Improved All-Fiber Acousto-Optic Tunable Bandpass Filter

Abstract

Abstract-An all-fiber acousto-optic tunable bandpass filter based on a 1.185-mm long coreless core mode blocker is reported. Experimental results demonstrate a minimal insertion loss of 1.2 dB at the optical resonant wavelength of 1527.7 nm with 3-dB optical bandwidth of 0.83 nm. The optimization of the device takes into account the attenuation of the acoustic wave and leads to an asymmetric configuration in which the coupling section is shorter than the recoupling part. Under the effect of a standing flexural wave the device can be operated as a bandpass modulator. The device exhibits a maximum modulation depth of 28 %, 4 dB of insertion loss and 0.97 nm of optical bandwidth at 4.774 MHz.Index Terms-Acousto-optic filters, acousto-optic modulation, bandpass filters.

Q-switching and mode locking pulse generation from an all-fiber ring laser by intermodal acousto-optic bandpass modulation

“…In the framework of QML all-fiber lasers, the development of efficient in-fiber modulators is of great interest. In the past few years, there have been many efforts in this direction, and a few in-fiber approaches have been reported [23][24][25][26][27][28][29]. In this regard, our group has previously investigated a novel type of in-fiber acousto-optic (AO) tunable bandpass modulator, whose operation principle relies on full-acousto-optic mode re-coupling cycle induced by flexural acoustic waves.…”

Q-switching of an all-fiber ring laser based on in-fiber acousto-optic bandpass modulator

“…Under this scheme the device operates as a bandpass filter, and wavelengths that do not fulfill the phase-matching condition are strongly attenuated. By following a similar process to that reported in reference [20], the response of the AOTBF is optimized with an asymmetric configuration that takes into account the attenuation of the acoustic wave. For the set of experiments reported here, the length of section L 2 was adjusted to find the optimal interaction length for a maximum reinsertion of energy in the 1550 nm region.…”

“…In this respect, in-fiber acousto-optic (AO) devices can be designed to perform a bandpass operation with a widely tunable spectral response [15][16][17][18][19]. In a previous work, we reported the operation of an efficient all-fiber acousto-optic tunable bandpass filter (AOTBF) that combines the dynamic properties of flexural acoustic waves with a fiber core-mode blocker (CMB) [20]. With the objective of expanding the application of the AOTBF to perform active Q-switching, the acoustic wave is modulated by a rectangular pulse of variable repetition frequency and duty cycle.…”

Actively mode-locked all-fiber laser by 5 MHz transmittance modulation of an acousto-optic tunable bandpass filter

“…This condition has motivated the improvement of active mode lockers to eliminate the inclusion of filtering devices in the laser cavity. In this regard, in-fiber AO devices can be designed to realize a bandpass operation with a widely tunable spectral response [5,[15][16][17]. In previous publications we have reported the operation of an efficient in-fiber AO tunable bandpass filter (AOTBF) that combines the dynamical properties of flexural acoustic waves together with a core mode blocker (CMB) composed of a tiny section of coreless optical fiber [16,17].…”