Bragg grating structure
First Claim
1. A chirped Bragg grating having a local reflection strength which varies with position along the length of the grating so as to generate an overall reflection strength spectrum which is non-uniform with respect to wavelength between two wavelength extremities, andcomprising:
- a periodic pattern of marks and spaces whose period varies along the length of the grating; and
one or more reduced reflective strength regions, each reduced reflective strength region formed by the base order periodic pattern of marks and spaces from which at least some of the marks are missing.
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Accused Products
Abstract
A Bragg grating has a local reflection strength which varies with position along the length of the grating so as to generate a non-uniform wavelength reflection spectrum, enabling compensation for a non-uniform gain profile of the gain section of a tunable laser. In another aspect, a Bragg comb grating is modulated by an envelope function which can also compensate for a non-uniform gain profile. The comb grating may be a phase change grating, with the envelope function shape being controlled by the length between phase changes and/or size of the phase changes.
34 Citations
15 Claims
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1. A chirped Bragg grating having a local reflection strength which varies with position along the length of the grating so as to generate an overall reflection strength spectrum which is non-uniform with respect to wavelength between two wavelength extremities, and
comprising: - a periodic pattern of marks and spaces whose period varies along the length of the grating; and
one or more reduced reflective strength regions, each reduced reflective strength region formed by the base order periodic pattern of marks and spaces from which at least some of the marks are missing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- a periodic pattern of marks and spaces whose period varies along the length of the grating; and
- 10. A Bragg grating adapted to produce a reflection spectrum comprising a comb of reflective peaks at discrete wavelengths, the peaks having reflection amplitudes modulated by an envelope function which is non-uniform between two wavelength extremities, the grating comprising a plurality of periodic grating sections separated by phase changes, the lengths of the grating sections being chosen so that the envelope function includes maxima at the two wavelength extremities.
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15. A method of manufacturing a chirped Bragg grating having a non-uniform wavelength reflection spectrum, the method comprising varying the reflection strength along the length of the grating by forming a periodic pattern of marks and spaces whose period varies along the length of the grating;
- and one or more reduced reflective strength regions, each reduced reflective strength region formed by the base order periodic pattern of marks and spaces from which at least some of the marks are missing.
Specification