RESUMEN
A few-mode erbium-doped waveguide amplifier (FM-EDWA) with a confined Er3+ doped ring structure is proposed to equalize the differential modal gain (DMG). The FM-EDWA amplifying three spatial modes (LP01, LP11a and LP11b) is optimized by genetic algorithm and fabricated using precise lithography overlay alignment technology. We observe gain values of over 14â dB for all modes with DMG of 0.73â dB at 1529â nm pumped only with LP01 for the power of 200â mW. Furthermore, a flat gain of more than 10â dB is demonstrated across 1525-1565â nm, with a sufficiently low DMG of less than 1.3â dB.
RESUMEN
A novel, to the best of our knowledge, few-mode waveguide amplifier with a dual-layer coronal core is first proposed. Reconfiguring the refractive index profile is adopted to equalize the modal gains pumped in a single mode. The polymer in terms of the prominent advantages of simple processing and the ease of adjusting refractive index is utilized. The waveguide supporting LP01, LP11a, and LP11b is optimized by the genetic algorithm and fabricated by accurate alignment mask. The crosstalk effect and modal profiles are characterized. The modal gains with different signal power and pumping modes are revealed. The schemes in forward and backward pumps are represented. An average gain of 11.84â dB per mode and an ultralow differential modal gain of 0.36â dB are obtained in a 0.3â cm waveguide at 1526â nm through backward pumping of the LP21b mode at 240â mW for an input signal power of 0.1â mW.