Tunable sub-300 fs soliton and switchable dual-wavelength pulse generation from a mode-locked fiber oscillator around 2.8 µm
Hongyu Luo, Jian Yang, Jianfeng Li, Yong Liu
Abstract
In this Letter, we demonstrate, for the first time, to the best of our knowledge, tunable soliton and switchable dual-wavelength pulse generation from a nonlinear polarization rotation mode-locked <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">E</mml:mi> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>3</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> -doped fluoride fiber oscillator around 2.8 µm, employing a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">L</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> <mml:mi mathvariant="normal">N</mml:mi> <mml:mi mathvariant="normal">b</mml:mi> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> birefringent plate (BFP)-based Lyot filter. In the single soliton state, the wavelength can be continuously tuned in the region of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>2752.4</mml:mn> </mml:mrow> <mml:mo>∼</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>2807.2</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∼</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>55</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> ) with a pulse width between 199 and 270 fs, by rotating the BFP with the aid of its spectral filtering effect. At higher pump levels, two kinds of dual-wavelength synchronous mode-locking states (i.e., 2746.4/2782.0 and 2787.2/2825.2 nm) are observed, and can be flexibly switched by adjusting the rotation angle of the BFP. This approach opens up new opportunities for the development of versatile mid-infrared ultrashort laser sources.