Thin walled core band-gap waveguides

A method of making a photonic band-gap crystal waveguide fiber comprising the steps:

• a) assembling into a bundle a first plurality of tubes to form a first portion of a photonic crystal, a group of tubes of said first plurality of tubes having a wall thickness which varies along the tube circumference to provide thinner and thicker wall portions of the tubes of the group, wherein, said first plurality of tubes is assembled into said bundle so that thinner wall portions of neighboring tubes abut one another;
• b) assembling a second plurality of tubes about said bundle to form a second portion of the photonic crystal, each of the second plurality of tubes having a substantially uniform wall thickness;
• c) etching the walls of said first and second plurality of tubes to etch away the abutting thinner wall portions to form a defect in the photonic crystal, said first and second plurality of tubes each having a long axis, and, said photonic crystal having a cross section perpendicular to the long axis;
• and,
• d) after step c) reducing in area a cross section of said photonic crystal, wherein the cross section is perpendicular to the long axes of each of the first and second plurality of tubes, to form a waveguide fiber.

A method of making a photonic crystal waveguide fiber preform comprising the steps:

• a) forming a photonic crystal having a plurality of openings, separated one from another by walls, extending from a first to a second end of said photonic crystal;
• b) etching the walls to remove material therefrom;
• wherein,
• the plurality of openings is divided into a first and a second group, each said group having walls, said first group being contiguous and surrounded by said second group, and having walls of a first composition characterized by a first etch rate, said second group having walls of a second composition characterized by a second etch rate, wherein the first etch rate is greater than the second etch rate.