US 7,018,745 B2Granted

Controlled phase delay between beams for writing bragg gratings

AssigneeThe University of Sydney

InventorsDmitrii Stepanov, Mark Sceats

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Abstract

A method of writing an extended grating structure in a photosensitive waveguide comprising the steps of utilizing at least two overlapping beams of light to form an interference pattern, moving the waveguide through said overlapping beams, simultaneously controlling a relative phase delay between the beams utilising a phase modulator, thereby controlling the positions of maxima within said interference pattern to move at approximately the same velocity as the photosensitive waveguide, wherein the phase modulator does not comprise a mechanical means for effecting the phase modulation, and modifying the relative phase delay between the beams during the writing of the grating structure, whereby a deliberate detuning of the velocity of the positions of maxima within said interference pattern and the velocity of the photosensitive waveguide is utilized to vary a period of the written grating structure in the photosensitive waveguide.

Claims15

Dependent claims

A method of writing an extended grating structure in a photosensitive waveguide comprising:

utilising at least two overlapping beams of light to form an interference pattern,
moving the waveguide through an overlap region defined by said overlapping beams,
simultaneously varying the phase of at least one of the beams relative to at least one of the other beams utilising a phase modulator,
thereby variably controlling the velocity of the maxima within said interference pattern so that such velocity is different from the velocity of the photosensitive waveguide within the overlap region for the duration of the writing, excluding any periods of velocity change when the velocity of said maxima momentarily equals the velocity of the waveguide, wherein:
the phase modulator comprises a non-mechanical means for effecting the phase modulation, and
variation of the velocity of the maxima within the overlap region relative to the photosensitive waveguide is utilised to vary at least one of the phase, amplitude and period properties of at least a portion of the extended grating structure in the photosensitive waveguide.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/338,884Filed 9 Jan 2003 · continuation
Priority: AU PP381629 May 1998
Published: US 2003/0124438 A13 Jul 2003
Granted: 28 Mar 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G02B 6/02152
Characterised by the method of manufacture of the grating: involving moving the fibre or a manufacturing element, stretching of the fibre
G02B 5/1857
Manufacturing methods: using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
G02B 6/02133
Characterised by the method of manufacture of the grating: using beam interference
G02B 6/02138
Using beam interference: based on illuminating a phase mask