Black Phosphorus-Polymer Composites for Pulsed Lasers

TL;DR

This paper explores black phosphorus-polymer composites as saturable absorbers for fiber lasers, demonstrating stable Q-switched pulses with high energy, and highlights their potential for various photonic applications.

Contribution

It introduces a novel BP-polymer composite fabrication method that enhances stability and demonstrates its effectiveness in high-energy pulsed laser generation.

Findings

BP-polymer composite exhibits 10.6% modulation depth

Achieved stable Q-switched pulses with ~194 nJ energy

Composite films are easy to handle and versatile for applications

Abstract

Black phosphorus is a very promising material for telecommunication due to its direct bandgap and strong resonant absorption in near-infrared wavelength range. However, ultrafast nonlinear photonic applications relying on the ultrafast photo-carrier dynamics as well as optical nonlinearity in black phosphorus remain unexplored. In this work, we investigate nonlinear optical properties of solution exfoliated BP and demonstrate the usage of BP as a new saturable absorber for high energy pulse generation in fiber laser. In order to avoid the oxidization and degradation of BP, we encapsulated BP by polymer matrix which is optically transparent in the spectrum range of interest to form a composite. Two fabrication approaches were demonstrated to produce BP-polymer composite films which were further incorporated into fiber laser cavity as nonlinear media. BP shows very fast carrier dynamics and BP-polymer composite has a modulation depth of 10.6%. A highly stable Q-switched pulse generation was achieved and the single pulse energy of ~194 nJ was demonstrated. The ease of handling of such black phosphorus-polymer composite thin films affords new opportunities for wider applications such as optical sensing, signal processing and light modulation.