Mode-locked all-fiber ring laser based on broad bandwidth in-fiber acousto-optic modulator

Abstract

Active mode-locking of long-cavity all-fiber ring laser based on broad bandwidth in-fiber acousto-optic modulator (AOM) is reported. The proposed AOM combines the advantages of intermodal coupling induced by standing flexural acoustic waves in a double-ended tapered fiber. We focus our attention on the effects of large tapered transitions to improve the bandwidth modulation. Our approach permits the implementation of broad modulation bandwidth (13 nm), high modulation depth (50 %), and low optical loss (1.1 dB) in an 80-lm configuration. The effects of the AOM in the laser performance are also investigated. Transform-limit optical pulses of 25 ps temporal width and 2.7 W peak power were obtained at 2.46 MHz repetition rate.

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

“…In addition to this, the time that the acoustic wave takes to travel along the modulator, around 222.6 s, can be regarded as a long period of time, having a direct impact on the Q switching and mode locking processes. In this respect, it is worth noting that some characteristics of the present device could be further improved by the inclusion of tapered optical fibers, resulting in a more efficient intermodal coupling [26] that leads to improved response times. Temporal characteristics of QML pulses as a function of the duty cycle are shown in figure 6(a).…”

“…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.…”

Recent progress of dynamic mode manipulation via acousto-optic interactions in few-mode fiber lasers: mechanism, device and applications

“…The pioneered discovery in 1986 that Kim et al firstly proposed and demonstrated the mode conversion with a frequency shift by a two-mode fiber-based AOMC [43], which has opened a door to novel researches on acousto-optic interactions (AOI) in fibers and various derived components. Among them, the most extensively concerned are tunable filters [51][52][53][54][55][56][57][58][59][60][61][62][63][64], super lattice modulations [65][66][67][68][69], heterodyne vibration detections [70][71][72][73], AOI in photonic crystal fibers (PCFs) [74][75][76][77], wavelength tunable lasers [78][79][80][81][82], ultrafast fiber lasers based on AOMCs [83][84][85][86][87][88][89][90][91][92], vector modes generations [93][94][95]...…”

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

“…In the framework of actively mode-locked lasers, many researchers have proposed and demonstrated different configurations to produce high-quality ultrashort optical pulses [3][4][5][6][7][8][9]. Among them, all-fiber arrangements are very attractive devices since they can reduce intracavity losses associated with bulk components and can be designed to adjust cavity dispersion simply by the inclusion of optical fibers with different group velocity dispersions.…”

“…One of the most common configurations of actively modelocked fiber lasers relies on the use of spectral filters to prevent laser emission at different wavelengths of the gain medium. Examples of these schemes can be found in [7][8][9][10][11][12][13][14], where active mode locking by using electro-optic modulators [7,8], in-fiber amplitude acousto-optic (AO) modulators [9][10][11], AO superlattice modulators [12,13] and conventional AO tunable filters [14] is reported. Therefore, a common shortcoming is the restriction of wavelength emission and the limited optical bandwidth.…”