Generation of 70-fs pulses at 2.86 {\mu}m from a mid-infrared fiber laser

TL;DR

This paper demonstrates a compact, robust method to generate 70-fs pulses at 2.86 μm from a mid-infrared fiber laser using nonlinear spectral broadening and compression, achieving the shortest pulses from such a system to date.

Contribution

The work introduces a simple, scalable approach for generating few-cycle mid-infrared pulses using fiber nonlinearities and compression, with experimental validation and numerical modeling.

Findings

Achieved 70 fs pulses at 2.86 μm from a fiber laser system.

Spectral broadening to 141 nm via self-phase modulation in As2S3 fiber.

System is compact, robust, and uses commercially available components.

Abstract

We propose and demonstrate a simple route to few-optical-cycle pulse generation from a mid-infrared fiber laser through nonlinear compression of pulses from a holmium-doped fiber oscillator using a short length of chalcogenide fiber and a grating pair. Pulses from the oscillator with 265-fs duration at 2.86 {\mu}m are spectrally broadened through self-phase modulation in step-index As2S3 fiber to 141-nm bandwidth and then re-compressed to 70 fs (7.3 optical cycles). These are the shortest pulses from a mid-infrared fiber system to date, and we note that our system is compact, robust, and uses only commercially available components. The scalability of this approach is also discussed, supported by numerical modeling.