Controllable Photonic Structures on Silicon-on-Insulator Devices Fabricated Using Femtosecond Laser Lithography

Abstract

The design of micro/nanostructures on silicon-on-insulator (SOI) devices has attracted widespread attention in the science and applications of integrated optics, which, however, are usually restricted by the current manufacturing technologies. Hence, in this paper, we propose a mask-free, one-step femtosecond laser lithography method for efficient fabrication of high-quality controllable planar photonic structures on SOI devices. Subwavelength gratings with high uniformity are flexibly prepared on a SOI wafer, and they can be efficiently extended for large-area fabrication with long-range uniformity. Different from the melt flow mechanism to bulk silicon, the buried SiO2 layer of the SOI material provides substantial control over the phase change process, thereby achieving local rapid vaporization to form a high-quality structure. The optical properties of the prepared structures are measured experimentally and determined to possess powerful diffraction and light-coupling characteristics. Strikingly, active control of the SOI surface structure morphology, from the grating to the periodic silicon wire structure, can be realized through precision adjustment of the pulse injection volumes. A homogeneous silicon photonic wire is successfully generated on the SOI device, providing an alternative to the preparation of waveguides. This effective femtosecond laser lithography method for fabricating controllable photonic structures on SOI devices is expected to further promote the development of integrated optics.

Uniformity Control of Laser-Induced Periodic Surface Structures

“…As mentioned above, ultrafast laser-induced LIPSS formation is a complex process involving mutual feedback mechanisms. [50]. (E,F) A highly uniform LIPSS was fabricated on silicon based on temporally shaped femtosecond laser pulses [67].…”

“…Feng et al utilized the feedback mechanism of the thin gold film coat on silicon surfaces for the laser processing, which enhances interfacial electron-phonon coupling to form a high and uniform electron density, and suppresses the impact of defects on the silicon, thereby achieving a uniform and stable LIPSS fabrication [49]. Recently, Huang et al deeply analyzed the structural characteristics of silicon-on-insulator (SOI) and exploited the feedback mechanism of the intermediate buried oxide layer (SiO 2 layer) of the SOI on the laser-induced phase change process to regulate the generation of subwavelength gratings [50]. For a bulk Si wafer, the multi-pulse-induced incubation heat [51,52] quickly transfers inside the substrate because of the high thermal conductivity of Si, balancing the local surface temperature of the initial structure between melting and vaporization.…”

“…As shown in Figure 2D, highly uniform subwavelength gratings are flexibly prepared on SOI based on exploiting the feedback mechanisms to regulate the formation of structures. Furthermore, periodic surface structures with high uniformity achieve superior structure coloring, and a large-area cross-scale "peace dove" pattern was flexibly prepared on an SOI wafer, which exhibits a vivid and distinguishable structural color under indoor lighting [50].…”

“…(A,B) Growth of metal-oxide periodic nanostructures with long-range uniformity by exploiting positive non-local feedback to initiate and negative local feedback to regulate [46]. (C,D) Regularizing the generation of subwavelength gratings on SOI by the feedback mechanisms of sample structural properties[50]. (E,F) A highly uniform LIPSS was fabricated on silicon based on temporally shaped femtosecond laser pulses[67].…”

High-Performance Birefringence of Periodic Nanostructures in FTO Thin Film Fabricated by IR-UV Femtosecond Laser

“…Femtosecond laser-induced periodic surface structures (LIPSS) have been studied extensively for many types of materials, such as metals, semiconductors, dielectric solids, and thin films [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Owing to its versatility and flexibility, femtosecond LIPSS has become an efficient processing technique for fabricating functional devices, for structural color, absorption and luminescence enhancement, and large-area gratings [15][16][17][18][19].…”