Apparatus and method for generating 780 nm ultrashort-pulsed laser radiation
AssigneeCoherent Scotland Limited
InventorLee Cairns
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Abstract
An erbium fiber laser produces a beam of ultrashort laser pulses having a center wavelength greater than 780 nanometers, an average power greater than 0.5 watt, and a pulse duration less than 200 femtoseconds. The fiber laser includes an erbium fiber amplifier that is energized by a pump beam having a pump wavelength longer than 1520 nanometers. The pump wavelength is selected to provide uniform gain over the broad spectral bandwidth of a seed beam and minimal gain at shorter wavelengths in the fiber amplifier, thereby overcoming gain narrowing and gain shifting. The pump beam has sufficient power to achieve pump saturation in the fiber amplifier.
Claims20
An ultrashort-pulsed laser, comprising:
- a seed laser for generating a pulsed signal beam;
- an optical resonator for generating a pump beam having a pump wavelength greater than or equal to 1520 nanometers;
- a power amplifier doped with erbium ions, the power amplifier arranged to receive the signal beam from the seed laser and the pump beam from the optical resonator, the erbium ions in a gain volume of the power amplifier energized by the pump beam, the pump beam causing pump saturation and producing a population inversion within the gain volume less than or equal to 57%, the power amplifier generating an amplified signal beam;
- a pulse compressor for temporally compressing pulses in the amplified signal beam;
- and
- a harmonic generator arranged to receive the amplified and compressed signal beam, the harmonic generator generating a second-harmonic beam having a center wavelength greater than or equal to 780 nanometers and a pulse duration less than or equal to 200 femtoseconds.
A method for generating an ultrashort-pulsed output laser beam, comprising the steps of:
- generating a pulsed signal beam;
- generating a pump beam in an optical resonator, the pump beam having a pump wavelength greater than or equal to 1520 nanometers;
- delivering the signal beam and the pump beam to a power amplifier doped with erbium ions, the pump beam energizing the erbium ions in a gain volume of the power amplifier, causing pump saturation and producing a population inversion within the gain volume less than or equal to 57%, the power amplifier generating an amplified signal beam;
- temporally compressing pulses in the amplified signal beam;
- and
- converting the amplified and compressed signal beam to the output laser beam by second-harmonic generation, the output laser beam having a center wavelength greater than or equal to 780 nanometers and a pulse duration less than or equal to 200 femtoseconds.
Dependencies are inferred from the claim text.