Ultrabroadband, few-cycle pulses directly from a Mamyshev fiber oscillator

Abstract

While the performance of mode-locked fiber lasers has been improved significantly, the limited gain bandwidth restricts them to generate ultrashort pulses approaching a few cycles or even shorter. Here we present a novel method to achieve few cycle pulses (~5 cycles) with ultra-broad spectrum (~400 nm). To our best knowledge, this is the shortest pulse width and broadest spectrum directly generated from fiber lasers. It is noteworthy that a dramatic ultrashort pulse evolution can be stabilized in a laser oscillator by the unique nonlinear processes of a self-similar evolution as a nonlinear attractor in the gain fiber and a perfect saturable absorber action of the Mamyshev oscillator.

Output Pulse Characteristics of a Mamyshev Fiber Oscillator

“…In arm 2, a 600 lines/mm grating, together with two collimators, serves as a tunable filter. To start the Mamyshev oscillator, two quarter-wave plates (QWP 1, QWP 2), one half-wave plate (HWP), and a polarization beam splitter (PBS) are added in arm 2, serving as a nonlinear polarization rotation-based artificial saturable absorber [17,22]. Before the grating, the HWP 2 is used to optimize the diffraction grating efficiency.…”

“…Photonics 2021, 8, x FOR PEER REVIEW 8 of 13 polarization rotation-based artificial saturable absorber [17,22]. Before the grating, the HWP 2 is used to optimize the diffraction grating efficiency.…”

“…In 2015, an improved version of an environmentally stable Yb-doped fiber Mamyshev oscillator was reported, which generated laser pulses with energy of 2.8 nJ [11]. Subsequently, the characteristics of an Mamyshev oscillator have been widely studied, and the performance of the output pulses has been gradually improved [14][15][16][17][18][19][20][21]. By inserting a highly nonlinear crystal fiber into the cavity, few-cycle pulses with ~400 nm ultra-broad spectrum are obtained from a Mamyshev oscillator [17].…”

“…Subsequently, the characteristics of an Mamyshev oscillator have been widely studied, and the performance of the output pulses has been gradually improved [14][15][16][17][18][19][20][21]. By inserting a highly nonlinear crystal fiber into the cavity, few-cycle pulses with ~400 nm ultra-broad spectrum are obtained from a Mamyshev oscillator [17]. T. Wang et al investigated the possibility of obtaining high-energy pulses in an all-fiber Mamyshev oscillator, and a single-pulse energy of 83.5 nJ was achieved [18].…”

A 200 MHz Compact Environmentally-Stable Mode-Locked Figure-9 Fiber Laser

“…The developing trend has put a critical requirement on compactness, cost efficiency and stable performance of lasers. By contrast, fiber lasers have inherent novel features including simpler structure, less space usage, and lighter weight [8,9]. Therefore, it is a promising pulse source for operations outside the laboratory.…”