Apparatus and method for spectral-beam combining of high-power fiber lasers

An apparatus comprising:

• an output diffractive element;
• and
• a source of a plurality of substantially monochromatic light beams directed from different angles to a single location on the output diffractive element, wherein the output diffractive element spectrally combines the plurality of light beams into a single beam, and wherein the plurality of light beams includes a first light beam having a first central wavelength and a second light beam having a second central wavelength;
• a first adjustment apparatus configured to set an adjustable characteristic of the first light beam;
• a second adjustment apparatus configured to set an adjustable characteristic of the second light beam;
• a detector configured to detect whether one of the light beams has become misaligned relative to the single combined beam;
• a diagnoser configured to determine whether the first light beam is the misaligned one and if so, to control the first adjustment apparatus to adjust the adjustable characteristic of the first light beam in order that the first light beam becomes aligned relative to the single combined beam;
• a plurality of Yb-doped multiply clad optical fibers including a first fiber and a second fiber each having an inner cladding and one or more outer claddings;
• and
• one or more laser diodes optically coupled to insert their laser outputs as pump light to the inner claddings of the plurality of fibers, wherein the first light beam is a first laser beam and the second light beam is a second laser beam;
• and wherein the first fiber amplifies the first laser beam at a first wavelength, and the second fiber amplifies the second laser beam at a second wavelength.

An apparatus comprising:

• a source of a plurality of light beams including a first laser beam and a second laser beam, wherein the source includes a plurality of optical fibers including a first fiber and a second fiber;
• diffractive means for spectrally combining the plurality of laser beams into a single output beam;
• means for wavelength tuning the first fiber to generate the first laser beam at the first wavelength;
• means for wavelength tuning the second fiber to generate the second laser beam at the second wavelength;
• means for detecting that one of the laser beams has become misaligned relative to the single combined beam;
• means for determining that the first laser beam is the misaligned one;
• and
• means for adjusting the means for wavelength tuning of the first fiber in order that the first laser beam is aligned relative to the single combined beam.

An apparatus comprising:

• a source of a plurality of light beams including a first laser beam and a second laser beam, wherein the source includes:
• a plurality of Yb-doped multiply clad optical fibers including a first fiber and a second fiber;
• means for pumping an inner cladding of the plurality of fibers with pump light from one or more laser diodes;
• means for amplifying with the first fiber a first seed laser beam at a first wavelength for one of the plurality of light beams;
• and
• means for amplifying with the second fiber a second seed laser beam at a second wavelength for another of the plurality of light beams;
• diffractive means for spectrally combining the plurality of laser beams into a single output beam;
• means for wavelength tuning the first fiber to generate the first laser beam at the first wavelength;
• means for wavelength tuning the second fiber to generate the second laser beam at the second wavelength;
• means for detecting that one of the laser beams has become misaligned relative to the single combined beam;
• means for determining that the first laser beam is the misaligned one;
• and
• means for adjusting the means for wavelength tuning of the first fiber in order that the first laser beam is aligned relative to the single combined beam.

An apparatus comprising:

• means for providing a plurality of laser beams including a first laser beam and a second laser beam;
• means for wavelength tuning the first fiber to generate the first laser beam at the first wavelength and having a linewidth of about 1 nm or less;
• means for wavelength tuning the second fiber to generate the second laser beam at the second wavelength and having a linewidth of about 1 nm or less;
• and
• means for spectrally combining the plurality of laser beams into a single output beam having an output power/area of about 10 W/cm2 or more using one or more high-efficiency dielectric diffractive gratings.