Aluminium zinc oxide as a saturable absorber for passively Q-switched and mode-locked erbium-doped fiber laser

Abstract

Transparent conductive oxides (TCOs) are widely integrated in the field of optoelectronics since they are optically transparent and electrically conductive at the same time. Indium tin oxide (ITO) is a well-developed TCO, but due to its high cost, aluminum zinc oxide (AZO) is now emerging as a promising low-cost replacement for ITO. This work reports on AZO thin film prepared with polyvinyl alcohol (PVA) as a host material. The AZO–PVA thin film was incorporated into an erbium-doped fiber laser (EDFL) as a saturable absorber for the first time. Both Q-switched and nanosecond pulse mode-locked operation were experimentally achieved. The Q-switched EDFL operated at the center wavelength of 1559.6 nm, which had the shortest pulse width of 2.2 µs, the maximum repetition rate of 86 kHz and the highest pulse energy of 47.3 nJ. The mode-locked was achieved at the center wavelength of 1560.4 nm.

Mode-locked ytterbium-doped fiber laser with zinc phthalocyanine thin film saturable absorber

“…Including 50 m long SMF spool in the cavity increased net cavity dispersion which helped to achieve mode-locking instead of Q-switching [64,65]. A polarization controller (PC) was not added in this experimental setup as the interplay of cavity dispersion and the SA nonlinearity was sufficient to obtain mode-locking operation [66][67][68]. Hence, a PC was excluded from the experimental setup to avoid any additional insertion loss contribution from the PC.…”

A corrugated epsilon-nearzero saturable absorber for a high-performance 1.3 μm solid-state bulk laser

“…[25][26][27][28][29] Because of their low optical loss, good complementary metal oxide semiconductor (CMOS) compatibility, 19 high LIDT, strong environmental stability, ENZ-enhanced NLO response, and sub-picosecond response time, 18 TCOs have been demonstrated in various nonlinear optics applications, such as harmonic conversion, terahertz wave generation, and optical switching. [30][31][32][33] Currently, there are many reports about TCO-based SAs and their applications in ultrafast pulsed lasers. 19,[34][35][36] In 2017, Guo et al investigated the large optical nonlinearity of ITO nanocrystals (ITO NCs) and successfully demonstrated a fiber optical switch that allowed the switching of continuous laser waves into femtosecond laser pulses based on ENZ NCs at 1.55 μm.…”

“…19 Afterwards, the passively Q-switched solid-state lasers based on ITO nanowire arrays were demonstrated at 1.0, 1.3, and 2.0 μm. 36 The magnetron-sputtered ITO film and aluminum zinc oxide (AZO) thin film were used as SAs at 1.0 and 1.56 μm to generate fiber pulsed laser, 33,35 respectively.…”

Revealing the Evolution from Q-Switching to Mode-Locking in an Erbium-Doped Fiber Laser Using Tungsten Trioxide Saturable Absorber

“…One is introducing the nonlinear polarization evolution (NPE) effect to the fiber laser by using a polarization-dependent component, such as a polarizer [5], tapered fiber [6][7][8], or D-shaped fiber [9]. The other is dispersion management with significantly increased cavity length [10][11][12][13][14][15][16][17][18][19][20]; however, the repetition frequency of the laser is greatly reduced. In addition to the dispersion and nonlinearity, the parameters of the SA can also affect the performance of the QS and ML laser.…”