Free-Form Micro-Optical Reflectors for Broadband and Low-Loss Fiber-to-Chip Coupling

Abstract

We demonstrate a novel fiber-to-chip coupling scheme based on surface-normal free-form micro-reflectors 3D-printed onto SiNx waveguide facets. Insertion losses of 0.5 dB and 1 dB bandwidth exceeding 300 nm were measured at 1550 nm wavelength.

Integrated Photonics Packaging: Challenges and Opportunities

“…In addition to the four main metrics, manufacturability, scalability, and compatibility with standard electronic packaging protocols (e.g., solder thermal reflow treatment) are among other considerations that should be accounted for. Figure presents a radar chart comparing several optical coupling technologies based on these metrics.…”

“…However, as they still suffer from shoreline density problem, future connectors will be designed to be compatible with surface mount technology (SMT) packaging, thereby leveraging the economy of scale in standard electronics packaging. Besides refractive microlenses, reflective micro-optics can be similarly adapted for this purpose. , …”

“…Grating couplers, while capable of attaining close-to-unity coupling efficiency at a single wavelength, , are inherently wavelength sensitive: , even though designs with enlarged bandwidths have been theoretically proposed, , they mandate design constraints not consistent with standard integrated photonics platforms. Conversely, the wavelength sensitivity of grating couplers may be exploited for spectral (de)­multiplexing. − Micro-optical refractive and reflective coupling interfaces, on the other hand, can claim remarkable octave-spanning performance given the weak wavelength dependence of optical refraction and reflection versus diffraction. , …”

“…On processing compatibility, the coupling schemes are categorized into three classes: fully compatible with standard foundry manufacturing without any process customization; in principle compatible with standard foundry fabrication although custom process steps are needed; and new processes and materials are involved. Data cited from refs (standard grating/edge couplers), (grating coupler with Si removal), (edge coupling with multilayer nitride), (photonic plug), (photonic wire), (OFFCHIP), and (evanescent coupling). The bandwidth for the photonic wires is estimated based on ref .…”