Mode-locked ytterbium fiber laser tunable in the 980-1070-nm spectral range.

Spectral tuning of a mode-locked Yb-doped fiber laser over a 90-nm range is reported. Using semiconductor saturable absorber mirrors in a fiber laser cavity incorporating a grating-pair dispersive delay line, we obtain reliable self-starting mode locking over the whole tuning range. The wide tuning range is achieved by optimization of reflection characteristics and bandgap energy of the multiple-quantum-well semiconductor saturable absorber and by proper engineering of the laser cavity.

High-power, low-noise, Yb-doped, cladding-pumped, three-level fiber sources at 980 nm.

We present results on a high-power, cladding-pumped, Yb-doped fiber emitting at 977 nm in laser and ampllified-spontaneous-emission source configurations. We obtained up to 1.4 W of fiber-coupled, single-mode output power and slope efficiency as high as 68%. To our knowledge these are the highest powers efficiencies achieved from a single-mode fiber laser at approximately 980 nm and the first demonstrated results on a high-power amplified-spontaneous-emission source in this wavelength range. High power and high slope efficiency are achieved by using a high numerical aperture (> 0.7), a jacketed air-clad fiber, and a high-brightness pump source. Both types of sources exhibit relative intensity noise below -130 dB/Hz and are thus suitable for a wide range of applications.

Enhanced Q switching in double-clad fiber lasers.

A novel cladding pumped Nd(3+) fiber laser operating in an enhanced Q-switched regime with a stable repetition rate is described. By exploiting fiber nonlinearities in the laser cavity, we demonstrated a peak power of 3.7 kW enhanced by an order of magnitude greater than that of conventional Q-switched fiber devices. Pulse durations as short as 2 ns have been achieved.

Environmentally stable picosecond ytterbium fiber laser with a broad tuning range.

We demonstrate a widely tunable passively mode-locked fiber laser operating at a fundamental frequency of 80 MHz with an output power of 90 mW. The laser is capable of generating 5-ps pulses in the region 1010-1064 nm. A strong mode-locking mechanism promoted by frequency-shifted feedback allows us to operate in simultaneous Q-switched and mode-locked regimes and to obtain peak power in excess of 1.2 kW.

Soliton fiber laser with a hybrid saturable absorber.

We present an experimental study of a picosecond fiber soliton laser in which mode locking is achieved by the combined action of a multiple-quantum-well saturable absorber and a nonlinear amplifying loop mirror. In this configuration the multiple-quantum-well sample acts not only as a saturable absorber but also as a passive phase modulator, while the inclusion of a nonlinear amplifying loop mirror fixes the energy of the generated pulses. The laser stably operates at a repetition rate of 250 MHz with a timing jitter below 10 ps.

Femtosecond harmonically mode-locked fiber laser with time jitter below 1 ps.

We have made an experimental study of the time jitter in a harmonic passively mode-locked fiber soliton ring laser. We demonstrate that jitter as low as 600 fs (100-550 Hz), which is less than the soliton pulse width, can be achieved at a repetition frequency of 463 MHz. The results support the suggestion that the stability of the laser is dependent on the long-range soliton interaction through the excitation of acoustic waves that is induced by the propagating pulses.

Soliton interaction in the presence of a weak nonsoliton component.

We study both experimentally and theoretically soliton interaction in the presence of a weak nonsoliton component and show that the existence of a frequency-shifted cw wave results in a temporal shift of the soliton.

Increased amplifier spacing in a soliton system with quantum-well saturable absorbers and spectral filtering.

The spacing between optical amplifiers in a long-haul soliton system may be increased to 100 km by using only passive quantum-well saturable absorbers and narrow-band filters for soliton control. After transmission over 9000 km at 10 Gbits/s, the effects of soliton-soliton interaction and Gordon-Haus jitter in the proposed systemyield bit error rates of better than 10(-9).

Amplification of femtosecond pulses in a passive, all-fiber soliton source.

We report a theoretical and experimental study of the amplification of femtosecond soliton pulses generated by a passively mode-locked fiber laser in a high-gain erbium-doped fiber amplifier (EDFA). Results on the spectral and temporal evolution of 450-fs soliton pulses propagating within an EDFA are presented. Power gains as high as 30 dB and the generation of sub-100-fs Raman colored solitons are observed. The results are found to be well described by the theoretical model presented.