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Actively Mode Locked Raman Fiber Laser with Multimode LD Pumping

Authors :
Alexey G. Kuznetsov
Sergey I. Kablukov
Yuri A. Timirtdinov
Sergey A. Babin
Source :
Photonics, Vol 9, Iss 8, p 539 (2022)
Publication Year :
2022
Publisher :
MDPI AG, 2022.

Abstract

We present our recent experimental results on the pulsed regimes of Raman conversion of highly multimode laser diode (LD) pump radiation into the 1st and higher order Stokes radiation in multimode graded-index fibers. Three different linear cavities of Raman fiber laser with the modulation of losses (by acousto-optic modulator, AOM) or gain (by LD current) are explored and compared. An LD with wavelength of 976 nm is used for pumping enabling Raman lasing at wavelength of the 1st (1018 nm) and 2nd (1064 nm) Stokes orders. At ~27.2-kHz repetition rate corresponding to the laser cavity round-trip frequency (i.e., in the mode-locking regime), nanosecond pulses have been observed for both Stokes orders having the highest peak power of ~300 W in the scheme with bulk AOM and the shortest duration of 5–7 ns in the scheme with fiber-pigtailed AOM. At the same time, the beam quality of generated pulses is greatly improved as compared to that for pump diode (M2 > 20) reaching the best value (M2 = 2.05) for the 2nd order Stokes beam in the scheme with the gain modulation and demonstrating also the most stable regime.

Details

Language :
English
ISSN :
23046732
Volume :
9
Issue :
8
Database :
Directory of Open Access Journals
Journal :
Photonics
Publication Type :
Academic Journal
Accession number :
edsdoj.3097878c6ad44015a28bd06f12ad841f
Document Type :
article
Full Text :
https://doi.org/10.3390/photonics9080539