Abstract: A laser apparatus operable to generate giant chirp pulses. The pulses have a centre frequency comprising an arrangement of components connected or connectable to form a closed ring cavity. The components comprise a first gain medium, an optical isolator, a length of single mode fibre, a mode locking device, an output coupler, and an optical filter. Each of the components are optical fibre based components.

Abstract: A laser apparatus operable to generate giant chirp pulses. The pulses have a center frequency comprising an arrangement of components connected or connectable to form a closed ring cavity. The components comprise a first gain medium, an optical isolator, a length of single mode fiber, a mode locking device, an output coupler, and an optical filter. Each of the components are optical fiber based components.

Abstract: A laser apparatus operable to generate giant chirp pulses. The pulses have a centre frequency comprising an arrangement of components connected or connectable to form a closed ring cavity. The components comprise a first gain medium, an optical isolator, a length of single mode fibre, a mode locking device, an output coupler, and an optical filter. Each of the components are optical fibre based components.

Abstract: To overcome problems of fabricating conventional core-clad optical fibre from non-silica based (compound) glass, it is proposed to fabricate non-silica based (compound) glass optical fibre as holey fibre i.e. one contining Longitudinal holes in the cladding. This removes the conventional problems associated with mismatch of the physical properties of the core and clad compound glasses, since a holey fibre can be made of a single glass composition. With a holey fibre, it is not necessary to have different glasses for the core and cladding, since the necessary refractive index modulation between core and cladding is provided by the microstructure of the clad, i.e. its holes, rather than by a difference in materials properties between the clad and core glasses. Specifically, the conventional thermal mismatch problems between core and clad are circumvented.

Abstract: An optical fibre has a cladding layer surrounding a core, the cladding layer comprising at least a first, relatively inner generally cylindrical region, a third, relatively outer generally cylindrical region, and a second region disposed between the first and third regions, the second region having a higher refractive index than the first and third regions; and the peak difference in refractive index between the first cladding region and the core being less than about 0.0030.

Abstract: To overcome problems of fabricating conventional core-clad optical fibre from non-silica based (compound) glass, it is proposed to fabricate non-silica based (compound) glass optical fibre as holey fibre i.e. one contining Longitudinal holes in the cladding. This removes the conventional problems associated with mismatch of the physical properties of the core and clad compound glasses, since a holey fibre can be made of a single glass composition. With a holey fibre, it is not necessary to have different glasses for the core and cladding, since the necessary refractive index modulation between core and cladding is provided by the microstructure of the clad, i.e. its holes, rather than by a difference in materials properties between the clad and core glasses. Specifically, the conventional thermal mismatch problems between core and clad are circumvented.

Abstract: The percentage fraction of fundamental mode power located in the cladding holes of different holey fibers (PFholes) is shown as a function of wavelength in microns of the fundamental mode (&lgr;). Properties of two groups of holey fibers are shown. The upper group of three curves shows embodiments of the invention with &Lgr;=0.75 &mgr;m and d/&Lgr;=0.6, 0.7 & 0.8 respectively, where d is the hole diameter and &Lgr; the hole spacing or pitch. The lower group of curves, which are almost superimposed on each other, show properties of holey fibers representative of the prior art with &Lgr;=3.2 &mgr;m and d/&Lgr;=0.6, 0.7 & 0.8 respectively. A huge improvement in the mode power present in the holes is evident. In the prior art curves, the mode power fraction is generally less than 1%, whereas with the illustrated embodiments of the invention, holey fibers with 10-40% of the fundamental mode power in the holes are achieved.

Abstract: The percentage fraction of fundamental mode power located in the cladding holes of different holey fibers (PFholes) is shown as a function of wavelength in microns of the fundamental mode (&lgr;). Properties of two groups of holey fibers are shown. The upper group of three curves shows embodiments of the invention with &Lgr;=0.75 &mgr;m and d/&Lgr;=0.6, 0.7 & 0.8 respectively, where d is the hole diameter and &Lgr; the hole spacing or pitch. The lower group of curves, which are almost superimposed on each other, show properties of holey fibers representative of the prior art with &Lgr;=3.2 &mgr;m and d/&Lgr;=0.6, 0.7 & 0.8 respectively. A huge improvement in the mode power present in the holes is evident. In the prior art curves, the mode power fraction is generally less than 1%, whereas with the illustrated embodiments of the invention, holey fibers with 10-40% of the fundamental mode power in the holes are achieved.

Abstract: An optical fibre has a cladding layer surrounding a core, the cladding layer comprising at least a first, relatively inner generally cylindrical region, a third, relatively outer generally cylindrical region, and a second region disposed between the first and third regions, the second region having a higher refractive index than the first and third regions; and the peak difference in refractive index between the first cladding region and the core being less than about 0.0030.