Figure 2
From: Super-flat supercontinuum generation from a Tm-doped fiber amplifier

Supercontinuum generation from the Tm-doped fiber amplifier at 20 kHz repetition rate with no 793 nm pump power: (a) direct-output configuration with no passive fiber at the output end of the Tm-doped fiber; (b) pigtail configuration with 1 m long passive fiber at the output end of the Tm-doped fiber.