Realizing Saturable Absorption and Reverse Saturable Absorption in a PEDOT:PSS Film via Electrical Modulation

Abstract

The electrical tuning of the nonlinear absorption of materials has promising application potential, while studies remain rare. In this work, we show that the third-order nonlinear absorption of poly(3,4-ethylenedioxythiophene) chemically doped with poly(styrene sulfonic acid) [PEDOT:PSS] can be effectively modulated by external voltage. The 2 nonlinear absorption of the film can be varied between reverse saturable absorption (RSA) and saturable absorption (SA) via voltage control with laser excitation at 800 nm, and corresponding nonlinear absorption coefficient can be tuned in the range -1590 to 518 cm GW -1 . The doping level and energy structure of PEDOT are modulated with different voltages. The undoped film affords two-photon absorption and accordingly the RSA response. A moderately doped sample has two polaron levels, and Pauli blocking associated with these two polaron levels results in SA. The bipolaron level in heavily doped PEDOT leads to excited state absorption and therefore RSA behavior.The approach reported here can be applied to other semiconductors, being a convenient, effective, and promising method for the electrical tuning of the optical nonlinearity.

Enhanced nonlinear optical performance of perovskite films passivated by porphyrin derivatives

“…The repetition rate of the ns laser is 10 Hz. Open-aperture Z-scan data were fitted by the following expression: 38,39 Close-aperture Z-scan data were fitted by the following expression: 38 where T ( Z ) is the normalized transmittance of the sample, β represents the NLO absorption coefficient, n 2 is the nonlinear refractive index, I 0 is the on-focus laser intensity, and Z 0 is the Rayleigh length ( Z 0 = π ω 0 2 / λ , ω 0 and λ are the waist radius of the lens and the laser wavelength, respectively). L eff = [1 − exp(− α 0 L )]/ α 0 is the effective length of the sample, α 0 represents the linear absorption coefficient, and L is the thickness of the sample.…”

“…The repetition rate of the ns laser is 10 Hz. Open-aperture Z-scan data were fitted by the following expression: 38,39 TðZÞ ¼ ln 1þq 0 ðZÞ ½ q 0 ðZÞ (1)…”

Smart textiles for human–machine interface fabricated via a facile on-site vapor-phase polymerization

“…With the addition of PEG, the absorption of the PEDOT film increased gradually above 1200 nm and the intensity of the broad signal at 900-1000 nm was reduced, which indicated the polaron energy level gradually changed to the bipolaron state and the oxidation level of PEDOT increased. 52,53 We observed that the Raman and UV-Vis-NIR spectra of 12-PEDOT showed information that did not match the film conductivity. According to the research by Fabretto et al, 46 the substantial increase of the square resistance and reduction in conductivity at high PEG loading should be due to the steric hindrance of the surfactant acting to insulate individual PEDOT grains.…”

Tunable third-order nonlinear optical effect via modifying Ti4(embonate)6 cage-based ionic pairs

“…The SA effect can be applied to Q-switch or passive mode locking techniques to produce short laser pulses, while the RSA effect can be widely used in optical amplitude limiting devices, and plays a protective role for eyes or sensors. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] The SA and RSA responses are influenced by high-intensity light fields and have a dependence on the intrinsic characteristics of the optical materials. Therefore, it is an important challenge to design and synthesize novel third-order nonlinear optical materials to realize SA and RSA response conversion.…”