Seeder for use with a fiber laser for generating an arbitrary shaped pulse, comprising an amplified spontaneous emission (ASE) source, a spectral filter and an arbitrary waveform generator (AWG) modulator, the ASE source for generating a continuous wave (CW) broadband pulse, the spectral filter being coupled with the ASE source for narrowing the CW broadband pulse, and the AWG modulator being coupled with the spectral filter for shaping the narrowed CW broadband pulse to an arbitrary pulse shape.

An amplified spontaneous emission (ASE) light source and a method for using the ASE light source are provided. The ASE light source may include a seed stage light source for providing a light beam to be amplified. The apparatus may include a tunable element coupled to the seed stage light source configured for filtering a portion of the light beam from the seed stage light source. The apparatus may include a loopback circuit coupled to the tunable element, the loopback circuit comprising a booster stage element for amplifying light from the tunable element.

An amplified spontaneous emission (ASE) light source and a method for using the ASE light source are provided. The ASE light source may include a seed stage light source for providing a light beam to be amplified. The apparatus may include a tunable element coupled to the seed stage light source configured for filtering a portion of the light beam from the seed stage light source. The apparatus may include a loopback circuit coupled to the tunable element, the loopback circuit comprising a booster stage element for amplifying light from the tunable element.

A laser system includes a laser device configured to output pulse laser light, and a first optical pulse stretcher including a delay optical path for stretching a pulse width of the pulse laser light. The first optical pulse stretcher is configured to change a beam waist position of circulation light that circulates through the delay optical path and is output therefrom, in an optical path axis direction according to a circulation count. When the circulation light is condensed by an ideal lens, a light condensing position of the circulation light is changed in the optical path axis direction according to the circulation count.

A gas detection system uses intracavity fiber laser absorption spectroscopy. The fiber laser is stabilized by a saturable absorber, and the sensitivity is enhanced by multiple circulations of amplified spontaneous emission light under threshold conditions, and multi-longitudinal mode oscillation of the laser.

A gas detection system uses intracavity fiber laser absorption spectroscopy. The fiber laser is stabilized by a saturable absorber, and the sensitivity is enhanced by multiple circulations of amplified spontaneous emission light under threshold conditions, and multi-longitudinal mode oscillation of the laser.