Optical scheme for holographic imaging of complex diffractive elements in materials

A method for writing a spatial modulated index pattern in a material that is at least partially transmissive or partially absorbing comprising the steps of:

• a) providing a pulse of laser light from an ultrafast laser;
• b) providing a diffractive optic element having predetermined characteristics and directing the short pulse of laser light to be incident upon the diffractive optic element;
• c) disposing an imaging and concentrating system to receive multiple light beams diffracted from the diffractive optic element and for concentrating the light beams received at the material, step (c) including the sub-steps of:
• i) said imaging and concentrating system including a curved mirror for reflecting the multiple light beams from the diffractive optic element in a substantially wavelength independent manner;
• and
• ii) said imaging and concentrating system including means for receiving the light beams reflected from the curved mirror and concentrating and focusing said light beams received from the curved mirror onto the light transmissive material to effect a permanent refractive index change within the material that corresponds to the spatial modulated light pattern, said curved mirror and said means for receiving and concentrating are positioned relative to each other so as to affect each of the multiple light beams in substantially the same way for preserving a stable phase relationship between said multiple light beams at said material.

A method of effecting a refractive index change in a sample that is at least partially transmissive or partially absorbing comprising the steps of:

• providing a short pulse laser beam having a low power per unit area to a diffractive optical element so as to irradiate the diffractive optical element;
• collecting light from the diffractive optical element while preserving an image relating to characteristics of the diffractive optical element encoded within the light collected;
• and
• directing the light collected in wavelength independent manner to the sample while preserving the image of the diffractive optical element encoded within the light collected and demagnifying the image within the light collected so as to increase its power per unit area when directed to the sample to be permanently impressed therein, wherein the steps of collecting the light from the diffractive optical element and directing the light collected in wavelength independent manner includes preserving a stable phase relationship between components of the light collected.

A method for producing multiple light beams from an ultrafast laser with interferometric stability between the multiple beams, comprising the steps of:

• a) providing a pulse of laser light from an ultrafast laser;
• b) providing a diffractive optic element having predetermined characteristics and directing the pulse of laser light to be incident upon the diffractive optic element;
• and
• c) capturing and reflecting multiple light beams diffracted from the diffractive optic element in a substantially wavelength independent manner, said multiple light beams being captured and reflected using optical elements which are positioned relative to each other and to said diffractive optic element so as to affect each of the multiple light beams in substantially the same way for preserving a stable phase relationship therebetween.