Scientists develop 2.5D inkjet printing technology for manufacturing precision optical components

Many breakthroughs have been made in optical 3D printing, and researchers in Switzerland are now introducing new breakthroughs. The team from the Swiss Centre for Electronics and Microtechnologies (CSEM) has developed inkjet printing technology for the manufacture of precision optical components, such as by limiting the wave The extension (abbreviation 'waveguide') allows the signal to propagate without causing a large amount of energy loss.

But there is a problem here. In fact this method is considered to be 2.5D printing, rather than 3D printing, because the printing structure is not flat, but the complexity is limited compared to 3D printing. 'Inkjet printing is the manufacture of optical components A very attractive method, because the position and size of the features can be easily modified, and there is almost no material wasted. However, the surface tension of the ink makes it difficult to print lines with a certain height, which forms a 'waveguide' It is required,' said Fabian Lütolf, member of the CSEM team.

Inkjet printing is usually a one-step process by depositing a pattern of droplets onto a substrate through tiny nozzles. However, the CSEM team found that lines can print smoother features and deposit ink at two levels in a specific height. Their technology Can print 2.5D optical waveguides and cones made from acrylic polymers, as well as other materials such as metallic inks. Pius M. Theiler, now at the Zurich Federal Institute of Technology Lütolf and team leader Rolando Ferrini, published in the Optics Express journal Paper entitled "Contactless Printing of Optical Waveguides Using Capillary Bridges".

Due to the surface tension of the liquid, the ink deposited on the substrate may crack or bulge. But this two-step method can turn this problem into an advantage. The ink printed in step #2 can be printed on the first ink drop Align themselves to reduce their surface tension. This also means that researchers do not have to pattern-print the substrate beforehand, which is necessary for other inkjet printing technologies, which makes the manufacture easier and increases the available Design space.

The new technology first prints a series of spherical droplets, called caps, and then staples the liquid bridge made of the second photo ink. This droplet configuration prevents the ink from moving, thus preventing the formation of protrusions on the printing line. This method can also connect multiple connection points to form sharp edges and corners. Compared with traditional lithography, it also has several advantages. It is often used to fabricate tiny components on a chip. Researchers use inkjet printing methods. Create the waveguide. The laser (wavelength) is sent through the waveguide to measure the optical properties of the waveguide. Lütolf explains: 'Inkjet printing does not require physical masks such as photolithography, and connecting components is easier. Also, if you only want fast To test an idea or change parameters, additive manufacturing methods such as inkjet printing need only be adapted to digital design.

According to the theoretical calculation of the new two-step inkjet printing method (hn) and its actual printing (ou), the printing characteristics were compared with standard one-step inkjet printing (ag). Scale bar = 200 microns. The team created a width of 20 A micron, 31-micron-high polymer waveguide with a tapered shape to allow light from an external laser to enter the waveguide to evaluate the new method. The optical loss within the waveguide is measured to be 0.19 dB/cm, which is only better than photolithography The waveguide is an order of magnitude higher.

In this paper, we report the first inkjet printed waveguides with loss characterization. For our envisaged applications, waveguides will transmit light over short distances, rather than transmitting light throughout the network,' says Lütolf. The current level of loss can be tolerated for this application. The smallest waveguide consists of a single drop, and its size is limited by the nozzle of the printer. However, in their study, the narrowest waveguide size of the printer was 40 microns and the height was approximately 10 microns, which is similar to the performance of industrial inkjet printers used in the market. With our current combination of materials and hardware, it is not possible to make waveguides below 10 microns, which is usually necessary for single mode operation. But we are very close. However, , No basic physical restrictions will prevent us from printing single-mode waveguides.

Source: China 3D Printing Network