JOM Associate Editor Dr. Hui Min Leung of Harvard Medical School and Massachusetts General Hospital interviews Dr. Guillermo (Gary) Tearney, the Remondi Family Endowed MGH Research Institute Chair, Professor of Pathology at Harvard Medical School, and an Affiliated Faculty member of the Harvard-MIT Division of Health Sciences and Technology. He maintains a lab at the Wellman Center for Photomedicine at the Massachusetts General Hospital. With the use of advanced endomicroscopy technologies, Tearney’s lab performs development and clinical validation of non-invasive, high-resolution optical imaging methods for human disease diagnosis. Through this interview, he described how he got into the field and how important and relevant optical microsystems are to those research projects. He also gave his thoughts on the future of the field and the grand challenges that remain to be tackled.

Ridge waveguides were three-dimensional printed using a stereolithography printer and hydrogel resin formulation. The ridge waveguides were 13, 20, and 30 μm wide, 3 to 6 μm high, and 4.4 mm long. The loss of the waveguides was measured using the cutback method and ranged between 0.28 and 1.2 cm ^{− 1} (or 1.2 and 5.2 dB / cm) with transmittances up to 0.94 (0.27 dB coupling loss) using 635 nm light. Our work demonstrates a quick and inexpensive method to fabricate integrated photonic chips with the promise to fabricate more complex photonic devices and systems.

Photonic add-drop filters are crucial components for the implementation of wavelength division multiplexing (WDM) in fiber-optic communication systems. The recent progress in photonic integration has shown the potential to integrate photonic add-drop filters alongside high-performance photonic building blocks on a chip to construct compact and complex photonic-integrated circuits for WDM. Typically, implementations are based on micro-ring resonators with integrated heaters or free carrier dispersion-based modulators to adjust the filter wavelength. However, heaters suffer from high power consumption, and free carriers result in optical absorption losses, limiting the scalability toward very-large-scale circuits. We demonstrate the design, simulation, fabrication, and experimental characterization of a compact add-drop filter based on a vertically movable, MEMS-actuated ring resonator. The MEMS-actuated add-drop filter is implemented in IMEC’s iSiPP50G silicon photonics platform and realized using a short post-processing flow to safely release the suspended MEMS structures in a wafer-level compatible process. The filter exhibits a through port linewidth of ∼1 nm (124.37 GHz) at 1557.1 nm, and it retains a port extinction of 20 dB and a port isolation of >50 dB under 27 V of actuation voltage. The combination of low-power consumption and a compact footprint demonstrates the suitability for very-large-scale integration in photonic circuits.

Various attempts have been discussed to overcome the lateral resolution limit and thus to enlarge the fields of application of optical interference microscopy. Microsphere-assisted microscopy and interferometry have proven that the imaging of structures well below Abbe’s resolution limit through near-field assistance is possible if microspheres are placed on the measured surface and utilized as near-field assisting imaging elements. The enhancement of the numerical aperture (NA) by the microspheres as well as photonic nanojets was identified to explain the resolution enhancement, but also whispering gallery modes and evanescent waves are assumed to have an influence. Up to now, to the best of our knowledge, there is no complete understanding of the underlying mechanisms and no model enabling to examine ideal imaging parameters. This contribution is intended to clarify how much the lateral resolution of an already highly resolving Linnik interferometer equipped with 100 × NA 0.9 objective lenses can be further improved by microspheres. Our simulation model developed so far is based on rigorous near-field calculations combined with the diffraction-limited illumination and imaging process in an interference microscope. Here, we extend the model with respect to microsphere-assisted interference microscopy providing a rigorous simulation of the scattered electric field directly above the sphere. Simulation and experimental results will be compared in the three-dimensional spatial frequency domain and discussed in context with ray-tracing computations to achieve an in-depth understanding of the underlying mechanism of resolution enhancement by the microsphere.