Efficient Optical Amplification in a Sandwich-Type Active-Passive Polymer Waveguide Containing Perylenediimides

Abstract

Polymer waveguides doped with luminescent materials serve as a suitable flexible platform for active elements (lasers and amplifiers) in on-chip optical circuits. However, at present, the best parameters (lowest thresholds) achieved with these devices are obtained with the use of the stripe excitation technique in the framework of which external illumination of an active material along the whole length of the waveguide is realized that is not convenient for the waveguide on-chip integration and requires high peak energies due to the large excitation area. In the present work, an elegant method is proposed to overcome this obstacle and provide efficient active material pumping along the whole waveguide length with use of on-chip integration compatible edge-type excitation light injection. This novel type of planar active-passive polymer waveguides includes a thin (50–100 nm) active layer of poly­(methyl methacrylate) (PMMA), which is heavily doped with highly luminescent perylenediimide (PDI) molecules, sandwiched between two cladding (passive) PMMA layers. This structure efficiently exploits the excellent light-emitting properties of PDIs with a confinement of both the excitation beam and the photoluminescence in the active PMMA–PDI film. In this way, the absence of losses in the PMMA claddings guarantees the propagation of the pump beam along the whole length of the structure (≈1 mm) in order to provide the required excitation to obtain stimulated emission. Geometrical parameters are optimized to demonstrate the amplified spontaneous emission with a threshold as low as 0.9 μJ and a line width as narrow as 2 nm.

Optical Amplification in Hollow-Core Negative-Curvature Fibers Doped with Perovskite CsPbBr3 Nanocrystals

“…It is worth noting that these three HC-NCFs in Figure 4c were doped by using the same PNC-solution with a concentration of 1 mg/mL, which is the optimum value for the fabrication process described in Section 3. A minimum amount of PNCs deposited in the HC-NCF are required, in agreement with previous results of waveguides doped with other colloidal nanocrystals or dyes [39].…”

“…Obviously, these losses are quite low and the propagation of the pump beam is assured through the entire length of the fiber, hence being effective the excitation of PL from PNCs by the evanescent field of the HC-NCF HE 11 -core mode (Figure 3e). Indeed, a similar co-propagation of pump and PL was already exploited in planar waveguide amplifiers [26,39]. From these experiments, we deduce a signal amplification or gain P out /P in (ratio of probe signal at the output facet of the fiber over that at the input one) that increases with the laser pump power and with the HC-NCF length (Figure 4c).…”

All‐Polymer Photonic Microcavities Doped with Perylene Bisimide J‐Aggregates

“…On the other hand, to the best of our knowledge, PBI J‐aggregates have never been implemented into all‐polymer matrices and structures, while only few bare PBI J‐aggregate solid state films have been reported so far. [13a,23] In this regard, Díaz‐García's group reported distributed feedback structures made of molecular PBIs embedded in a polystyrene matrix as gain medium, and Martínez‐Pastor's group demonstrated highly efficient amplified stimulated emission by molecular PBI in poly(methyl methacrylate) . Moreover, lasing effect from PBI J‐aggregates still remains a challenging goal.…”

Ultrathin Colloidal Quantum Dot Films for Optical Amplification: The Role of Modal Confinement and Heat Dissipation

“…Here, we investigate the QD films with TiO 2 layer structures as a model system comprising of a gain medium and a waveguide. The refractive index of the gain medium plays an important role in modal confinement of the lasing process, and the waveguides with a high refractive index provide a strong light confinement in the gain media enhancing their optical amplification . Along with engineering the modal confinement of the hybrid QD structures, their possible roles in heat dissipation in terms of gain and loss of optical amplification in QD solids are also discussed.…”

“…The refractivei ndex of the gain mediump lays an important role in modal confinement of the lasing process, and the waveguides with ah igh refractive index provideastrong light confinement in the gain media enhancing their optical amplification. [11] Along with engineering the modal confinement of the hybrid QD structures, their possible roles in heat dissipation in terms of gain and loss of optical amplification in QD solids are also discussed.CdSe/CdS/ZnS QDsa re synthesized according to an earlier reported procedure, [12] and Figure 1a shows the schematic of the layer-by-layer technique to produce QD films using polyethylene imine (PEI) as ac ross-linker. Previously,d rop-cast or spin-coating methods have been used to fabricate QD films, but these procedures can lead to random aggregation of QDs during their solvent evaporation and poor reproducibility.…”