Low Noise, Mode-Locked 253 MHz Tm/Ho Fiber Laser With Core Pumping at 790 nm

We demonstrate a single-mode Tm/Ho co-doped mode-locked fiber laser with a repetition rate of 253 MHz that is directly core pumped at a wavelength of 790 nm. In a soliton mode-locked linear fiber laser cavity, femtosecond pulses with transform-limited pulse durations of 315 fs are generated. With single-mode core pumping, the high peak absorption of the gain medium is utilized to obtain an optical spectrum with suppressed ripples and high signal-to-background levels in the RF spectrum above 70 dB. Good noise performance with a rms relative intensity noise of 0.11% [10 Hz, 2 MHz] and a timing jitter of 20 fs [100 Hz, 2 MHz] is demonstrated. For a single pulsing mode-locking regime, a reproducible and stable peak wavelength tunability of the optical spectrum is achieved over 11 nm by pump power tuning.