Abstract
We demonstrate a long-term stable, all-fiber, erbium-doped femtosecond laser mode-locked by a black phosphorus saturable absorber. The saturable absorber, fabricated by scalable and highly controllable inkjet printing technology, exhibits strong nonlinear optical response and is stable for long-term operation against intense irradiation, overcoming a key drawback of this material. The oscillator delivers self-starting, 102 fs stable pulses centered at 1555 nm with 40 nm spectral bandwidth. This represents the shortest pulse duration achieved from black phosphorus in a fiber laser to date. Our results demonstrate the great potential for black phosphorus as an excellent candidate for long-term stable ultrashort pulse generation.
Highlights
Mode-locked fiber laser sources are established as a common tool for femtosecond pulse generation at MHz repetition rates
In soliton fiber lasers, the practically achievable pulse duration is typically limited to ~200 fs as the pulse duration (τ) of fundamental solitons has to satisfy τ > β2 L, where β2 is the group velocity dispersion (GVD), and L is the cavity length [1]
In addition to the fiber amplifier, the cavity consists of a 20: 80 fiber-pigtailed optical output coupler (OC) for both spectral and temporal diagnostics, a polarization-independent inline fiber isolator to ensure unidirectional propagation and a polarization controller, all of which is made of single-mode fiber (SMF) with a GVD of −22 ps2/km
Summary
Mode-locked fiber laser sources are established as a common tool for femtosecond pulse generation at MHz repetition rates. While a large number of studies have reported stretched pulse fiber lasers using saturable absorbers (SAs) [2,3,4,5], two-dimensional (2D) nanomaterials (e.g. graphene [6,7], semiconducting transition metal dichalcogenides (s-TMDs) [8] and black phosphorus (BP) [9,10]) are often preferred as they offer strong intensity-dependent absorption, broadband working wavelength range, ultrafast carrier dynamics, in addition to the ease of all-fiber integration. Scalable fabrication of BP SAs with long-term operation stability in the ambient remains a key target for the successful use of this novel material In this manuscript, we report an ultrafast stretched pulse fiber laser integrating inkjetprinted BP-based SA fabricated from functional ink of liquid-phase-exfoliated BP. Our work highlights the applicability of BP-based devices for photonic applications requiring stable femtosecond pulse generation under ambient conditions
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