Switchable Ytterbium Fiber Laser Based on a Symmetrical Long-Period Fiber Grating

Abstract

In this study, a switchable ytterbium-doped fiber laser based on symmetrical long-period fiber grating (LPFG) is presented. The LPFG is used as a wavelength-selective filter (WSF). Utilizing this WSF, the laser can emit one, two, or multiple stable output beams by adjusting the temperature on the LPFG from 20 °C to 600 °C. In addition, switching is also possible by adjusting the curvature of the LPFG from 0.399 to 0.709 m -1 . The symmetrical LPFG was fabricated by combining the cladding shaping with the thermal core expansion techniques by using a CO2-laser LZM-100 glass-processing system. The experimental results show a side-mode suppression ratio (SMSR) of 49 dB and a linewidth of 0.06 nm, within the range from 1038 to 1080 nm. In conclusion, the main achievement of this switchable laser is the high SMSR and stable output for high values of temperature, using a repeatable, simple, easy construction, and cost-effective laser tuning technique.

Electrically tunable mode-locked fiber laser using laser induced graphene assisted long-period fiber grating

“…The variation of transmission spectrum produced by adjusting the temperature of LPFG, which is essentially the result of the index modulation. When the refractive index profile of LPFG changes, it breaks the cladding-mode symmetry and promotes the coupling of the fundamental mode to higher modes [25]. Thus, the laser net gain in the cavity is reshaped.…”

“…The other solutions to achieve the modifications of the LPFG were also reported, for example, Jun et al experimentally controlled the spectral shape by adjusting the temperature of the LPFG section with divided coil heaters [24]. In 2021, Silva-Alvarado et al adjusted the temperature on the LPFG to achieve a stable switchable multi-wavelength ytterbiumdoped fiber laser [25]. Considering the inherent merits of LPFG, it is interesting to develop LPFG-based mode-locked fiber lasers with simple structure, good stability and high cost performance.…”