Acousto-optic modulation of a fiber Bragg grating in suspended core fiber for mode-locked all-fiber lasers

Abstract

The interaction of a fiber Bragg grating and longitudinal acoustic waves in a three-airholes suspended core fiber is experimentally investigated and employed to mode-lock an ytterbium-doped fiber laser. An optimized design of an acousto-optic modulator based on two piezoelectric transducers and 1 cm grating length is also proposed. For an electrical signal strength of 10 V applied to the modulator, the results indicate output pulses with a width of less than 550 ps at a repetition rate of 10 MHz. The reduction of the grating length and the power consumed by the transducer, when compared to previous studies, points out to more efficient, compact and fast acousto-optic modulators for mode-locked all-fiber lasers.

High frequency in-core acousto-optic modulation of a suspended core optical fibre

“…The experimental setup of the proposed device might require the simulation of the real SCFs geometry/material considering defects, imperfections or dimension changes along the fibre, which could shift the resonances and reduce the effective acoustic power in the core. Overall, the strong confinement of optical/acoustic powers in SCFs indicates a promising solution to modulate fibre lasers with repetition rates higher than 100 MHz (reflectivities higher than ηSCF = 1 % are already useful for laser operation 4 ). The acoustic wave is confined in the (a) silica bridges inducing a (b) periodic displacement/strain at the core centre along the fibre length (dashed red line in Fig.…”

“…The interaction of fibre Bragg gratings (FBGs) and longitudinal acoustic waves has been successfully employed in tuneable filters, Q-switched and mode-locked fibre lasers [1][2][3][4] . In particular, laser output properties, such as, power, wavelength, pulse width and repetition rate are electrically tuned by the frequency and power of the acoustic wave.…”

Ultra-compact acousto-optic modulator of a fibre Bragg grating in a highly birefringent suspended core fibre

“…In contrast, laser output properties, such as, power, wavelength, pulse width and repetition rate are electrically tuned by the frequency and power of all-fibre acousto-optic modulators. In particular, the interaction of fibre Bragg gratings (FBGs) and longitudinal acoustic waves has been successfully employed in multiwavelength tuneable filters, Q-switched and mode-locked fibre lasers [8][9][10][11][12][13] . A coaxial acousto-optic device is basically composed of a piezoelectric transducer (PZT), an acoustic silica horn and an optical fibre segment axially aligned.…”

Multi-wavelength reflection spectra from an acousto-optic modulated fiber Bragg grating in a highly birefringent suspended core fiber

“…On the other hand, the modulation of Bragg gratings by means of longitudinal acoustic waves enables the electrical and fast tuning of the grating reflectivity and wavelength, which is suitable for optical modulators, dynamic filters and fiber lasers [5,6]. Figure 1(a) illustrates the reflection spectrum of a non-perturbed FBG of period Λ.…”