Dynamic Airy imaging through high-efficiency broadband phase microelements by femtosecond laser direct writing
Ze Cai, Xinbo Qi, Deng Pan, Shengyun Ji, Jincheng Ni, Zhaoxin Lao, Xin Chen, Jiawen Li, Yanlei Hu, Dong Wu, Jiaru Chu
Abstract
Manipulating Airy beams to symmetric Airy beams (SABs) with abruptly autofocusing and self-accelerating properties has attracted much attention. With such a particular propagation dynamic, SABs may provide great potential in dynamic signal imaging. On the other hand, the generation of SABs by spatial light modulators suffers from the limitations of phase gradient accuracy, low optical efficiency ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m1"> <mml:mrow> <mml:mo form="prefix"><</mml:mo> <mml:mn>40</mml:mn> <mml:mi>%</mml:mi> </mml:mrow> </mml:math> ), and a bulky footprint. Therefore, exploring imaging applications and optimal generation methods of these Airy-type beams deserves further research. Here, based on the coordinate transformation of SAB, an asymmetric Airy beam (AAB) is realized. Symmetric/asymmetric cubic phase microplates (SCPPs/ACPPs) are designed and fabricated for generating SAB/AAB. The SCPP/ACPP demonstrates superior performance: compact construction ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m2"> <mml:mrow> <mml:mn>60</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μm</mml:mi> <mml:mo>×</mml:mo> <mml:mn>60</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μm</mml:mi> <mml:mo>×</mml:mo> <mml:mn>1.1</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μm</mml:mi> </mml:mrow> </mml:math> ), continuous variation of phase, high efficiency ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m3"> <mml:mrow> <mml:mo form="prefix">∼</mml:mo> <mml:mn>81</mml:mn> <mml:mi>%</mml:mi> </mml:mrow> </mml:math> at 532 nm), and broadband operation from 405 to 780 nm. Dynamic imaging under monochromatic and polychromatic lights is realized by the SAB/AAB, indicating various results at different propagation distances with a certain initial signal. Further investigation reveals that the SCPP on a soft substrate maintains its physical dimensions and optical properties unchanged during stretching. Our work enables wide potential applications in integrated optics, beam manipulation, and imaging.