Modeling and analysis of polarization effects in Fourier domain mode-locked lasers

Abstract

We develop a theoretical model for Fourier domain mode-locked (FDML) lasers in a non-polarization-maintaining configuration, which is the most widely used type of FDML source. This theoretical approach is applied to analyze a widely wavelength-swept FDML setup, as used for picosecond pulse generation by temporal compression of the sweeps. We demonstrate that good agreement between simulation and experiment can only be obtained by including polarization effects due to fiber bending birefringence, polarization mode dispersion, and cross-phase modulation into the theoretical model. Notably, the polarization dynamics are shown to have a beneficial effect on the instantaneous linewidth, resulting in improved coherence and thus compressibility of the wavelength-swept FDML output.

Efficient simulation of the swept-waveform polarization dynamics in fiber spools and Fourier domain mode-locked (FDML) lasers

“…The matrices M FRM , M L,n and M NL,n defined in Eqs. (11), (17) and (20), as well as the matrix representing the polarization controller M PC given by Eq. (13), are all of the form Eq.…”

“…If no polarization maintaining (PM) optical components such as special PM fiber are used, polarization effects greatly influence the FDML operating characteristics due to effects such as cross-phase modulation, bending birefringence and polarization-mode dispersion (PMD) in the fiber spool [16,17]. Theoretical models for FDML lasers typically do not take into account the polarization degree of freedom of the optical field [2,[18][19][20][21], and are thus only suitable for PM FDML setups.…”

Hyperspectral stimulated Raman microscopy with two fiber laser sources

“…Besides OCT, also non-destructive sensing and testing, optical molecular and functional imaging as well as short pulse generation have been shown with this laser [30][31][32][33][34][35][36][37]. In this work, the inherent low noise and good sweep-to-sweep correlation [38][39][40][41][42][43][44][45][46][47] are exploited to provide -in combination with a dual-balanced detection scheme -a fundamentally shot-noise limited detection sensitivity for SRS measurements. The FDML laser periodically and continuously tunes its wavelength over more than 150 nm around 1300 nm or 1550 nm with a repetition rate of 415 kHz at an average output power of up to 120 mW [48][49][50].…”

High-resolution retinal swept source optical coherence tomography with an ultra-wideband Fourier-domain mode-locked laser at MHz A-scan rates

“…We use a swept source OCT system, based on a Fourier Domain Mode Locked (FDML) laser. Due to their stationary mode of operation [32], FDML lasers have the unique advantage that they can combine very narrow, picometer scale linewidth [33,34], meter range coherence [35,36], stable polarization [37][38][39][40] and very high sweep rates [41]. The dynamic Doppler shift of the light wave inside the FDML cavity by the moving mirror of the intra-cavity Fabry Perot filter enables modehop-free tuning [42] and ultra-low intensity noise [36].…”