Ultra-short phase-shifted fiber Bragg grating in a microprobe for refractive index sensor with temperature compensation

•An Ultra-short phase-shifted fiber Bragg grating composed of cascaded microchannels in the silica-microprobe is first proposed.•The cascaded microchannels are etched in the microprobe and a fiber Bragg grating is written in the core of single-mode fiber near the microprobe.•The length of the microprobe is less than 150 μm, and the total length of the ultra-short PS-FBG is less than 95 μm.•Experimental results show that the RI sensitivity of the PS-FBG is 463.7953 nm/RIU in the range of 1.3323 ∼ 1.3797.