Al2O3:Yb3+ integrated microdisk laser label-free biosensor.

Whispering gallery mode resonator lasers hold the promise of an ultralow intrinsic limit of detection. However, the widespread use of these devices for biosensing applications has been hindered by the complexity and lack of robustness of the proposed configurations. In this work, we demonstrate biosensing with an integrated microdisk laser. Al2O3doped with Yb3+ was utilized because of its low optical losses as well as its emission in the range 1020-1050 nm, outside the absorption band of water. Single-mode laser emission was obtained at a wavelength of 1024 nm with a linewidth of 250 kHz while the microdisk cavity was submerged in water. A limit of detection of 300 pM (3.6 ng/ml) of the protein rhS100A4 in urine was experimentally demonstrated, showing the potential of the proposed devices for biosensing.

Low-loss, broadband and high fabrication tolerant vertically tapered optical couplers for monolithic integration of Si3N4 and polymer waveguides.

A low-loss, broadband and high fabrication tolerant optical coupler for the monolithic integration of Si3N4 and polymer waveguides is designed and experimentally demonstrated. The coupler is based on the adiabatic vertical tapering of the Si3N4 waveguides. Low-loss operation is experimentally verified at both 976 and 1460-1635 nm wavelengths. Measured losses per coupler are as low as 0.12 and 0.14 dB at 976 and 1550 nm, respectively, and below 0.2 dB at both wavelengths for lateral misalignments between the Si3N4 and polymer waveguides up to 1.0 µm.