Mode-Locking Dynamics in an All-PM Figure-Nine Tm-Doped Fiber Laser

Abstract

We report a study on pulse dynamics in figure-nine Tm-doped all-polarization maintaining fiber laser. We analyzed laser operation from self-starting with multi-pulse dynamic to single-pulse operation by decreasing the pump power from the mode-locking threshold. By choosing a reliable setting of waveplates, our laser was generating pulses at the central wavelength of 1985 nm with a half-width of the spectrum, pulse duration, and pulse energy equal 6.4 nm, 650 fs, 177 pJ for the output port and 19.2 nm, 1279 fs, 57 pJ for the reject port in the single-pulse state. In the multi-pulse state, we recorded optical spectra, temporal waveforms, and average power at both exit ports. By analyzing temporal traces and output to reject port ratio power, we can distinguish between eight states of operation which follow an exact pattern. In the case of the single-pulse regime, we performed a further laser characterization, including relative intensity noise.

Numerical simulation of two-soliton and three-soliton molecules evolution in passively mode-locked fiber laser

“…Even when the same operation is performed in these conventional lasers at low pumping power, only single pulses are obtained. In contrast to previous cases to generate multi-pulses by increasing the pumping power [26], [44], the operating pumping powers of the multi-pulse states of our laser are lower than that of soliton states, and the number of pulses can remain constant as the pumping power decreases gradually in a certain range. Figure 4(b) shows the RF spectrum of the multi-pulse state at 370 mW.…”

“…However, the pulses in this regime generally lack long-term stability, and the spectral changes show a degree of randomness with variations in pumping power. Moreover, adjusting the pumping power and intracavity dispersion can change the number and time-domain distribution of multi-pulses [26], [27]. As the original multi-pulse configuration is disrupted, it makes it difficult to discover the underlying regularities.…”

Fiber-Interferometric Second Harmonic Generator with Dual-Color Standard Quantum-limited Noise Performance

“…$ ⁄ ) in combination with a 45° Faraday-rotator (FR, single-pass) before entering a parallel transmission grating pair (LightSmyth T-1000-1040 Series) with 1000 lines/mm grating constant in double pass configuration for tunable dispersion-management. The pulse train then enters a nonlinear and reflective fiber interferometer (NLI), which can be realized e.g., in configuration of a linear self-stabilized fiber interferometer (LSI) or a nonlinear amplifying loop mirror (NALM); both systems are currently often used by the research community as artificial saturable absorbers in ultra-low noise mode-locked fiber lasers [36][37][38].…”

Fiber-Interferometric Second Harmonic Generator with Dual-Color Standard Quantum-limited Noise Performance

“…It then propagates through a tunable phase-bias module, consisting of an eight-wave plate (EWP, rotation angle 𝜽 𝝀/𝟖 ) and HWP3 (rotation angle 𝜽 𝝀/𝟐 ) in combination with a 45° Faraday-rotator (FR, single-pass) before entering a parallel transmission grating pair (GP, LightSmyth T-1000-1040 Series) with 1000 lines/mm grating constant in double pass configuration for tunable dispersion-management. The pulse train then enters a nonlinear and reflective fiber interferometer (NLI), which can be realized e.g., in configuration of a linear self-stabilized fiber interferometer (LSI) or a nonlinear amplifying loop mirror (NALM); both systems are currently often used by the research community as artificial saturable absorbers in ultra-low noise mode-locked fiber lasers [36][37][38]. The NLI fulfills the same dual functionality in both configurations; amplification of the input signal and accumulation of a nonlinear phase-difference ∆𝝋 𝒏𝒍 between two orthogonal polarization modes that propagate independently in the respective NLI arms, resulting in an intensitydependent nonlinear polarization rotation (NPR).…”