## 5 Discussion  
The observed ability to tune the laser, produce switchable dual wavelengths, and sequentially switch between multiple wavelengths is due to the combined effects of the MZFI's spectral shaping, the EDF gain dynamics, and intracavity polarization control. The MZFI generates a comb-like spectrum through periodic phase shifts and interference resulting from the designed geometry and changes in the effective refractive index of the coupled light modes due to the elasto-optic effect produced by inducing curvature. As curvature increases, these modifications make a series of spectral peaks corresponding to resonance conditions for specific wavelengths. Figures 4 and 5 illustrate that increased curvature enhances the prominence of the comb-like spectrum, improves fringe visibility, and causes observable wavelength shifts, indicating the system's sensitivity to curvature  
Figure 14: (**a**) Power stability of the quintuple-wavelength laser system, (**b**) maximum wavelength shift of 0.07 nm, and (**c**) maximum amplitude fluctuation of 1.7 dB for the 1561.58 nm line. Figure 15: (**a**) Power stability of the sextuple-wavelength laser system, (**b**) negligible wavelength shift, and (**c**) maximum amplitude fluctuation of 2.71 dB for the 1562.98 nm line. changes. Minor variations in visibility or wavelength shifts can redistribute the EDF gain profile, preferentially enhancing laser oscillation and stabilization at the comb peaks. At relatively low curvatures (Figure 6), while fringe visibility is still insufficient for multi-wavelength oscillation, spectral shifts still occur, resulting in a single wavelength tuning by 5.65 nm with an optical OSNR above 50 dB. At higher curvature levels, there is a notable increase in fringe visibility, with the switchable dual-wavelength emission feature becoming evident in the 1543.21 nm and 1563.66 nm range (Figure 7) with an OSNR exceeding 40 dB. The increased curvature refines the spectral comb pattern and adjusts the gain profile, supporting the dual-wavelength operation and improving laser performance. The switchable multi-wavelength performance is caused when the curvature is adjusted at 2.363 m\({}^{-1}\), producing a comb-like output showing a flattened profile. This effect is clearly comparable with the profile at 2.31 m\({}^{-1}\) from Figure 4b (pink line), where the comb-like spectrum is reduced (visibility of 0.35), leading to consistent gain across the spectral lasing peak (see Figure 8a). The reduction in visibility likely indicates a more uniform distribution of the optical power across the spectrum. This condition promotes strong mode competition within the laser cavity, causing side modes to oscillate as the gain flattening equalizes the lasing conditions for multiple wavelengths. Simultaneously, by fine-tuning the polarization state, the side modes experience more favorable conditions for amplification by receiving sufficient gain to exceed the lasing threshold, resulting in the excitation of additional lasing wavelengths to be selected sequentially. The demonstrated stability of this configuration highlights its suitability for advanced multi-wavelength laser systems, meeting rigorous performance benchmarks. Stability is essential for reliable operation, validating system performance, and ensuring consistent output in practical applications. Several external factors can significantly influence stability variations. Small mechanical vibrations arising from the manipulation of setup components can disrupt stability. Temperature fluctuations in the surrounding medium of the tapered region can induce thermal expansion, altering the path length of the MZFI, and the effect of humidity can affect their refractive index and transmission properties. Furthermore, fluctuations in pump power can contribute to these instabilities, affecting the system's overall performance. The approach's robustness and adaptability confirm its effectiveness, making it a superior choice for high-performance laser systems and paving the way for future advancements.