Photonic integrated circuits for life sciences

Abstract

A large number of discrete optical components could be replaced by a photonic integrated circuit in a multi-color laser engine for the visible spectral range. The photonic integrated circuit is based on silicon nitride waveguide technology. We report on the use of silicon nitride (SiN) photonic integrated circuits (PICs) in high-value instrumentation, namely multi-color laser engines (MLEs), a core element of cutting-edge biophotonic systems applied to confocal microscopy, fluorescent microscopy - including super-resolution stimulated emission depletion (STED) microscopy - flow cytometry, optogenetics, genetic analysis and DNA sequencing, to name just a few. These have in common the selective optical excitation of molecules - fluorophores, or, in the case of optogenetics, light-gated ion channels - with laser radiation falling within their absorption spectrum. Unambiguous identification of molecules or cellular subsets often requires jointly analyzing fluorescent signals from several fluorescent markers, so that MLEs are required to provide excitation wavelengths for several commercially available biocompatible fluorophores. A number of functionalities are required from MLEs in addition to sourcing the required wavelengths: Variable attenuation and/or digital intensity modulation in the Hz to kHz range are required for a number of applications such as optical trapping, lifetime imaging, or fluorescence recovery after photobleaching (FRAP). Moreover, switching of the laser between two fiber outputs can be utilized for example to switch between scanning confocal microscopy and widefield illumination modes, for instance, for conventional fluorescence imaging.

Integrated Photonics Packaging: Challenges and Opportunities

“…Alternatively, visible PICs can also interface directly with free space via polished end facets or etched 45° mirrors Figure illustrates a visible PIC equipped with both fiber-optic and free-space optical interfaces designed to operate as a multicolor laser engine for applications in life sciences. , Light source integration has also been realized, via grating coupling to VCSELs and butt coupling to III–V gain chips …”

“…Reprinted, with permission, from refs and . Copyright 2021 The Optical Society (ref ) and Copyright 2020 The Author(s) (ref ).…”

“…A SiN PIC transmitting four visible colors with a fiber-optic connection and free-space interfaces. Reprinted, with permission, from refs and . Copyright 2021 The Optical Society (ref ) and Copyright 2020 The Author(s) (ref ).…”