The linear and nonlinear optical properties of pseudoisocyanine (PIC) J aggregates in 1-D distributed feedback (DFB) microcavities, photonic crystal slabs are investigated. The linear optical properties are well described by the DFB cavity-polaritons in the slabs. A polariton mode splitting of 50 meV and a photonic band gap of 30 meV are observed in PIC J aggregates dispersed in a polyvinyl-alcohol matrix. In the pump and probe experiments, we resonantly excited the cavity mode observed at the low energy side of the excitonic resonance, the virtual-exciton excitation condition. The response time is about 0.5 ps, which is approximately equal to the pump-pulse duration. We find the enhancement of the optical nonlinearity to be one-order of magnitude in the microcavity. Excitation of the dielectric-band mode is effective in enhancing the nonlinearity with an ultrafast response.

Linear and nonlinear optical properties of pseudoisocyanine J aggregates in distributed feedback microcavities

The thermally induced and Kerr-induced nonlinearities of a pseudoisocyanine (PIC) aqueous solution were studied using 532 nm radiation. The thermally induced negative nonlinear refraction of 8 ns pulses was investigated by the pulse waveform analysis technique. The nonlinear refractive index of PIC was measured using the Z-scan technique to be γ = −6 × 10−12 cm2 W−1. It was shown that saturated absorption dominates over nonlinear refraction in this spectral range. A comparison with previously reported data of nonlinear optical characteristics of PIC solution measured using femtosecond pulses has shown the influence of additional mechanisms responsible for the increase of γ in the case of nanosecond pulses.

http://iopscience.iop.org/article/10.1088/1464-4258/6/12/004/pdf

Thermally induced and Kerr-induced optical nonlinearities of a pseudoisocyanine solution at 532 nm

The optical Stark effect (OSE) has been studied in highly oriented J-aggregates of 1,1’-diethyl-2,2’-cyanine chloride (PICCl) in vertically spin-coated PVA film under far off-resonance pump by 1 ps pulses at 1055 nm. Blue shift of few tens of cm, bleaching, and broadening of the J-band were observed. The induced changes in absorption showed instantaneous character of OSE. Polarization dependence observed is qualitatively explained supposing the dual nature of the J-band. Observed Stark shift of nearly the same magnitude in dye monomer solution indicates no exciton enhancement of the aggregate OSE response induced by far off-resonance light pulses.

http://www.itpa.lt/LFD/Lfz/471/14/Ljp47114.pdf

T Kato

Papers

Phonon-mediated coherent transients in pseudoisocyanine J aggregates