Optical fiber lasers and amplifiers

An optical fiber which comprises:

• a substantially single-mode core having an index of refraction n.sub.1 comprised of laser material disposed within a multi-mode cladding having an index of refraction n.sub.2 ;
• and
• a further cladding having an index of refraction n, surrounding said multi-mode cladding with substantially no space between said further cladding and said multi-mode cladding;
• wherein the cross-sectional area of said multi-mode cladding taken substantially transverse to the axial extent of the optical fiber has a first path across said area which passes substantially through the geometric center thereof whose length is substantially different from the length of a second path across said area which passes substantially through the geometric center thereof, said second path being substantially perpendicular to said first path and
• n.sub.1 >n.sub.2 >n.sub.3.

An apparatus comprising:

• a first fiber which comprises a substantially single-mode core having an index of refraction n.sub.1 comprised of laser material disposed within a multi-mode cladding having an index of refraction n.sub.2 and a further cladding having an index of refraction n.sub.3 , surrounding said multi-mode cladding with substantially no space between said further cladding and said multi-mode cladding;
• wherein the cross-sectional area of said multi-mode cladding taken substantially transverse to the axial extent of the first fiber has a first path across said area which passes substantially through the geometric center thereof whose length is substantially different from the length of a second path across said area which passes substantially through the geometric center thereof, said second path being substantially perpendicular to said first path, said further cladding does not completely surround said multi-mode cladding along at least one portion of the axial extent of said first fiber, and ps
• n.sub.1 >n.sub.2 >n.sub.3 ;
• and
• a second fiber which comprises a multi-mode waveguide and another further cladding surrounding said multi-mode waveguide with substantially no space between the another further cladding and the multi-mode waveguide;
• wherein the cross-sectional area of said multi-mode waveguide taken substantially transverse to the axial extent of said second fiber has a first path across said area which passes substantially through the geometric center thereof whose length is substantially different from the length of a second path across said area which passes substantially through the geometric center thereof, said second path being substantially perpendicular to said first path, said another further cladding does not completely surround said multi-mode waveguide along at least one portion of the axial extent of said second fiber;
• and
• said multi-mode cladding is affixed to said waveguide along at least one of the at least one portion of the first and second fibers.

An apparatus comprising:

• a fiber which comprises a substantially single-mode core having an index of refraction n.sub.1 comprised of laser material disposed within a multi-mode cladding having an index of refraction n.sub.2 and a further cladding having an index of refraction n.sub.3 surrounding said multi-mode cladding with substantially no space between said further cladding and said multi-mode cladding;
• wherein the cross-sectional area of said multi-mode cladding taken substantially transverse to the axial extent of the fiber has a first path across said area which passes substantially through the geometric center thereof whose length is substantially different from the length of a second path across said area which passes substantially through the geometric center thereof, said second path being substantially perpendicular to said first path, said further cladding does not completely surround said multi-mode cladding along at least one portion of the axial extent of said fiber, and
• n.sub.1 >n.sub.2 >n.sub.3 ;
• and
• at least one coupling means is affixed to said multi-mode cladding along at least one of the at least one portion of said first fiber for coupling radiation into said multi-mode cladding.

An apparatus comprising:

• a first fiber which comprises a substantially single-mode core having an index of refraction n.sub.1 comprised of laser material disposed within a multi-mode cladding having an index of refraction n.sub.2 and a further cladding having an index of refraction n.sub.3 surrounding said multi-mode cladding with substantially no space between said further cladding and said multi-mode cladding;
• wherein the cross-sectional area of said multi-mode cladding taken substantially transverse to the axial extent of the fiber has a first path across said area which passes substantially through the geometric center thereof whose length is substantially different from the length of a second path across said area which passes substantially through the geometric center thereof, said second path being substantially perpendicular to said first path said further cladding does not completely surround said multi=mode cladding along a portion of the axial extend of said first fiber, and
• n.sub.1 >n.sub.2 >n.sub.3 ;
• and
• a second fiber which comprises a multi-mode waveguide and another further cladding surrounding said multi-mode waveguide with substantially no space between said further cladding and said multi-mode waveguide;
• wherein the cross-sectional area of said multi-mode waveguide taken substantially transverse to the axial extent of the fiber has a first path across said area which passes substantially through the geometric center thereof whose length is substantially different from the length of a second path across said area which passes substantially through the geometric center thereof, said second path being substantially perpendicular to said first path, and one end of said second fiber is formed into a wedge;
• and
• said multi-mode cladding is affixed to the wedge at the end of said waveguide along said portion of the first fiber.