Highly efficient and compact acousto-optic modulator of a fibre Bragg grating is reported for the first time. The device is composed of millimetre scaled components and a 1 cm grating inscribed in a four air holes birefringent suspended core fibre. The reflection of the orthogonal polarization modes is tuned by a sinusoidal electrical signal at the resonance frequency of 469 kHz. A significant modulation depth of 45% is achieved at a maximum drive voltage of 10 V. The demonstrated 4 cm long all-fibre modulator is 60% shorter compared to previous similar setups, indicating new possibilities for stable and fast switching of fibre-integrated photonic devices
