Chiral fiber laser apparatus and method

An apparatus for customizing a chiral fiber laser for lasing and at desired lasing wavelength, comprising:

• means for selecting:
• (1) an optical fiber core having cross-section shape with 180 degree symmetry, a core length, a core height, a core width, and a core refractive index, and,
• (2) a cladding for surrounding said core, having a cladding refractive index, wherein active dopant is disposed throughout at least one of said core and the cladding,
• means for determining a value of a desired pitch to be applied to said core given said desired lasing wavelength, said core cross-section shape, said core length, core height and core width, a core refractive index, and a cladding refractive index, such that when said core is twisted at said desired pitch, a resulting chiral optical fiber will be configured to comprise a photonic stop band with a plurality of long-lived photonic modes occurring therein, wherein a selected long-lived photonic mode of said plural long-lived photonic modes corresponds to said desired lasing wavelength;
• means for applying said desired pitch to said core to produce said chiral optical fiber;
• and
• excitation means, applied to said chiral optical fiber, for causing said chiral optical fiber to emit electromagnetic radiation, wherein said active dopant is configured to produce peak gain substantially positioned at said selected long-lived photonic mode, such that lasing output occurs at said desired lasing wavelength with at least one of:
• a maximum output power and a minimized lasing threshold.

A method for lasing utilizing a chiral fiber structure comprising the steps of:

• (a) providing an elongated chiral optical fiber comprising a photonic stop band with a plurality of long-lived photonic modes occurring therein, said chiral optical fiber having a central longitudinal axis, a core disposed along said longitudinal axis, said core having a pitch, a core cross-section shape with 180 degree symmetry, a core length, a core height, a core width, and a core refractive index, and a cladding surrounding said core having a cladding refractive index,
• (b) prior to said step (a), choosing said core and cladding refractive indices, said core cross-section shape, said core length, said core height, and said core width;
• (c) after said step (b) but prior to said step (a), determining a desired pitch that corresponds to a desired lasing wavelength, from:
• i) said desired lasing wavelength,
• ii) said core and cladding refractive indices, and
• iii) said core cross-section shape, said core length, said core height, and said core width;
• (d) prior to said step (a) configuring said elongated chiral optical fiber with said desired pitch such that said desired lasing wavelength corresponds to a particular long-lived photonic mode from said plural long-lived photonic modes,
• (e) prior to said step (a), choosing and configuring an active dopant disposed within at least one of said core and said cladding, to produce peak gain approximately positioned at said selected particular long-lived photonic mode;
• and
• (f) applying excitation to said chiral optical fiber, to cause said chiral optical fiber to emit electromagnetic radiation, such that lasing output occurs at said desired lasing wavelength with at least one of:
• a maximum output power and a minimized lasing threshold.