Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
189 words
A method of providing adjustable magnitude linear dispersion
of light, in which method light is caused to make a first reflection in a first
optical waveguide (11, 71) provided with an associated first chirped Bragg
grating reflector (13, 73) that exhibits chirp by virtue of having grating
elements at an effective pitch which is a function of position along the
grating, which effective pitch is the product of the physical pitch of the grating
elements at any position along the length of the grating with the refractive
index of the waveguide at that position; which method is characterised in that
the light which makes said first reflection in said first waveguide additionally
makes a second reflection in a second waveguide (12, 72) provided with an
associated second chirped Bragg grating reflector (14, 74) whose chirp is
such that said first and second Bragg grating reflectors have quadratic
components of chirp of opposite sign and substantially matched modulus;
and wherein the aggregate magnitude of linear dispersion afforded to light
making said two reflections is adjustable by effecting a differential scaling of
the effective pitches of the two Bragg grating reflectors.
Claim 2
Dependent Claim
24 words
A method as claimed in claim 1, wherein said differential
scaling is effected by a differential axial straining of the two Bragg grating
reflectors.
Claim 3
Dependent Claim
23 words
A method as claimed in claim 1, wherein said differential
scaling is effected by a differential heating of the two Bragg grating
reflectors.
Claim 4
Dependent Claim
20 words
A method as claimed in claim 1, 2 or 3, wherein the Bragg
grating reflectors are sampled Bragg grating reflectors.
Claim 5
Independent Claim
188 words
A device exhibiting linear dispersion of adjustable magnitude,
which device includes a first optical waveguide (11, 71) provided with an
associated first chirped Bragg grating reflector (13, 73) that exhibits chirp by
virtue of having grating elements at an effective pitch which is a function of
position along the grating, which effective pitch is the product of the physical
pitch of the grating elements at any position along the length of the grating
with the refractive index of the waveguide at that position; which device is
characterised in that it additionally includes a second optical waveguide (12,
72) provided with an associated second chirped Bragg grating reflector (14,
74) whose chirp is such that said first and second Bragg grating reflectors
have quadratic components of chirp of opposite sign and substantially
matched modulus, which first and second waveguides are arranged to define
an optical transmission path in the device that includes a reflection in one
grating and then in the other, and wherein the device includes means (15,
55, 65, 75, 76) to effect a differential scaling of the effective pitches of the
two chirped Bragg grating reflectors.
Claim 6
Dependent Claim
17 words
A device as claimed in claim 5, wherein the Bragg grating
reflectors are sampled Bragg grating reflectors.
Claim 7
Dependent Claim
19 words
A device as claimed in claim 5 or 6, wherein the first and
second waveguides are optical fibre waveguides.
Claim 8
Dependent Claim
48 words
A device as claimed in claim 5, 6 or 7, wherein said means is
a strain applicator (55, 65) mechanically coupled with the first waveguide and
adapted to impart to the first waveguide, over the length of its Bragg grating,
a substantially uniform axial strain of adjustable magnitude.
Claim 9
Dependent Claim
28 words
A device as claimed in claim 8, wherein the strain applicator
(55) imparts adjustable magnitude tensile strain to the first waveguide over
the length of its Bragg grating.
Claim 10
Dependent Claim
28 words
A device as claimed in claim 8, wherein the strain applicator
(65) imparts adjustable magnitude compressive strain to the first waveguide
over the length of its Bragg grating.
Claim 11
Dependent Claim
38 words
A device as claimed in claim 5, 6 or 7, wherein said means is
a thermal regulator (75, 76) adapted to maintain a uniform temperature
difference of adjustable magnitude between said first and second chirped
Bragg reflection gratings.
Claim 12
Dependent Claim
17 words
A device as claimed in claim 11, wherein said first and second
optical waveguides are polymer waveguides.