Observation of quantum-limited timing jitter in an active, harmonically mode-locked fiber laser

O-Band Frequency-Tunable (10–22 GHz) Ultra-Low Timing-Jitter (<12-fs) Regenerative Mode-Locked Laser

A frequency-tunable and low-timing-jitter O-band regenerative mode-locked laser (RMLL) using an optoelectronic oscillation configuration and electric-controlled yttrium iron garnet (YIG) bandpass filter is proposed and demonstrated. In this scheme, an O-band semiconductor optical amplifier (SOA) is used as the gain medium of the RMLL to realize a dispersion-management-free operation during frequency tuning. With a polarization-maintaining fiber loop of 300 m, we produced a robust frequency-tunable RMLL with a pulse width below 16 ps, phase noises below −123 dBc/Hz at a 10-kHz frequency offset from the carrier frequency, and timing jitter less than 12 fs (integrated in 1-kHz to 1-MHz range) in a frequency tuning range between 10 GHz and 22 GHz.

Linear dissipative soliton in an anomalous-dispersion fiber laser

We report on the generation of linear dissipative soliton (LDS) from an erbium-doped actively mode-locked fiber laser. We show that depending on the down-chirping effect of quadratic phase modulation, instead of the fiber nonlinear Kerr effect in an all-normal-dispersion (ANDi) cavity, stable LDS can be realized in the linear dissipative system. The DS operation of ANDi laser and LDS operation of anomalous dispersion laser are experimentally investigated and compared, and the formation mechanisms of the DS and LDS are discussed. Finally, optical frequency comb generated by the LDS laser is demonstrated.

High-repetition-rate, stretch-lens-based actively-mode-locked femtosecond fiber laser

We propose and demonstrate a novel actively mode-locked fiber laser based on a stretch-type time-lens. The pulse generated by this scheme has high repetition rate and large bandwidth while no nonlinearity is participated. A 10-GHz chirped pulse train with 18-ps duration and 11.6-nm bandwidth is obtained, which is then extra-cavity compressed down to 825 fs. The pulse characteristics dependent on the cavity dispersion and time-lens strength are discussed. Pulse propagation in the laser is similar with dissipative soliton in all-normal-dispersion laser. The results demonstrate that the stretch-lens inside the actively mode-locked laser can effectively broaden the spectral bandwidth, instead of the fiber nonlinearity, which can then support a high-repetition-rate "linear dissipative soliton" pulse shaping in a very compact design.

Complete characterization of quantum-limited timing jitter in passively mode-locked fiber lasers

We characterize the timing jitter of passively mode-locked, femtosecond, erbium fiber lasers with unprecedented resolution, enabling the observation of quantum-origin timing jitter up to the Nyquist frequency. For a pair of nearly identical 79.4MHz dispersion-managed lasers with an output pulse energy of 450pJ, the high-frequency jitter was found to be 2.6fs [10kHz, 39.7MHz]. The results agree well with theoretical noise models over more than three decades, extending to the Nyquist frequency. It is also found that unexpected noise may occur if care is not taken in optimizing the mode-locked state.

Timing jitter and phase noiseof mode-locked fiber lasers

The noise properties of mode-locked fiber lasers differ in various respects from those of bulk lasers. The reasons for this are both quantitative and qualitative differences concerning the pulse formation. The underlying theoretical aspects are discussed in detail. It is found that the achievable noise level and the limiting effects depend strongly on the type of fiber laser. Depending on the pulse formation mechanism, noise levels may be much higher than predicted by simplified models.

Direct generation of a 10 GHz 816 fs pulse train from an erbium-fiber soliton laser with asynchronous phase modulation

By employing the technique of asynchronous mode locking, we have successfully demonstrated direct generation of stable 10 GHz 816 fs pulse trains with a supermode-suppression ratio >70 dB from a hybrid mode-locked Er-fiber laser. When the modulation frequency deviates from the cavity harmonic frequency by 15-40 kHz, stable femtosecond soliton pulses are formed. Our results demonstrate that asynchronous mode locking can act as an effective mechanism for achieving a shorter pulse width and for stabilizing high-repetition-rate pulse trains in soliton fiber lasers.

Nearly quantum-noise-limited timing jitter from miniature Er:Yb:glass lasers

We report on nearly quantum-limited timing-jitter performance of two passively mode-locked Er:Yb:glass lasers with a repetition rate of 10 GHz. The relative timing jitter of both lasers was measured to be 190 fs (100 Hz-1.56 MHz) root mean square. The remaining cavity-length fluctuations are below 7.5 pm in the 6 Hz-8 kHz frequency range, indicating the stability of a rugged miniature cavity setup. By actively controlling the cavity length we reduced the timing jitter to 26 fs (6 Hz-1.56 MHz). We also discuss the influence of cavity length on the practically achievable timing jitter.

Ultralow-noise mode-locked laser with coupled optoelectronic oscillator configuration

We describe simultaneous generation of ultralow-noise optical pulses and microwave signal with a mode-locked fiber laser in a coupled optoelectronic oscillator configuration. We demonstrate 9.2-GHz optical and microwave signals with the measured phase noise of -140 dBc/Hz at 10-kHz offset frequency. We show that the mode-locked laser in the photonic oscillator serves as a high-Q filter and is responsible for the observed low phase noise.