Scientists have developed a new method of 3D photoshaper with high efficiency and accuracy

Modern technologies such as optical computing, integrated photonics and digital holography all require flexible manipulation of optical signals in three-dimensional space. In this process, it is crucial to shape and direct the flow of light according to its desired application.

Because the optical flow in the medium is controlled by the refractive index, the refractive index needs to be tailored specifically to achieve the control of the optical path in the medium. To this end, scientists have developed so-called aperiodic photon volume elements (APVEs), which are microscopic voxels with a specific refractive index that are positioned to direct the flow of light in a controlled manner. However, sculpting these elements requires a high degree of precision, and most light-shaped materials are limited to 2D configurations or ultimately reduce the output beam profile.

Recently, in a study published in the photonics journal APNexus, researchers led by Alexander Jesacher of the Medical University of Innsbruck in Austria propose a simple way to make high-precision APVEs and use them in a range of applications. This method breaks the limitation of photoforming mentioned above.

The method uses an ultra-fast laser technique called direct laser writing to arrange voxels of a specific refractive index in 3D inside borosilicate glass to precisely direct light for a variety of applications.

The researchers devised an algorithm that stimulates light through the medium to determine the optimal position of the voxel to achieve the necessary precision. Based on this, they were able to produce 154,000 to 308,000 voxelins in 20 minutes, each with a volume of about 1.75 μm × 7.5 μm × 10 μm. In addition, they use dynamic wavefront control to compensate for any spherical aberrations (beam profile distortions) during which the laser is focused on the substrate. This ensures the consistency of each voxel profile at all depths in the medium.

The team developed three types of APVEs to demonstrate the applicability of the method: an intensity shaper to control the intensity distribution of the input beam, an RGB multiplexer to control the transmission of the input beam's red, green and blue (RGB) spectrum, and a Hermite-Gaussian (HG) mode sorter to improve data transmission speeds.

The team used an intensity shaper to convert a Gaussian beam into a microscopic smile-arc light distribution, then a multiplexer to represent different parts of the smile-arc distribution in different colors, and finally a HG mode sorter to convert multiple Gaussian mode inputs delivered by the fiber into HG mode. In all cases, the device was able to transmit the input signal without significant loss and achieved a record diffraction efficiency of up to 80%, setting a new benchmark for the APVEs standard.

This new approach could open the door to an ideal low-cost platform for rapid prototyping of highly integrated 3D photoformers. In addition to its simplicity, low cost and high accuracy, the method may be extended to other substrates, including nonlinear materials. Its flexibility makes it suitable for designing a wide range of 3D devices for information transmission, optical computing, multi-mode fiber imaging, nonlinear photonics and quantum optics.

Source: OFweek