Phosphine Oxide-Nd³⁺ Coordination Chains with Cumulated Output Enable Efficient LED-Pumping Optical Amplification

Area of Science:

• Materials Science
• Optoelectronics
• Inorganic Chemistry

Background:

• Near-infrared luminescent rare-earth organic complexes are crucial for optical waveguide amplification.
• Existing materials often exhibit limited optical gains (< 4 dB/cm) due to low doping concentrations.

Purpose of the Study:

• To develop novel neodymium-doped waveguide amplifiers with enhanced optical gain.
• To investigate the effect of coordination structure on luminescence and optical gain.

Main Methods:

• Synthesis of two one-dimensional (1D) Nd3+ coordination chains: [Nd(TTA)3(DBTDPO)]n (Nd1) and [Nd(TTA)3(DPEPO)]n (Nd2).
• Structural analysis focusing on Nd-Nd distances and intermolecular interactions.
• Fabrication and testing of embedded and evanescent-field waveguide amplifiers.

Main Results:

• Nd2 exhibits shorter intra- and interchain Nd-Nd distances and weaker intermolecular interactions than Nd1.
• Nd2 shows enhanced 1.06 μm emission intensity and duration due to more concentrated and radiative Nd3+ ions.
• Nd2-based waveguides achieve state-of-the-art gain maxima of 5.7 dB/cm (embedded) and 4.9 dB/cm (evanescent-field) with excellent stability.

Conclusions:

• Controllable coordination assembly of lanthanide ions enables high-density local outputs.
• The developed Nd2 material effectively suppresses luminescence quenching, leading to superior optical gain.
• This approach offers a flexible strategy for designing advanced rare-earth-doped optical waveguide amplifiers.