Irl N. Duling

All-fiber ring soliton laser mode locked with a nonlinear mirror

An amplifying nonlinear-optical fiber loop mirror is used as the gain element in an all-fiber ring laser. The resulting double-loop structure resembles a figure eight. The output of the amplifying nonlinear-optical fiber loop mirror is fed back to the input through an optical isolator to ensure unidirectional operation. The laser produces 2-ps transform-limited pulses. The pulse energy corresponds to that of the fundamental soliton in the fiber used.

10-GHz, 1.3-ps erbium fiber laser employing soliton pulse shortening

An actively mode-locked single-polarization erbium fiber laser modulated at 10 GHz utilizes intracavity soliton formation to produce 1.3-ps pulses, well below the Kuizenga-Siegman limit, without passive mode locking. The observed degree of pulse shortening agrees with the predictions of recently developed soliton laser models. The pulse dropout ratio was measured to be less than 10(-12), and the rms amplitude and phase jitter are less than 1.1% and 0.16 ps, respectively.

Experimental study of sideband generation in femtosecond fiber lasers

We present a thorough experimental investigation of the phenomenon of soliton resonance sideband generation in femtosecond fiber lasers. The dependence of the sideband wavelengths on the dispersion and pulse length is confirmed. Third order dispersion is found to play a significant role in determining the sideband spectrum. We show that the minimum pulse length obtained in a fiber laser is determined by the cavity dispersion and relate this to loss into the sidebands. We show how the sideband spectrum can be used as a diagnostic of the fiber parameters and of the formation of ultrashort pulses in the laser. >

Dispersion in rare-earth-doped fibers.

Rare-earth dopants in optical fibers have in general been ignored as a source of dispersion. The host material dispersion has been assumed to be an adequate description of the dispersion properties. Resonant dispersion features owing to absorption by the rare-earth ions were observed that were comparable in magnitude with the host material dispersion. These observations have consequences in the design of fiber lasers, nonlinear fiber transmission systems, and analog information systems.

Synchronous amplification of subpicosecond pulses

In high-gain dye amplifiers, the effective storage time of the gain medium is only a few hundred picoseconds. Therefore, efficient amplification of ultrashort pulses places a stringent requirement on the synchronization between the pump pulse and the pulse to be amplified. We present a technique of short pulse generation using a dye laser synchronously pumped by a frequency-doubled CW mode locked Nd:YAG laser. Pulses as short as 70 fs are produced. The short optical pulses are subsequently amplified with two different synchronous amplification schemes using 100 ps pulses to establish the gain in the dye amplifier stages. Subpicosecond pulses with energies from a few hundred nanojoules at 500 Hz to a few hundred microjoules at 7 Hz can be obtained.

Dispersion management in a harmonically mode-locked fiber soliton laser

Harmonically mode-locked Er-fiber soliton lasers have become a reliable source of high-repetition-rate picosecond pulses in high-speed communications and photonic analog-to-digital conversion systems because of their low-noise, dropout-free operation. We have fabricated such a laser with a strongly dispersion-managed cavity and modeled its operation, and we have found that dispersion management significantly extends the power range over which uninterrupted single-pulse production is attained and dramatically decreases the effects of amplified spontaneous emission on the phase noise of the laser.

BROADBAND SQUARE-PULSE OPERATION OF A PASSIVELY MODE-LOCKED FIBER LASER FOR FIBER BRAGG GRATING INTERROGATION

A long-cavity, passively mode-locked erbium fiber laser operated in the square-pulse regime is demonstrated as a useful light source for interrogating fiber Bragg grating arrays. Output pulses with 4-W peak-power, 10-ns pulse widths, and bandwidths greater than 60nm were used successfully to interrogate 2% fiber Bragg gratings.

Operation of a nonlinear loop mirror in a laser cavity

A nonlinear loop mirror can be used as a solid state saturable loss element. The transmission characteristics of the different embodiments of this mirror are shown to change significantly when it is used in the soliton-forming wavelength range. The implications for its use in a laser cavity are discussed. >

Theoretical and experimental study of harmonically modelocked fiber lasers for optical communication systems

We study theoretically and experimentally actively modelocked fiber lasers that are used in high repetition rate optical communication systems. Using an innovative numerical technique and a reduced model, we have found that the laser can operate in four different operating regimes when the laser intensity was changed; three of the regimes were experimentally observed in a laser with a sigma configuration. An excellent quantitative agreement between the theoretical and the experimental results was obtained. The use of dispersion management in the sigma laser was found to significantly improve the laser performance.

High-power superfluorescent fiber source

The output of a broad-stripe laser diode is used to pump a neodymium-doped offset core fiber to produce over 80 mW of superfluorescent emission. The power dependence of the spectral bandwidth shows a minimum near 10 mW that increases to 5 nm at 80 mW. Above 15 mW, obtaining a smooth spectrum depended on the specific configuration.