High sensitization efficiency and energy transfer routes for population inversion at low pump intensity in Er organic complexes for IR amplification

Optical gain at 1.55 µm of Er(TMHD)3 complex doped polymer waveguides based on the intramolecular energy transfer effect

Based on the intramolecular energy transfer mechanism between organic ligand TMHD (2, 2, 6, 6-tetramethyl-3, 5-heptanedione) and central Er³⁺ ions, optical gains at 1.55 µm were demonstrated in three structures of polymer waveguides using complex Er(TMHD)₃-doped polymethylmethacrylate (PMMA) as the active material. With the excitation of two low-power UV light-emitting diodes (LEDs) instead of 980 or 1480 nm lasers, relative gains of 3.5 and 4.1 dB cm^-1 were achieved in a 1-cm-long rectangular waveguide with an active core of Er(TMHD)₃-doped PMMA polymer. Meanwhile, relative gain of 3.0 dB cm^-1 was obtained in an evanescent-field waveguide with cross-section of 4 × 4 µm² using passive SU-8 polymer as core and a ∼1-µm-thick Er(TMHD)₃-doped PMMA as upper cladding. By growing a 100 nm thick aluminum mirror and active lower cladding, the optical gain was doubled to 6.7 dB cm^-1 in evanescent-field waveguides because of the stimulated excitation of Er³⁺ ions in the upper and lower cladding and the improved absorption efficiency.

Manipulation of Molecular Vibrations on Condensing Er3+ State Densities for 1.5 μm Application

Vibrational modes of chemical bonds in organic erbium (Er³⁺) materials play an important role in determining the efficiency of the 1.5 μm Er³⁺ emission. This work studies the energy coupling of the Er³⁺ intra-4f transitions and vibrational modes. The results demonstrate that the coupling introduces enormous nonradiative internal relaxation, which condenses the excited erbium population on to the ⁴I_13/2 state. This suggests that vibrational modes can be advantageous for optimizing the branching ratio for the 1.5 μm transition in organic erbium materials. Through control of the quenching effect on to the ⁴I_13/2 state and a reliable determination of intrinsic radiative rates, it is found that the pump power for population inversion can be reduced by an order of magnitude at high erbium concentrations compared to conventional inorganic erbium materials.

Enhanced 1.54-μm photo- and electroluminescence based on a perfluorinated Er(III) complex utilizing an iridium(III) complex as a sensitizer

Advanced 1.5-µm emitting materials that can be used to fabricate electrically driven light-emitting devices have the potential for developing cost-effective light sources for integrated silicon photonics. Sensitized erbium (Er3+) in organic materials can give bright 1.5-µm luminescence and provide a route for realizing 1.5-µm organic light emitting diodes (OLEDs). However, the Er3+ electroluminescence (EL) intensity needs to be further improved for device applications. Herein, an efficient 1.5-µm OLED made from a sensitized organic Er3+ co-doped system is realized, where a "traditional" organic phosphorescent molecule with minimal triplet-triplet annihilation is used as a chromophore sensitizer. The chromophore provides efficient sensitization to a co-doped organic Er3+ complex with a perfluorinated-ligand shell. The large volume can protect the Er3+ 1.5-µm luminescence from vibrational quenching. The average lifetime of the sensitized Er3+ 1.5-µm luminescence reaches ~0.86 ms, with a lifetime component of 2.65 ms, which is by far the longest Er3+ lifetime in a hydrogen-abundant organic environment and can even compete with that obtained in the fully fluorinated organic Er3+ system. The optimal sensitization enhances the Er3+ luminescence by a factor of 1600 even with a high concentration of the phosphorescent molecule, and bright 1.5-µm OLEDs are obtained.

Er doped layered perovskites with dual mode luminescent behavior and tunable multicolor upconversion emission

Er³⁺ doped BST nanoparticles with Aurivillius layered structure are synthesized through common solid-state method. Photoluminescence spectroscopy has shown that these oxides are capable of emitting light under UV (366 nm) and IR (980 nm) source. The effect of Er³⁺ to Yb³⁺ concentration ratio on upconversion emission are investigated and possible upconversion and energy transfer mechanisms are suggested based on the number of photons participating in UC process. Shift in the upconversion emission from green to red region is visualized by CIE chromaticity diagram. The superiority of coexistence of stoke and anti-stoke emission in a single host lattice with a single activator ion, besides to tunability of UC luminescence only by controlling sensitizer/activator ratio are very interesting features which can be used to produce dual mode multicolor luminescent ink with high security level against forgery.

Synthesis, structure and long-lived NIR luminescence of lanthanide ate complexes with perfluorinated 2-mercaptobenzothiazole

Lanthanide ate complexes with perfluorinated 2-mercaptobenzothiazole show long-lived NIR PL in hydrogen-rich media.