Xia Chun, Gutierrez Jesus J, Kuebler Stephen M, Rumpf Raymond C, Touma Jimmy
Opt Express. 2022 Mar 14;30(6):9165-9180. doi: 10.1364/OE.452467.
Photonic crystals can be engineered so that the flow of optical power and the phase of the field are independently controlled. The concept is demonstrated by creating a self-collimating lattice with an embedded cylindrical lens. The device is fabricated in a photopolymer by multi-photon lithography with the lattice spacing chosen for operation around the telecom wavelength of 1550 nm. The lattice is based on a low-symmetry rod-in-wall unit cell that strongly self-collimates light. The walls are varied in thickness to modulate the effective refractive index so light acquires a spatially quadratic phase profile as it propagates through the device. Although the phase of the field is altered, the light does not focus within the device because self-collimation forces power to flow parallel to the principal axes of the lattice. Upon exiting the device, ordinary propagation resumes in free space and the curved phase profile causes the light to focus. An analysis of the experimentally observed optical behavior shows that the device behaves like a thin lens, even though the device is considerably thick.
光子晶体可以通过设计来独立控制光功率流和场的相位。通过创建一个嵌入圆柱透镜的自准直晶格来证明这一概念。该器件采用多光子光刻技术在光聚合物中制造，晶格间距选择为在1550nm的电信波长附近工作。该晶格基于一个低对称性的壁中棒单元胞，它能强烈地使光自准直。壁的厚度是变化的，以调制有效折射率，这样光在通过器件传播时会获得一个空间二次相位分布。虽然场的相位发生了改变，但光在器件内不会聚焦，因为自准直力使功率平行于晶格的主轴流动。离开器件后，在自由空间中恢复正常传播，弯曲的相位分布使光聚焦。对实验观察到的光学行为的分析表明，该器件的行为类似于一个薄透镜，尽管该器件相当厚。
