1.61–1.85 $\mu$m Tunable All-Fiber Raman Soliton Source Using a Phosphor-Doped Fiber Pumped by 1.56 $\mu$m Dissipative Solitons

Abstract

We demonstrate soliton self-frequency shift (SSFS) of more than 15.5 $\%$ of the optical frequency in a phosphor-doped silica fiber for the first time. This fiber shows great potential for supporting Raman-shift solitons above 1.8 $\mu$ m with a 1.56 $\mu$ m pumping, which is superior to the SSFS previously reported in conventional single-mode silica fiber. In our experiment, when the amplified dissipative-soliton pulses at 1.56 $\mu$ m are injected into a 960 m phosphor-doped silica fiber, SSFS is efficiently initiated, and the output spectrum of Raman solitons can be continuously tuned from 1.61 to 1.85 $\mu$ m. The Raman solitons have the shortest pulse duration of $\sim$ 800 fs and the pulse energy of $\sim$ 1 nJ. This 1.61–1.85 $\mu$ m ultrashort laser source can not only fill in the spectral gap between Er $^{3+}$ and Tm $^{3+}$ emissions but has potential applications in multiphoton microscopy and optical tomography as well.