Open AccessRaman amplification of optical beam carrying orbital angular momentum in a multimode step-index fiber
Author(s) -
Shankar Pidishety,
Shining Zhu,
Yutong Feng,
Balaji Srinivasan,
Johan Nilsson
Publication year - 2019
Publication title -
optics letters/optics index
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.524
H-Index - 272
eISSN - 1071-2763
pISSN - 0146-9592
DOI - 10.1364/ol.44.001658
Subject(s) - optics , materials science , multi mode optical fiber , raman spectroscopy , raman scattering , polarization maintaining optical fiber , optical amplifier , double clad fiber , optical fiber , fiber optic sensor , physics , laser
We experimentally demonstrate 15 dB of Raman amplification of 1115 nm pulses in an orbital angular momentum mode (OAMM) with charge l=+2, S=+1 in 5 m of step-index 25 μm-diameter-core fiber. The total output reaches 4.5 kW of peak power and 68.5 μJ of energy in ∼15 ns pulses at 4 kHz repetition rate. An Yb-doped fiber source pumps the Raman amplifier at 1060 nm with 60 ns pulses. Using a spatial light modulator for modal decomposition, we measure 83% purity for the amplified target OAMM of selected polarization. To the best of our knowledge, this is the first time high energy, peak power, gain, and purity are achieved in a fiber Raman amplifier for a single OAMM.