Page 67 - rise 2017

10
-10
Output power (dBm) -30 SNR=59.89dB

-50

-70
-90

-110
0 200 400 600 800 1000
Frequency (kHz)

Figure 6: RF spectrum of the Q-switching pulse at pump power of 96 mW

The proposed laser is observed to be highly stable, with no significant changes observed in any of the
output parameters after two hours of operation, and repeated cycles of operation in the two days
following. When the pump power was over 96 mW, the Q-switched pulses became unstable and
switched to CW mode, as usually observed in some passively Q-switched fiber lasers reported
previously [6-8]. It is expected that a better Q-switched pulse can be obtained by optimizing the
design of the cavity, including reducing the cavity length and cavity losses as well as optimizing its
cavity structure and using higher quality GO based SAs.

Conclusion
We have demonstrated a passively Q-switched EDFL based on GO PVA SA. The SA device is
fabricated by embedding a GO material into PVA film. Employing this device into an EDFL cavity,
we have achieved stable Q-switched pulses generation. It operates at 1563.3 nm within a pump power
range of 39 to 96 mW. Through fine increasing the pump power, the repetition rate could be changed
from 44.33 kHz to 61.77 kHz, and pulse duration from 9.51 µs narrow to 5.57 µs. The pulse energy
was 0.054 nJ at pump power of 96 mW. These results shows that GO is a new potential SA material
for pulsed laser applications.

References
[1] O. L. Antipov, N. G. Zakharov, M. Fedorov, N. M. Shakhova, N. N. Prodanets, L. B. Snopova, V.
V. Sharkov, R. Sroka, “Cutting effects induced by 2μm laser radiation of cw Tm:YLF and cw and Q-
switched Ho:YAG lasers on ex-vivo tissue,” Med. Laser Appl., 26(2), pp. 67-75, 2011.
[2] G. D. Spiers, R. T. Menzies, J. Jacob, L. E. Christensen, M. W. Phillips, Y. Choi, E. V. Browell,
Atmospheric CO2 measurements with a 2μm airborne laser absorption spectrometer employing
coherent detection, Appl. Opt. 50(14), p. 2098-2111, 2011.
[3] Delgado-Pinar, M., D. Zalvidea, A. Díez, P. Pérez-Millán and M. V. Andrés, “Q-switching of an
all-fiber laser by acousto-optic modulation of a fiber Bragg grating,” Optics express, 14(3), pp. 1106-
1112, 2006.
[4] M. B. Hisyam, M. F. Rusdi, A. A. Latiff, and S. W. Harun, “PMMA-doped CdSe quantum dots as
saturable absorber in a Q-switched all-fiber laser,” Chinese Optics Letters, 14(8), pp. 081404-81408,
2016
[5] H. –Y. Wang, W. –C. Xu, A. –P. Luo, J. –L. Dong, W. –J. Cao, L. –Y. Wang, “Controllable
dissipative soliton and Q-switched pulse emission in a normal dispersion fiber laser using SESAM
and cavity loss tuning mechanism,” Optics Communications, 285(7), pp. 1905-1907, 2012.