The dielectric properties of an elastomeric polymer are modified with the inclusion of dopants, with the aim of reducing dielectric loss in the terahertz range. Polydimethylsiloxane (PDMS) is selected as the host polymer, and micro/nano-particle powders of either alumina or polytetrafluoroethylene (PTFE) are employed as dopants. Composite samples are prepared, and characterised with terahertz time-domain spectroscopy (THz-TDS). The samples exhibit significantly reduced dielectric loss, with a maximum reduction of 15.3% in loss tangent reported for a sample that is 40% PTFE by mass. Results are found to have reasonable agreement with the Lichtenecker logarithmic mixture formula, and any deviation can be accounted for by agglomeration of dopant micro/nano-particles. The new dielectric composites are promising for devising efficient micro-structure components at terahertz frequencies.

Lanthanoid-doped Gallium Nitride (GaN) semiconductors are a promising class of materials with the potential to be used across a range of novel quantum optelectronic all-locations including room temperature single photon sources. However, to date there is relatively little understood about the properties of small lanthanoid ensembles, which is required before this class of materials can reach their full potential. This paper reports room temperature optical properties of submicron extent implanted-Praseodymium (Pr) in GaN. Thermal annealing at 1200 °C is conducted for the Pr implanted GaN using SiN cap technique to activate implanted-Pr as luminescent centers. The photoluminescence shows two main peaks at 650.3 and 652.0 nm originating from the 3 P 0 → 3 F 2 transition in 4f-shell of Pr 3+ . We explore the saturation behavior of the photoluminescence intensity. The implanted-Pr activation ratio in a 100 nm × 100 nm region is estimated to be 1.7% in the case of 532 nm excitation.

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A method of reducing the dielectric loss of polydimethylsiloxane (PDMS) in the terahertz range with dopants is presented. Samples of PDMS are doped with varied concentrations of polytetrafluoroethylene (PTFE) micro-particles, and characterized with terahertz time domain spectroscopy (THz-TDS) in order to extract their material properties. It is found that controlled doping can significantly reduce dielectric loss in PDMS at terahertz frequencies, and for the sample with highest dopant concentration, a 15.3% average reduction in loss tangent is demonstrated over a range from 0.3 to 1 THz. Measured material properties are compared with the Lichtenecker logarithmic mixture formula, and approximate agreement is attained.