Laser inscription of pseudorandom structures for microphotonic diffuser applications

Abstract

Optical diffusers provide a solution for a variety of applications requiring a Gaussian intensity distribution including imaging systems, biomedical optics, and aerospace. Advances in laser ablation processes have allowed the rapid production of efficient optical diffusers. Here, we demonstrate a novel technique to fabricate high-quality glass optical diffusers with cost-efficiency using a continuous CO2 laser. Surface relief pseudorandom microstructures were patterned on both sides of the glass substrates. A numerical simulation of the temperature distribution showed that the CO2 laser drills a 137 μm hole in the glass for every 2 ms of processing time. FFT simulation was utilized to design predictable optical diffusers. The pseudorandom microstructures were characterized by optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy to assess their chemical properties, optical scattering, transmittance, and polarization response. Increasing laser exposure and the number of diffusing surfaces enhanced the diffusion and homogenized the incident light. The recorded speckle pattern showed high contrast with sharp bright spot free diffusion in the far field view range (250 mm). A model of glass surface peeling was also developed to prevent its occurrence during the fabrication process. The demonstrated method provides an economical approach in fabricating optical glass diffusers in a controlled and predictable manner. The produced optical diffusers have application in fibre optics, LED systems, and spotlights.

Highly Flexible, Stretchable, and Tunable Optical Diffusers with Mechanically Switchable Wettability Surfaces

“…The advanced diffusion capability of a new class of diffusers makes them suitable for most applications that require mechanically stretchable diffusers including flexible OLEDs and wearable strain sensors. Unlike the rigid diffusers, ,, these stretchable diffusers tune the distribution of light based on mechanically applied strain, while the recently developed diffuser as a sensor controls the light diffraction only based on a swelling behavior of hydrogel from chemicals . However, it has limited control over the light distribution pattern, generally making only linear patterns, but it is still suitable for both uniaxial and biaxial applied strains.…”

“…Optical diffusers are one of the most promising optical elements that can continuously process light beams directly and convey a diffraction of light for wearable biosensors, intraluminal photodynamic therapy, LEDs, and a wide variety of medical and electronic applications . Optical diffusers made from glass, plastic, or fiber are not flexible, stretchable, soft, or super-hydrophobic devices , and have therefore gained significant attention. In contrast, the recent development of an optical diffuser based on a hydrogel film has provided the possibility of meeting these requirements for a stretchable element .…”

Tunable Optical Diffusers Based on the UV/Ozone-Assisted Self-Wrinkling of Thermal-Cured Polymer Films

“…Artificial optical diffusers, which are generally made from non-deformable rigid materials, have always been significant parts in many photonics and optoelectronics systems [ 1 , 2 , 3 ]. For example, liquid crystal displays (LCDs) could effectively reduce the light intensity of LEDs and make the illumination effect more uniform [ 4 , 5 , 6 ].…”

Conformable Holographic Photonic Ink Sensors Based on Adhesive Tapes for Strain Measurements

“…Nevertheless, integrating nanoscale features over commercial tape represents an essential challenge. Convential nanofabrication methods are able to form optical structures; however, they are costly and time consuming [21][22][23] . Methods such as contact stamping, micro molding, E-beam processing, and ultrashort laser pulse lithography can be used to fabricate nanostructures on a tape [24][25][26] .…”