Recently, Jie Zhou and Associate Professor Wei Zhang et al., with Qingyang Du from MIT as co-author, have investigated the chalcogenide waveguides and micro-ring resonators, which has been published in IEEE Journal of Selected Topics in Quantum Electronics, entitled “Large Nonlinearity, Low Loss Ge-Sb-Se Glass Photonic Devices in Near Infrared”.
Chalcogenide waveguides are considered as promising candidates for applications in biochemical sensing, integrated photonics, and ultrafast all-optical signal processing. In this study, Ge28Sb12Se60 waveguides and microresonators were fabricated by thermal evaporation and dry etching technology. The low loss waveguides and high-index-contrast Ge28Sb12Se60 microring resonators were developed and demonstrated using the optimal parameters of CF4 /CHF3 etching recipe, and the lowest surface RMS roughness of the waveguide was only 0.67 nm (shown in Figure 1). An intrinsic quality factor (Q-factor) of 2.3 × 105 with propagation loss of 2.4 dB/cm at 1550 nm was obtained in this microring resonator with 800 × 400 nm cross-sectional dimension. Critically coupled resonator showed extinction ratio of >30 dB (shown in figure 2). Nonlinear refractive index (n2) of 5.12×10−18 m2 /W for Ge28Sb12Se60 glass was measured and nonlinear coefﬁcient (γ) of 24 W−1m−1 as fabricated waveguide was also estimated. This paper illustrates the potential of Ge28Sb12Se60 glass as a low loss and large nonlinearity material for integrated photonics applications.
Fig.1 (a) SEM images of waveguides with 2, 4, 6, and 8 μm.
(b) SPM surface morphologies of 6 m wide waveguide
Fig. 2 (a) Top view optical microscope image of 40 m radius microring resonator.
(b) Experimental data of spectrum (red points) and the curve ﬁtting (blue solid line)
of one resonant peak of Optical transmission spectrum