Superior Temperature-Sensing Performance in Cladding-Modulated Si Waveguide Gratings

This paper presents a silicon photonic temperature sensor based on a complementary metal-oxide-semiconductor (CMOS) compatible cladding-modulated (CladMod) grating design on the silicon-on-insulator platform. The resulting device achieves narrow-band reflection (Δλ = 0.63 nm), a high extinction ratio (21 dB), high temperature sensitivity (83.4 pm/°C), and a wide temperature-sensing range. More importantly, this grating design allows stable reflection bandwidth (Δλ/ΔW
_g
= 0.013), Bragg wavelength (λ
_B
/ΔW
_g
= 0.002), and temperature sensitivity (δλ /δT/ΔW
_g
= -1.3 × 10
^-5
K
^-1
) against variations in grating width. This level of temperature-sensing performance is difficult to achieve using a strip/slab-type grating or microring resonator. The CladMod gratings were further implemented on a polysilicon gate in a standard bulk CMOS process, thereby enabling integration with other microelectronic devices to serve as an on-chip distributed temperature-sensing element This approach shows considerable promise for applications such as future photonic-electronic integrated circuits requiring in situ temperature monitoring for wavelength stabilization, or high-temperature microelectronics where silicon bandgap temperature sensors are unable to operate properly.