Free-form micro-optics enabling ultra-broadband low-loss fiber-to-chip coupling

(Invited) From Lab to Fab: The Journey of Waveguide-Enhanced Raman Spectroscopy

“…First, switching to TM strip waveguides from TE slot waveguides would improve the output Raman signal as well as more effectively remove the pump source, increasing the SNR in the process. Second, better inverse taper couplers and packaging methods would increase the coupling efficiency to the waveguides, which would result in an improved SNR [57][58][59] . Third, lowering the transmitted pump light and fiber background would result from removing all elements that cause back-reflection.…”

Integrated Photonics Packaging: Challenges and Opportunities

“…76−78 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. 79,80 Channel density is largely dictated by the coupling configuration (edge vs surface-normal coupling) and to a lesser extent the on-chip footprint of the coupler structures. Edge coupling can only access the periphery of a chip, whereas surface-normal coupling can make use of dense 2D coupler arrays to maximize the channel density.…”

“…For the same reason, surface-normal coupling is suited for wafer-level testing prior to dicing while edge coupling is only available after individual chip singulation, or alternatively requires specialty designed fiber probes. 81 In addition to the four main metrics, manufacturability, scalability, and compatibility with standard electronic packaging protocols (e.g., solder thermal reflow treatment 80 ) are among other considerations that should be accounted for. Figure 1 presents a radar chart comparing several optical coupling technologies based on these metrics.…”

“…Besides refractive microlenses, reflective micro-optics can be similarly adapted for this purpose. 44,80 Reliability. PICs and their packages must fulfill applicationspecific industry standards on reliability.…”