multilayer Structure for Lactose Malabsorption Diagnosis through H2 Breath Test

A metallo-dielectric multilayer structure is proposed as a novel approach to the analysis of lactose malabsorption. When lactose intolerance occurs, the bacterial overgrowth in the intestine causes an increased spontaneous emission of H2 in the human breath. By monitoring the changes in the optical properties of a multilayer palladium-polymeric structure, one is able to detect the patient's disease and the level of lactose malabsorption with high sensitivity and rapid response

High sensitivity photonic crystal pressure sensor

A two-dimensional photonic crystal microcavity coupled with a waveguide is proposed to realise a high sensitive force sensor, designed on a GaAs membrane. A theoretical model is developed to evaluate the change of the refractive index induced by the application of the force onto a sensing surface. A linear calibration curve is obtained relating the resonant drop position to the applied force

Comparative modeling of infrared fiber lasers

The modeling and design of fiber lasers facilitate the process of their practical realization. Of particular interest during the last few years is the development of lanthanide ion-doped fiber lasers that operate at wavelengths exceeding 2000 nm. There are two main host glass materials considered for this purpose, namely fluoride and chalcogenide glasses. Therefore, this study concerned comparative modeling of fiber lasers operating within the infrared wavelength region beyond 2000 nm. In particular, the convergence properties of selected algorithms, implemented within various software environments, were studied with a specific focus on the central processing unit (CPU) time and calculation residual. Two representative fiber laser cavities were considered: One was based on a chalcogenide-selenide glass step-index fiber doped with trivalent dysprosium ions, whereas the other was a fluoride step-index fiber doped with trivalent erbium ions. The practical calculation accuracy was also assessed by comparing directly the results obtained from the different models