Fig. 1. Schematic configuration of the peak power tunable DSR laser and Raman converter. YDF: Yb-doped double-clad fiber; LD: laser diode; PC: polarization controller; BPF: bandpass filter; OC: output coupler; CIR: circulator.

Fig. 2. Properties of the DSR laser. (a) RF spectrum and the pulse train (inset) at a 5.650 MHz repetition rate. (b) Pulse waveform and spectra (inset) variations with the power of LD1. (c) Pulse waveform variation and (d) RF spectrum evolution with increasing power of LD2. Pulse peak power and width variation with (e) LD1 power and (f) LD2 power.

Fig. 3. Spectra and temporal profiles of the Raman converted output pulses after propagating through 1-km-long HI1060 fiber pumped with DSR pulses at 5.65 MHz. Output spectra on (a) logarithmic and (c) linear scales. (b) Input DSR pulses. (d) Output pulses from the end of HI1060 fiber.

Fig. 4. Output pulse characteristics after bandpass filtering. Temporal profiles and spectra of the (a), (e) passing and (b), (f) reflecting pulses from BPF1. Temporal profiles and spectra of the (c) passing and (d) reflecting pulses from BPF2. (a)–(d) are collected for pulses exciting the first-order Raman line while (e) and (f) are for pulses exciting the second-order Raman line.

Fig. 5. Spectra and temporal profiles of the Raman-converted output pulses after propagating through 1-km-long HI1060 fiber pumped with DSR pulses at 6.3 MHz. Output spectra on (a) logarithmic and (b) linear scales. (c) Input DSR pulses at 6.3 MHz. (d) Output pulses from the end of the HI1060 fiber. (e) Temporal profiles and spectra of output pulses after filtering of BPF1.