  Monolayer transition metal dichalcogenides with direct bandgaps are emerging
candidates for microelectronics, nano-photonics, and optoelectronics.
Transferred onto photonic integrated circuits (PICs), these semiconductor
materials have enabled new classes of light-emitting diodes, modulators and
photodetectors, that could be amenable to wafer-scale manufacturing. For
integrated photonic devices, the optical losses of the PICs are critical. In
contrast to silicon, silicon nitride (Si3N4) has emerged as a low-loss
integrated platform with a wide transparency window from ultraviolet to
mid-infrared and absence of two-photon absorption at telecommunication bands.
Moreover, it is suitable for nonlinear integrated photonics due to its high
Kerr nonlinearity and high-power handing capability. These features of Si3N4
are intrinsically beneficial for nanophotonics and optoelectronics
applications. Here we report a low-loss integrated platform incorporating
monolayer molybdenum ditelluride (1L-MoTe2) with Si3N4 photonic
microresonators. We show that, with the 1L-MoTe2, microresonator quality
factors exceeding 3 million in the telecommunication O-band to E-band are
maintained. We further investigate the change of microresonator dispersion and
resonance shift due to the presence of 1L-MoTe2, and extrapolate the optical
loss introduced by 1L-MoTe2 in the telecommunication bands, out of the
excitonic transition region. Our work presents a key step for low-loss, hybrid
PICs with layered semiconductors without using heterogeneous wafer bonding.
