Investigation of ellipticity and pump power in a passively mode-locked fiber laser using the nonlinear polarization rotation technique

Abstract

An elliptical initial polarization state is essential for generating mode-locked pulses using the nonlinear polarization rotation technique. In this work, the relationship between the ellipticity ranges capable of maintaining mode-locked operation against different pump power levels is investigated. An increasing pump power, in conjunction with minor adjustments to the polarization controller's quarter waveplate, results in a wider ellipticity range that can accommodate mode-locked operation. Other parameters such as noise, pulsewidth, and average output power are also observed to vary as the ellipticity changes.OCIS Over the last few years, fiber lasers have become the key focus in the development of new laser applications due to their significant advantages over their solid state counterparts. The key advantages of fiber lasers include their low weight and compact size, as well as relatively lower losses and ease of alignment. These characteristics make fiber lasers a crucial component of today's optical communication, carrying terabits of information across continents. While fiber lasers can be configured to suit multiple applications, pulsed fiber lasers in particular have recently garnered substantial attention in generating high energy pulses. These pulses serve a variety of applications, including communications, sensing, manufacturing, and medicine. Pulsing in fiber lasers can be achieved by multiple active and passive means, with the most common being Q-switching and mode-locking. Of the two, mode-locking is preferred for applications requiring high frequency pulses but at a lower power.Fiber lasers can be mode locked in three ways; either actively, passively, or as a hybrid of both. Active modulation is reliable and offers tunability of various parameters, but generates a broad pulsewidth [1] , and also requires bulky and expensive components. Passive modulation, on the other hand, modulates the loss and gain of the laser using saturable absorbers (SAs) [2][3][4][5] or by inducing SA action, such as nonlinear amplifying loop mirrors (NALMs) [6] and nonlinear polarization rotation (NPR) [7,8]

In-band pumped Q-switched fiber laser based on monolayer graphene

“…The slope efficiency of this laser is about 17.03%, with maximum output of 34.25 mW. Compared with most of its conventionally LD-pumped counterparts [3,[36][37][38], this in-band pumped Q-switched laser outperforms in terms of slope efficiency and output power. Nevertheless, we test the PI-ISO (designed operating at 1064 nm) and 20% output coupler, and find that the insert loss at 1080 nm are ~30% and ~5%, respectively, which means there is about 35% insertion loss in a single round, lowering the conversion efficiency.…”

High-power passively Q-switched Yb-doped fiber laser based on Tin selenide as a saturable absorber

“…However, the zero-bandgap structure limits its advanced application as optoelectronic devices. Subsequently, inspired by graphene, 2D materials including topological insulators (TIs) [13][14][15][16][17], transition metal dichalcogenides (TMDs) [18][19][20][21][22][23][24][25][26] and black phosphorus [27][28][29][30] have been extensively employed as SAs for demonstrating pulsed laser operations. In particular, TMDs including MoS 2 [18,19,22], MoSe 2 [20][21][22] and WS 2 [22][23][24][25][26] have attracted more attention in the field of ultra-fast optics due to their obvious advantages of a wide absorption range, easy preparation, low cost, fast recovery time, high damage threshold, high third-order nonlinear coefficients, low saturation threshold and suitable bandgap value.…”