Femtosecond laser ablation of transparent microphotonic devices and computer-generated holograms

Abstract

Femtosecond laser ablation allows direct patterning of engineering materials in industrial settings without requiring multistage processes such as photolithography or electron beam lithography. However, femtosecond lasers have not been widely used to construct volumetric microphotonic devices and holograms with high reliability and cost efficiency. Here, a direct femtosecond laser writing process is developed to rapidly produce transmission 1D/2D gratings, Fresnel Zone Plate lenses, and computer-generated holograms. The optical properties including light transmission, angle-dependent resolution, and light polarization effects for the microphotonic devices have been characterized. Varying the depth of the microgratings from 400 nm to 1.5 μm allowed the control over their transmission intensity profile. The optical properties of the 1D/2D gratings were validated through a geometrical theory of diffraction model involving 2D phase modulation. The produced Fresnel lenses had transmission efficiency of ∼60% at normal incidence and they preserved the polarization of incident light. The computer-generated holograms had an average transmission efficiency of 35% over the visible spectrum. These microphotonic devices had wettability resistance of contact angle ranging from 44° to 125°. These devices can be used in a variety of applications including wavelength-selective filters, dynamic displays, fiber optics, and biomedical devices.

Laser inscription of pseudorandom structures for microphotonic diffuser applications

“…The presented technique provides a fast and economically viable approach for fabricating glass optical diffusers compare to femtosecond laser. 33,54 A numerical model was developed to simulate the laser ablation process on the soda-lime glass substrates. This study examines the effect of implementing different surface relief microstructures and increasing the diffusing surfaces on the optical performance.…”

Analysis of a microreactor for synthesizing nanocrystals by computational fluid dynamics

“…[12] Among the techniques available for fabrication of microreactors with serpentine channels and T-junctions, femtosecond laser ablation has been drawing attention because it allows machining of a variety of materials, including metals, glass, and ceramics. [14][15][16][17][18] Mechanical micromachining and electric discharge machining wear out the equipment used in the process, while a focused ion beam machining is performed under vacuum; such techniques also require small etching velocities, not allowing fast prototyping. [19] Lithography methods and deep reactive ion etching were adapted from the microelectro-mechanical-systems (MEMS) manufacturing, but are still expensive and complex to operate.…”

“…[19] Lithography methods and deep reactive ion etching were adapted from the microelectro-mechanical-systems (MEMS) manufacturing, but are still expensive and complex to operate. [12,16] Laser methods based on direct ablation etch materials by a heating mechanism that affects the surroundings of the focused area by heat diffusion, damaging material properties due to phase transition. [19] Femtosecond laser ablation uses high intensity beams combined with short exposure time ($10 À15 s).…”

Pulsed Laser Drilling of Engineering Plastic Films to Fabricate Through-Hole Membranes for Print-and-Imprint Method

“…In particular, the progress of short pulse lasers enables the fine processing of metals [1,2], ceramics [3,4], semiconductors [5,6], and composites [7,8] with minimal heat affected zone (HAZ) and less debris around laser-irradiated areas. Transparent materials without absorption at the wavelength of the incident laser can also be processed through multiphoton absorption due to high peak power at the focal spot [9][10][11].…”