Silicon nitride PIC-based multi-color laser engines for life science applications

Abstract

We implement a multi-color laser engine with silicon nitride photonic integrated circuit technology, that combines four fluorophore excitation wavelengths (405 nm, 488 nm, 561 nm, 640 nm) and splits them with variable attenuation among two output fibers used for different microscope imaging modalities. With the help of photonic integrated circuit technology, the volume of the multi-color laser engine’s optics is reduced by two orders of magnitude compared to its commercially available discrete optics counterpart. Light multiplexing is implemented by means of a directional coupler based device and variable optical attenuation as well as fiber switching with thermally actuated Mach-Zehnder interferometers. Total insertion losses from lasers to output fibers are in the order of 6 dB at 488 nm, 561 nm, and 640 nm. Higher insertion losses at 405 nm can be further improved on. In addition to the system level results, spectrally resolved performance has been characterized for each of the developed devices.

Integrated Photonics Packaging: Challenges and Opportunities

“…A cohort of packaging techniques have already been adapted to the visible, for example, on the SiN-based TriPlex platform. − Fiber-optic connections to PICs are established using methods similar to those employed for near-IR bands, albeit with tighter alignment tolerances due to the wavelength scaling. Alternatively, visible PICs can also interface directly with free space via polished end facets or etched 45° mirrors …”

“…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 …”

“…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 ).…”

Power-Efficient Silicon Nitride Thermo-Optic Phase Shifters for Visible Light

“…Integrated photonics for visible wavelengths is becoming the focus of a growing number of research efforts in recent years [1][2][3][4][5][6][7]. By adapting the tools and fabrication infrastructure developed for silicon (Si) photonics at telecommunication wavelengths, visible-light photonic circuits with ∼ 10 -100's of components have been demonstrated for neurophotonics [6,8], beam scanners [9], and quantum information [10,11] applications.…”

Hybrid-integrated diode laser in the visible spectral range

“…The concept of hybrid-integrated diode lasers with very small intrinsic linewidths could possibly cover the whole visible spectral range. Realization of a fully integrated multi-color visible laser engine [28] would then become feasible for numerous applications.…”