PhoenixD Laser Day 2022
Miniaturization opens up new possibilities for optical systems and their application fields like sensing and communication. The Optical Micro-Platform network within the cluster of excellence PhoenixD focusses on realizing a hybrid integrated optical chip. The goal is to demonstrate the combination of miniaturization and cost-efficient manufacturing of individual components, utilizing a customized automated system for the final step of precise optics assembly. Fig. 1 shows a concept for a manufacturing demonstrator of such a platform, based on an injection molded polymer chip with cavities for waveguides or optical fiber connections. Laser writing of electric contacts directly in the polymer poses effective integration of active components like photo- and laser diodes. Spectral functionalities like multiplexing, beam splitting and wavelength filtering are realized by custom miniaturized thin-film interference components. These multilayer thin-films are deposite d in a specialized ion beam sputtering (IBS) process. The IBS process is in situ controlled by a high-resolution broadband monitor, retaining high layer thickness accuracy, even for complex designs with narrow spectral features. Afterwards, the coating is laser cut into miniaturized elements which fit into grooves on the micro-platform. For the case of transmission through such a thin-film component on the platform, the thickness of the element is crucial. To increase coupling efficiency to the subsequent waveguide without using micro-lenses, we have developed substrate-free thin-films . Fig. 1: Sketch of the Optical Micro-Platform with an integrated substrate-free miniaturized thin-film element. Switches, respectively laser modulators are an interesting module for the Optical Micro-Platform demonstrator. Due to the advantageous integration of electrical contacts directly on the optical micro-platform, the electro-optic effect is a suitable mechanism to realize active spectral manipulation. The integration of layers of novel crystal-like materials between IBS thin-film mirrors is to be exploited for this purpose. These materials are developed by partners within PhoenixD and show promising characteristics regarding electro-optic refractive index change as well as cost-efficient manufacturing, while addressing a different wavelength range than silicon photonics, exhibiting transmission in the visible to near infrared.  A. K. Rüsseler, F. Carstens, L. Jensen, S. Bengsch, and D. Ristau, "Applying sacrificial substrate technology to miniaturized precision optical thin-film coatings," Adv. Opt. Thin Films VII, Proc. SPIE 11872, 48–55 (2021).