The invention relates to a pH value sensor based on a tilted
fiber Bragg
grating girdle amplification
welding technology. The pH value sensor is based on the principles that the
refractive index of a pH sensitive film is modulated by liquid pH value, the reflected
cladding mode is regulated by the external
refractive index and the Bragg reflection mode is not modulated by the external
refractive index, and prepared by the girdle amplification
welding technology. The pH value sensor comprises a
broadband light source, a coupler, a tilted
fiber Bragg
grating, the pH sensitive film, and a
photodiode. The
cladding mode returned from the tilted
fiber Bragg
grating is performed with the girdle amplification
welding technology, then transmitted by
optical fiber core, converted into analog electric signals, and introduced into a
data processing module; the strength of the
cladding mode is measured to obtain the refractive index of the pH sensitive film, so as to obtain the pH value. The pH value sensor adopts the theory that the external temperature change only influences the
wavelength of the reflective spectrum to drift within a
small range, so that the influence to the measurement from the temperature change can be effectively avoided. At the same time, due to the characteristic that the Bragg reflection mode of the tilted
fiber Bragg grating is not influenced by the external refractive index, the influence of the
broadband light source fluctuation to the
pH measurement result can be avoided.