# Tunable Wavelength-Multiplexed Dual-Frequency Bound Pulse in a Carbon-Nanotube-Based Fiber Laser

## TL;DR

This paper presents a fiber laser that generates tunable dual-frequency pulses at different wavelengths using carbon nanotubes and polarization control.

## Contribution

A new method for generating tunable wavelength-multiplexed dual-frequency pulses in a carbon-nanotube-based fiber laser is introduced.

## Key findings

- Three coexisting wavelength-multiplexed dual-frequency pulses are demonstrated experimentally and theoretically.
- Polarization control allows switching between asynchronous and bound soliton states.
- A simulation using coupled Ginzburg–Landau equations explains the pulse dynamics.

## Abstract

We experimentally and theoretically demonstrate coexistence of three different wavelength-multiplexed bound dual-frequency pulses in an all-fiber mode-locked fiber laser, effectively achieved by exploiting polarization-dependent loss effects and two uneven gain peaks of Er-doped fiber. With the single wall carbon-nanotube-based intensity modulation, wavelength-multiplexed dual-frequency pulses located at 1531.1 nm and 1556.6 nm are obtained. Changing the polarization rotation angles in the fiber cavity, one of the two asynchronous pulses evolves into a bound state of a doublet, in which the center wavelength of the bound solitons is centered at ~1530 nm or ~1556 nm. The relative phase between the two bound solitons or modulation depth of bound solitons can be switched by a polarization controller. A simulation method based on coupled Ginzburg–Landau equations is provided to characterize the laser physics and understand the mechanism behind the dynamics of tuning between different bound dual-frequency pulses. The proposed fiber laser will provide a potential way to understand multiple soliton dynamics and implementation in optical frequency combs generation.