August 18, 2020

On-chip 3D printing of hollow-core photonic waveguides

An international research team presents a novel concept of an on-chip light cage that confines and guides light diffraction-free over centimeter distances. Using Nanoscribe’s 3D printers, the scientists fabricated hollow-core 3D photonic waveguides directly on a silicon photonic chip. The microscopic structure consists of finest strands arranged in two rings around a hollow core. Together with the integration on the chip, the strong light-matter interaction possible in this light cage opens up new applications. This innovation is particularly promising for gas and liquid-based detection as well as for bioanalytics and quantum technology.

3D hollow-core dual-ring light cages
Rendered image of 3D hollow-core dual-ring light cages for light guidance over centimeter distances. Image: Bumjoon Jang, Leibniz Institute of Photonic Technology

The strong interaction of light with gases, liquids or biological agents in integrated photonic devices enables novel methods and mobile applications in environmental monitoring and biosensors. Advanced optical sensing elements are needed to enhance strong light-matter interaction. With this goal in mind, a team of scientists from the Leibniz Institute of Photonic Technology, the Ludwig-Maximilians-Universität Munich, the Imperial College London and the Otto Schott Institute of Materials Research of the Friedrich Schiller University of Jena develops a new waveguide concept of a 3D light cage. The waveguide traps light behind microscopic bars and guides it over distances of many millimeters by means of the photonic band gap effect. The open design of the light cage is advantageous for strong interactions between light and matter, such as liquids or gas molecules.

3D Microfabrication of photonic waveguides

To fabricate this challenging microscopic structure, the scientists print the dual-ring light cages directly on a silicon chip by means of Nanoscribe’s 3D Microfabrication technology. The complex architecture consists of two rings with strands arranged hexagonally around a hollow core where the light is guided. The extremely fine strands have a diameter of 3.6 µm, a pitch between the strands of 7 µm and a length of 5 millimeters, reaching a high aspect ratio of more than 1,000.

The 3D microstructure design allows lateral access to the core regions of the waveguide through the open spaces between the strands. Consequently, molecules can enter the hollow core from the side and interact with the light in the core area. Performance tests demonstrate efficient waveguiding through the 3D light cage. Moreover, chip integration makes the light cage concept attractive for a number of fields such as bioanalytics or quantum technology. According to the above-mentioned research team, the length of the waveguide has reached up to 3 cm, yielding an aspect ratio higher than 8,000.

Further photonic materials by additive manufacturing

Nanoscribe’s 3D Microfabrication technology drives research and innovation in photonic circuits thanks to its 3D printing capabilities of extremely complex and high-precision microparts. In addition, the concept of direct laser writing enables the production of intricate 3D microparts directly on a photonic chip. The realization of 3D photonic crystals, photonic interconnects, as well as compound lens systems and freeform couplers are important achievements realized by means of Nanoscribe’s 3D printers.

Read the full scientific publications here:
Light guidance in photonic band gap guiding dual-ring light cages implemented by direct laser writing
Hollow Core Light Cage: Trapping Light Behind Bars

These publications and further scientific publications on hundreds of research projects can be found in a powerful database with an underpinned keyword search in the Premium Resources section. Register for free and gain insights into the potential of Nanoscribe’s 3D Microfabrication technology for innovative applications and fundamental innovations in many areas.

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