Development of Dual-Comb Ultrafast Erbium Fiber Lasers Using Homemade Graphene-Based Saturable Absorbers

Education Level

Undergraduate

Faculty Advisor(s)

Professor Ahmet Akosman

Academic Department(s)

Engineering

Comments

This research was presented at the 2024 Rhode Island Summer Undergraduate Research Symposium, held on Friday, July 26, at the University of Rhode Island and supported by RI NSF EPSCoR.

Symposium Date

2024

Abstract

In this study, an ultrafast erbium laser was built using homemade 2-dimensional saturable absorbers. There are several components utilized in the laser’s setup, beginning with a 980nm pump, providing the system with up to 700mW of optical power and protected using an isolator. This source then connects to the main laser cavity, which consists of a fiber WDM (wavelength division multiplexer), 0.90cm of Liekki erbium gain fiber, 1m of PMF (polarization maintaining fiber), approximately 11m of SMF (single mode passive fiber), a graphene saturable absorber, a 1550nm fiber isolator to control the flow of light within the system, and a 10% fiber output coupler to control the amount of energy released from the cavity. In order to minimize loss in the cavity, the vast majority of laser components were spliced together wherever possible. Fibers were connectorized at the input and output of the cavity, PMF, and the ferrule connection where the saturable absorber is deposited. The laser cavity was analyzed through the use of several devices, such as an optical power meter, oscilloscope, and optical spectrum analyzer. These devices allowed for measuring power output from the laser cavity for a range of source currents and identifying the resulting pulses from mode-locked signals.

The saturable absorbers used within this laser cavity were hand-made in the lab using the method known as liquid phase exfoliation. The 2d saturable absorber materials developed for the laser cavity include graphene, molybdenum disulfide, and a molybdenum disulfide/graphene mixture. Solutions containing a combination of the powdered materials and an IPA/water mixture were prepared, then placed in an ultrasonic processor, and lastly placed into a centrifuge resulting in the 2d saturable absorbers suspended in liquid solutions. The quality of these solutions was then tested to determine the concentration and thickness of the 2d materials. This study shows promise in finding an easy, efficient method for preparing high-quality 2d saturable absorbers for achieving mode-locking in laser systems.

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