Two-photon-induced polarization-multiplexed and multilevel storage in photoisomeric copolymer film

Abstract

We present a two-photon-induced polarization-multiplexed and multilevel data storage method with a bisazobenzene copolymer film. A polarization-adjustable femtosecond pulsed laser is used as writing beam to induce anisotropy, and the recorded information is retrieved by a CCD sensor from the film with corresponding polarized illumination. It is found that the optical axis of bisazobenzene molecules can be reoriented under two-photon excitation by the polarized femtosecond laser via a photoisomerization process. Polarization-multiplexed and multilevel storage is demonstrated by using this method. The capability to combine both advantages of these distinct techniques makes it a novel approach to obtain higher optical data density.

Study on the rewritability of bisazobenzene-containing films in optical storage based on two-photon process

“…The first readout mode is a reflection confocal microscope, that is to say, the recorded data are read by detecting the difference of the reflected readout light signal between the written area and unwritten area using a photomultiplier tube (PMT) [19]. The second mode is a transmission microscope [20]. In other words, the recorded data are read by detecting the difference of the transmitted readout light using a charge coupled device (CCD) with a polarized white light placed below the PZT scanner as the readout light.…”

“…Based on reversible birefringence associated with photo isomerization under the TPA excitation, M. Gu et al succeeded to obtain the rewritable polarization-encoded multilayer data storage in a polystyrene (PS) film doped with the azo dye 2,5-dimethyl-4-(pnitrophenylazo) anisole (DMNPAA) [18]. In our previous work, twophoton-induced polarization storage in the bisazobenzene copolymer (poly(MMA-co-M2BAN)) film has been realized based on the good TPA property and high birefringence of bisazobenzene [19,20].…”

High-efficiency fabrication of aspheric microlens arrays by holographic femtosecond laser-induced photopolymerization

“…[6][7][8] Fabrication of microlens array by means of femtosecond laser induced TPP was firstly reported by us several years ago. 9 While facing the same problem as SPDT technology, the employment of femtosecond laser single-point writing to produce aspheric microlens arrays (AMLAs) is rather time-consuming.…”

Six-dimensional optical storage utilizing wavelength selective, polarization sensitive, and reflectivity graded Bragg reflectors

“…The wavelength sensitivity and writing beam intensity dependent diffractive efficiency of two-photon gratings have been observed 20 , 17 , 13 . The polarization sensitivity of the medium with two-photon induced polarization anisotropy has also been observed 16 .…”