Holographic technique for measurement of the kinetic constant and optical modulation of photosensitive materials

Abstract

We use a holographic technique to measure simultaneously and separately the temporal evolution of the refractive-index and the absorption coefficient modulations induced by light in a photosensitive material. The technique is phase sensitive, allowing separation of the signals from the phase and from the amplitude grating. The refractive-index and the absorption coefficient modulations as well as the kinetic constant of the photoreaction in the positive photoresist SC 1827 were measured at three different wavelengths. The results were compared with independent measurements, performed under homogeneous exposition. The good accord demonstrates the applicability of the technique to study photosensitive materials.

Large Area Nanohole Arrays for Sensing Fabricated by Interference Lithography

“…The interference pattern is provided by an interferometric setup using a 300 mW Melles Griot solid-state laser operating at λ = 458 nm. The interferometer in this work is constituted by the superimposition of two beams and the schematics and details about the optical setup is available in [37]. Our setup allows the recording of fringe periods from 450 nm to 1800 nm and it is provided with a fringe locker system, which warrants the high contrast of the fringe pattern and the repeatability of the exposures [37].…”

“…The interferometer in this work is constituted by the superimposition of two beams and the schematics and details about the optical setup is available in [37]. Our setup allows the recording of fringe periods from 450 nm to 1800 nm and it is provided with a fringe locker system, which warrants the high contrast of the fringe pattern and the repeatability of the exposures [37]. Samples with periods of Λ = 575 nm and Λ = 675 nm were fabricated for this work.…”

Enhanced extraordinary terahertz transmission through coupling between silicon resonators

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Estudo de materiais fotossensíveis utilizando exposições holográficas

“…Assim, utilizando um segundo fotodetector, posicionado numa das duas direções dos feixes transmitidos pela amostra (Fig. [3][4][5][6][7][8][9][10][11][12][13][14][15], conectado a dois amplificadores lock in, teremos que as amplitudes dos sinais de primeiro harmônico e segundo harmônicos serão proporcionais à eficiência de difração da rede de fase e de amplitude que estão se formando respectivamente [76]:…”