Abstract: A method for a defined deposition of a glass layer on an inner wall of a preform for an optical fiber and/or for setting a refractive index profile of the preform for a multi-mode fiber. The method includes providing the preform having a cavity and an inner wall which defines an inner diameter of the preform, and spreading a deposition gas at a flow speed (v) in the cavity of the preform so as to provide the defined deposition of the glass layer. The defined deposition is performed at a reduced change in the flow speed a*?v, where a<1. Based on the defined deposition, a change in the flow speed (?v): ? ? ? v = 4 ? ? Q ? · ( 1 d i 2 - 1 d i + 1 2 ) forms at a volume flow (Q), a first diameter (di), and a second diameter (di+1).

Abstract: A method for a defined deposition of a glass layer on an inner wall of a preform for an optical fiber and/or for setting a refractive index profile of the preform for a multi-mode fiber. The method includes providing the preform having a cavity and an inner wall which defines an inner diameter of the preform, and spreading a deposition gas at a flow speed (v) in the cavity of the preform so as to provide the defined deposition of the glass layer. The defined deposition is performed at a reduced change in the flow speed a*?v, where a<1. Based on the defined deposition, a change in the flow speed (?v): ? ? ? v = 4 ? ? Q ? · ( 1 d i 2 - 1 d i + 1 2 ) forms at a volume flow (Q), a first diameter (di), and a second diameter (di+1).

Abstract: Methods for making a preform for a graded-index multimode fiber by using an inside deposition process are disclosed. The methods are characterized by an iterative refractive index profile correction with the following steps: determining a target refractive index profile for the preform to be produced, carrying out an inside deposition process with fixed volume flows for the reacting gases inside a tube and a given burner speed for all deposited layers, collapsing the tube and measuring the actual refractive index profile, comparing the target profile with the actual profile and calculating a correction value of index differences, converting this correction value in corrected burner speeds as varying process parameter, carrying out a inside deposition process with fixed gas flows and corrected burner speeds for all layers to be deposited.

Abstract: The invention relates to a bend insensitive gradient index multi-mode light conducting fiber comprising a leakage mode dependent optical core diameter that is uniform over its length and a numerical aperture that is uniform over its length, wherein for a light wavelength of 850 nm and an overfilled launch (OFL), the optical core diameter for a fiber length in a range between 2 m and 100 m decreases by less than 5% and the numerical aperture decreases by less than 2.5% and the curvature related attenuation increase for two turns and a curvature radius of 7.5 mm is less than 0.2 db.

Abstract: The invention relates to a bend insensitive gradient index multi-mode light conducting fiber comprising a leakage mode dependent optical core diameter that is uniform over its length and a numerical aperture that is uniform over its length, a core (1), an inner cladding (2), a refraction index trench (3) and an outer cladding (4), wherein the core (1) includes a core radius R1, an alpha-refraction index profile and a core refraction index difference dn1 with respect to the outer cladding (4), wherein the refraction index trench (3) includes a refraction index trench radius R3 and a trench refraction index difference dn3 with respect to the outer cladding (4), wherein the outer cladding (4) includes an outer cladding radius R4 and a refraction index between 1.40 and 1.55, wherein for a light wavelength of 850 nm and a full core excitation (OFL), the optical core diameter for a fiber length in a range between 2 m and 300 m decreases by less than 5% and the numeric aperture decreases by less than 2.

Abstract: The invention relates to a bend insensitive gradient index multimode light conducting fiber comprising a leakage mode dependent optical core diameter that is uniform over its length and numerical aperture that is uniform over its length, a core (1), an inner cladding (2), a refraction index trench (3) and an outer cladding (4), wherein the core (1) includes a core radius R1, an alpha-refraction index profile and a core refraction index difference dn1 with respect to the outer cladding (4), wherein the refraction index trench (3) includes a refraction index trench radius R3 and a trench refraction index difference dn3 with respect to the outer cladding (4), wherein the outer cladding (4) includes an outer cladding radius R4 and a refraction index between 1.40 and 1.55, wherein for a light wavelength of 850 nm and an overfilled launch (OFL), the optical core diameter for a fiber length in a range between 2 m and 300 m decreases by less than 5% and the numerical aperture decreases by less than 2.

Abstract: An optical fiber has a core region, a cladding region and at least one spacer layer disposed between the core region and the cladding region. The core region is positively doped and has a positive refractive index with respect to the glass matrix of the optical fiber. The cladding region is negatively doped and has a refractive index of at most zero with respect to the glass matrix. The numerical aperture of the optical fiber is composed of variable proportions of the positively doped core region and the negatively doped cladding region and results from the refractive indices of both regions.

Abstract: Methods for making a preform for a graded-index multimode fiber by using an inside deposition process are disclosed. The methods are characterized by an iterative refractive index profile correction with the following steps: determining a target refractive index profile for the preform to be produced, carrying out an inside deposition process with fixed volume flows for the reacting gases inside a tube and a given burner speed for all deposited layers, collapsing the tube and measuring the actual refractive index profile, comparing the target profile with the actual profile and calculating a correction value of index differences, converting this correction value in corrected burner speeds as varying process parameter, carrying out a inside deposition process with fixed gas flows and corrected burner speeds for all layers to be deposited.

Abstract: The invention relates to a bend insensitive gradient index multimode light conducting fiber comprising a leakage mode dependent optical core diameter that is uniform over its length and a numerical aperture that is uniform over its length, a core (1), an inner cladding (2), a refraction index trench (3) and an outer cladding (4), wherein the core (1) includes a core radius R1, an alpha-refraction index profile and a core refraction index difference dn1 with respect to the outer cladding (4), wherein the refraction index trench (3) includes a refraction index trench radius R3 and a trench refraction index difference dn3 with respect to the outer cladding (4), wherein the outer cladding (4) includes an outer cladding radius R4 and a refraction index between 1.40 and 1.55, wherein for a light wavelength of 850 nm and an overfilled launch (OFL), the optical core diameter for a fiber length in a range between 2 m and 300 m decreases by less than 5% and the numerical aperture decreases by less than 2.