Method and apparatus for micromachining bulk transparent materials using localized heating by nonlinearly absorbed laser radiation, and devices fabricated thereby

Apparatus for thermal 3-D micromachining of a photonic structure, comprising:

• a laser system including an oscillator producing a train of laser pulses;
• a substrate holder adapted to receive a substrate having a bulk to be micromachined transparent to said laser pulses;
• and
• means, coupled to said laser system and cooperative with the substrate holder, for directing said train of laser pulses in a focal volume about each of different points in the bulk of the substrate where said photonic structure is to be micromachined (1) with an intensity high enough to cause the bulk confined within the focal volume about each said point to non-linearly absorb energy from the laser pulses and (2) at a rate that delivers the energy of the laser pulses into the focal volume faster than it can diffuse out of the focal volume so as to produce a controlled source of heat in the focal volume about each said point to cause a predetermined alteration of a region of the bulk having a volume greater than the focal volume about each said point.

Apparatus for 3-D thermal micromachining of a photonic structure, comprising:

• a substrate holder adapted to receive a substrate having a bulk to be micromachined;
• means for depositing laser energy by non-linear absorption into a focal volume about each point of the bulk of the substrate to be micromachined at a rate greater than the rate that it diffuses thereout to produce a point source of heat in a region of the bulk larger than the focal volume about each point that structurally alters the region of the bulk larger than the focal volume about each point;
• and
• means for dragging the point source of heat thereby provided point-to-point along any linear and non-linear path to fabricate said photonic structure in the bulk of the substrate.