image: A focused 473 nm laser beam is irradiated into the glass, and the blue area is the photochromic region of the glass. The 3D optical data are written in transparent glass by a computer-controlled 3D XYZ translation stage. A 465 nm light from xenon lamp is used to excite the glass, and the photochromism-induced luminescence modification is recorded by a CCD camera. The transmittance or luminescence modulation is recovered by the thermal stimulation. view more
Credit: by Zhen Hu, Xiongjian Huang, Zhengwen Yang, Jianbei Qiu, Zhiguo Song, Junying Zhang, and Guoping Dong
The advent of information age is accompanied by the rapid growth of digital information, which is in urgent need for the development of huge storage space and security media. Optical storage technology with the huge storage capacity and low cost has become a new choice for the information storage. Meanwhile, the 3D information storage medium has been a good selection for improving the information storage capacity and extending storage life. At present, the transparent glass has been proved as a viable information recording 3D medium under the processing of near-infrared femtosecond laser. However, the femtosecond laser is a complicated and expensive equipment in contrast to the visible continuous semiconductor laser, and it usually requires a higher photon energy and a more complex operating process. Thus these characteristics urge us to develop a new information recording technology for the bulk glass medium.
In a new paper published in Light Science & Application, a team of scientists, led by Professor Zhengwen Yang from College of Materials Science and Engineering, Kunming University of Science and Technology, China, and co-workers have developed a rare earth ions doped transparent glass, which can be used as 3D optical information storage and data encryption medium based on their reversible transmittance and photoluminescence manipulation. The color of rare earth ions doped glass reversibly changes from light yellow to blue by alternating 473 nm laser illumination and thermal stimulation due to the change of W6+ valence state, showing the writing and erasing ability. The reading out of optical information can be achieved by the transmittance and photoluminescence modulation of the rare earth doped glasses. It is interesting that the optical information can be recorded in arbitrary 3D space of transparent glass, and the optical information written in the 3D space of transparent glass can be hierarchically discriminated, thus the encryption function can be obtained.
The photo-modulated glass is of importance for extending their new applications in the optoelectronic fields:
We demonstrate, that three-dimensional (3D) optical information can be written inside transparent glass by semiconductor blue laser (473 nm) direct writing instead of high-cost femtosecond laser.
We found, for the first time, that rare earth ions doped transparent glass can be as the 3D optical data storage medium based on their reversible transmittance or photoluminescence modulation. The information can be stored and readout in transparent glass through holographic pattern, two-dimensional code pattern and binary dot arrays, etc.
We opened new opportunities in the information security, that the optical information can be recorded in arbitrary 3D space of transparent glass, and can be hierarchically discriminate, thus the information encryption function can be obtained.
We believe that this photo-modulated glass is of importance for extending their new applications in the optoelectronic fields, such as holographic technology, quantum information processing, optical computing systems, and etc.