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

Abstract

Active Q-switching of an all-fiber ring laser by utilizing a novel in-fiber acousto-optic tunable bandpass filter (AOTBF) is reported. Transmission characteristics of the AOTBF are controlled by amplitude modulation of the acoustic wave, it exhibits a 3-dB power insertion loss, 0.91 nm of optical bandwidth, and 28 dB of nonresonant light suppression. Cavity loss modulation is achieved by full acousto-optic mode recoupling cycle induced by traveling flexural acoustic waves. When the acoustical signal is switched-on, cavity losses are reduced, and then laser emission is generated. Additionally, by changing the acoustic wave frequency, a wide wavelength tuning range of 30.7 nm is achieved from 1542 to 1572.7 nm. Best Q-switched pulses were obtained at 1.1 kHz repetition rate, with a pump power of 242 mW, at the optical wavelength of 1569.4 nm. A maximum pulse energy of 8.3 J at an average output power of 9.3 mW was achieved, corresponding to optical pulses of 7.8 W peak power and 1 μs temporal width.

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

“…The modulator consists on the same experimental arrangement described in Refs. [31,32]. Here, and for reasons of clarity, only the main transmission characteristics are described.…”

“…A schematic view of the AOM and its operation principle is shown in figure 1(b). The modulator consists on the same experimental arrangement described in [30,31]. Here, and for reasons of clarity, only the main transmission characteristics are described.…”

“…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. By using this AO device, Q-switched [31] and mode-locked [32] pulse operation was successfully obtained. Now, with the goal of producing a stable QML pulse emission, the modulator is operated to allow simultaneous emission of QML optical pulses.…”

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].…”

“…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]. Now, with the objective of expanding the application of the AOTBF to perform active mode locking, acoustic reflection is intentionally induced.…”