Performance improvement of on-chip mid-infrared waveguide methane sensor using wavelet denoising and Savitzky-Golay filtering

•SOI ridge waveguide CH4 sensor was fabricated dry etching in mid-infrared.•WD and SG are combined for on-chip gas sensing signal denoising.•Detailed experiments are performed to verify the WD-SG denoising effect.•The LoD is reduced by 7.4 times using the WD-SG denoising scheme.