Multimode optical fiber coupler and fabrication method

An optical fiber coupler. comprising:

• a plurality of optical fibers;
• and
• a fused section formed by fusing sections from said optical fibers together;
• wherein:
• each of said optical fibers optically couples with at least one other said optical fiber through surface interaction type optical coupling in said fused section;
• at least one of said optical fibers is suitable for multimode operations;
• at least one of said optical fibers comprises an expanded core section;
• at least a portion of said expanded core section is in said fused section;
• the core diameter of said expanded core section of said optical fiber is different from the core diameter of at least one other said optical fibers;
• and
• at least one of said optical fibers comprises an expanded core section extending from and beyond said fused section along said optical fiber in at least one direction.

An optical fiber coupler, comprising:

• a plurality of optical fibers;
• and
• a fused section formed by fusing sections from said optical fibers together;
• wherein:
• each of said optical fibers optically couples with at least one other said optical fiber through surface interaction type optical coupling in said fused section;
• at least one of said optical fibers is suitable for multimode operations;
• at least one of said optical fibers comprises an expanded core section;
• at least a portion of said expanded core section is in said fused section;
• the core diameter of said expanded core section of said optical fiber is different from the core diameter of at least one other said optical fibers;
• at least one of said optical fibers comprises an expanded core section extending from and beyond said fused section alone said optical fiber in at least one direction;
• and.
• each of said optical fibers is suitable for multimode operations and further comprises an expanded core section.

An optical fiber coupler, comprising:

• a plurality of optical fibers;
• and
• a fused section formed by fusing sections from said optical fibers together;
• wherein:
• each of said optical fibers optically couples with at least one other said optical fiber through surface interaction type optical coupling in said fused section;
• at least one of said optical fibers is suitable for multimode operations;
• at least one of said optical fibers comprises an expanded core section;
• at least a portion of said expanded core section is in said fused section;
• the core diameter of said expanded core section of said optical fiber is different from the core diameter of at least one other said optical fibers;
• the core diameter of at least one of said optical fibers is substantially different from the core diameter of at least one of other said optical fibers at an end of said fused section;
• said optical fiber coupler is suitable for uneven optical coupling operations;
• said expanded core section comprises a thermally expanded core section;
• and
• at least one of said optical fibers comprises an expanded core section extending from and beyond said fused section along said optical fiber in at least one direction.

An optical fiber coupler, comprising:

• a plurality of optical fibers;
• and
• a fused section formed by fusing sections from said optical fibers together;
• wherein:
• each of said optical fibers optically couples with at least one other said optical fiber through surface interaction type optical coupling in said fused section;
• at least one of said optical fibers is suitable for multimode operations;
• at least one of said optical fibers comprises an expanded core section;
• at least a portion of said expanded core section is in said fused section;
• and
• at least a portion of said expanded core section extends from and beyond said fused section along said optical fiber in at least one direction.

An optical fiber coupler, comprising:

• a first multimode optical fiber having a first section;
• and
• a second multimode optical fiber having a second section fused with said first section forming a fused section;
• wherein:
• said first multimode optical fiber and said second multimode optical fiber optically couple through surface interaction type optical coupling in said fused section;
• at least one of said multimode optical fibers comprises an expanded core section;
• the core diameter of said expanded core section of said multimode optical fiber is different from the core diameter of the other multimode optical fiber;
• at least a portion of said expanded core section is in said fused section;
• and
• at least one of said multimode optical fibers comprises an expanded core section extending from and beyond said fused section along said multimode optical fiber in at least one direction.

A method of fabricating an optical fiber coupler, comprising:

• providing a plurality of optical fibers with at least one of said optical fibers having at least an expanded core section and at least one of said optical fibers being suitable for multimode operations;
• and
• maintaining sections of said optical fibers in contact and simultaneously heating at least a portion of said sections that are in contact to form a fused section until a predetermined end condition is reached so that at least a portion of said expanded core section of at least one of said optical fibers is in said fused section;
• wherein each of the optical fibers optically couples with at least one other said optical fiber through surface interaction type optical coupling in said fused section and at least a portion of said expanded core section extends from and beyond said fused section.

A method of fabricating an optical fiber coupler, comprising:

• providing a plurality of optical fibers with at least one of said optical fibers having at least an expanded core section and at least one of said optical fibers being suitable for multimode operations;
• maintaining sections of said optical fibers in contact and simultaneously heating at least a portion of said sections that are in contact to form a fused section until a predetermined end condition is reached so that at least a portion of said expanded core section of at least one of said optical fibers is in said fused section;
• wherein each of the optical fibers optically couples with at least one other said optical fiber through surface interaction type optical coupling in said fused section and
• heating said optical fibers so that a section of the core of at least one of said optical fibers extending from and beyond said fused section along said optical fiber in at least one direction thermally expands.

A method of fabricating an optical fiber coupler, comprising:

• providing a plurality of optical fibers with at least one of said optical fibers having at least an expanded core section and at least one of said optical fibers being suitable for multimode operations;
• maintaining sections of said optical fibers in contact and simultaneously heating at least a portion of said sections that are in contact to form a fused section until a predetermined end condition is reached so that at least a portion of said expanded core section of at least one of said optical fibers is in said fused section;
• and
• heating said optical fibers so that a section of the core of at least one of said optical fibers extending from and beyond said fused section alone said optical fiber in at least one direction thermally expands;
• wherein, said heating terminates after a condition selected from a set of conditions consisting of:
• said optical fiber coupler substantially reaches a predetermined set of optical characteristics, said fused section is substantially over-fused, said heating substantially completes a predetermined temperature profile, said optical fiber coupler substantially reaches a predetermined set of physical characteristics, and said fused section substantially reaches a predetermined length.

A method of fabricating an optical fiber coupler, comprising:

• providing a plurality of optical fibers with at least one of said optical fibers having at least an expanded core section and at least one of said optical fibers being suitable for multimode operations;
• maintaining sections of said optical fibers in contact and simultaneously heating at least a portion of said sections that are in contact to form a fused section until a predetermined end condition is reached so that at least a portion of said expanded core section of at least one of said optical fibers is in said fused section;
• heating said optical fibers so that a section of the core of at least one of said optical fibers extending from and beyond said fused section alone said optical fiber in at least one direction thermally expands;
• and
• pretreating a section of at least one of said optical fibers before said maintaining said expanded core sections of said plurality of optical fibers in contact;
• wherein:
• at least a portion of the pretreated section is in said fused section;
• and
• the method of pretreating a section of an optical fiber comprises a method selected from a set of methods consisting of:
• chemical etching, mechanical abrasion, and elongation under high temperatures.

A method of fabricating an optical fiber coupler, comprising:

• providing a plurality of optical fibers with at least one of said optical fibers having at least an expanded core section and at least one of said optical fibers being suitable for multimode operations;
• maintaining sections of said optical fibers in contact and simultaneously heating at least a portion of said sections that are in contact to form a fused section until a predetermined end condition is reached so that at least a portion of said expanded core section of at least one of said optical fibers is in said fused section;
• and
• heating said optical fibers so that a section of the core of at least one of said optical fibers extending from and beyond said fused section alone said optical fiber in at least one direction thermally expands;
• wherein, the method of maintaining said sections of said optical fibers in contact comprises a method selected from a set of methods consisting of:
• applying tension to at least one of said optical fibers from the two sides of said fused section, vertically stacking said sections that are in contact, laying said sections that are in contact side-by-side, twisting said sections that are in contact together, and forcing said sections that are in contact together with a fixture.