Reduction of pulsations in DFB lasers
AssigneeThe University of Sydney
InventorsDmitrii Stepanov, Zourab Brodzeli
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Abstract
Output power fluctuations in a distributed feedback laser arrangement are reduced by inducing a saturable absorption grating in a saturable absorption region. Light is coupled into a DFB region and amplified in an amplification region. A feedback loop reflects a portion of the amplified light, and the counter-propagating beams induce an absorption grating in a saturable absorption region which suppresses output oscillations. The amplification region can comprise an erbium doped fiber, and the saturable absorption region can comprise an underpumped portion of such a fiber, or a further length of such fiber, or a planar waveguide.
Claims19
A method of reducing power fluctuations in an output of a laser, the method comprising the steps of:
- generating a laser signal utilizing a distributed feedback laser cavity,
- redirecting a signal portion of th)e laser signal back towards the laser cavity, and
- inducing a saturable absorption grating in a saturable absorption element external to the laser cavity in the optical path of the laser signal as a result of wave mixing of the laser signal and the redirected signal portion,
- whereby, in use, phase-discriminating properties of the induced saturable absorption grating in the optical path of the laser signal provide a phase-conjugated feedback signal for introduction into the laser cavity for reducing power fluctuations in an optical output of the laser cavity.
A laser structure comprising:
- a distributed feedback laser cavity for generating a laser signal,
- an optical signal redirecting element external to the laser cavity and disposed in the optical path of the laser signal for redirecting a signal portion of the laser signal back towards the laser cavity, and
- a saturable absorption element external to the laser cavity and disposed in the optical paths of the laser signal and of the redirected signal portion for inducing a saturable absorption grating in the saturable absorption element in the optical path of the laser signal as a result of wave mixing of the laser signal and the redirected signal portion,
- whereby, phase-discriminating properties of the induced saturable absorption grating in the optical path of the laser signal provide a phase-conjugated feedback signal for introduction into the laser cavity for reducing power fluctuations in an optical output of the laser cavity.
An external feedback device for a distributed feedback laser cavity, the feedback device comprising:
- an interconnecting element for coupling a laser signal from an output of the distributed feedback laser cavity into the external feedback device,
- an optical signal redirecting element disposed in the optical path of the laser signal within the external feedback device for redirecting a signal portion of the laser signal back towards the interconnecting element, and
- a saturable absorption element disposed in the optical paths of the laser signal and of the redirected signal portion within the external feedback device for inducing a saturable absorption grating in the saturable absorption element in the optical path of the laser signal as a result of wave mixing of the laser signal and the redirected signal portion,
- whereby, the external feedback device is arranged in a manner such that phase-discriminating properties of the induced saturable absorption grating in the optical path of the laser signal provide to the interconnecting element a phase-conjugated feedback sill for introduction into the laser cavity for reducing power fluctuations in the optical output of the laser cavity.
Dependencies are inferred from the claim text.