Multimode optical fibers
AssigneeDraka Comteq B.V.
InventorsAsghar Gholami, Denis Molin, Pierre Sillard, Yves Lumineau
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Abstract
A multimode optical fiber has an equivalent modal dispersion value (DMDinner&outer) of less than 0.11 ps/m for (Δλmax×D)>0.07 ps/m as measured on a modified DMD graph. The modified DMD graph accounts for chromatic dispersion to ensure that the multimode optical fiber has a calculated effective bandwidth EBc greater than 6000 MHz-km when used with multimode transverse sources.
Claims15
A multimode optical fiber, wherein the multimode fiber possesses a refractive index profile such that a measurement of the dispersion modal delay (DMD), the DMD graph of which has been modified by adding a delay (Δttrace) to each trace:
- Δ
-
-
- t
- trace
- =
- Δ
-
-
- λ
- max
- ×
- D
- ×
- L
-
- (
- r
- trace
- a
- )
- β
- where rtrace is the center position of the injection of the light pulse corresponding to the trace,
- a is the core radius of the multimode optical fiber,
- L is the length of the multimode optical fiber,
- D is the chromatic dispersion of the multimode fiber at the wavelength of the light pulse,
- β is the coefficient of the delay, and
- Δλmax is the maximum spectral width of a source intended to be used with the fiber,
- gives an equivalent modal dispersion value (DMDinner&outer), measured at a quarter of the height of the leading edge of the first trace and at a quarter of the height of the trailing edge of the last trace, of less than 0.11 ps/m for (Δλmax×D)>0.07 ps/m.
A multimode optical fiber having a graded-index profile, wherein:
- the multimode optical fiber has a calculated effective bandwidth (EBc) greater than 6000 MHz-km;
- at wavelengths between 840 nanometers and 860 nanometers, the multimode optical fiber has a chromatic dispersion between −80 ps/(nm·km) and −120 ps/(nm·km);
- and
- the multimode optical fiber has an equivalent modal dispersion value (DMDinner&outer) of less than 0.11 ps/m for (Δλmax×D)>0.07 ps/m as measured on a DMD graph;
- wherein the DMD graph is modified by adding a delay (Δttrace) to each trace:
- Δ
-
-
- t
- trace
- =
- Δ
-
-
- λ
- max
- ×
- D
- ×
- L
-
- (
- r
- trace
- a
- )
- β
- wherein,
- rtrace is the center position of the injection of the light pulse corresponding to the trace,
- a is the core radius of the multimode optical fiber,
- L is the length of the multimode optical fiber,
- D is the chromatic dispersion of the multimode fiber at the wavelength of the light pulse,
- β is the coefficient of the delay, β being greater than or equal to 1, and
- Δλmax is the maximum spectral width of a source intended to be used with the fiber;
- and
- wherein the equivalent modal dispersion value (DMDinner&outer) is measured on the modified DMD graph at a quarter of the height of the leading edge of the first trace and at a quarter of the height of the trailing edge of the last trace.
A method for selecting multimode optical fibers, comprising:
- manufacturing multimode optical fibers, each multimode optical fiber having a graded-index profile of a given value of parameter α;
- measuring the dispersion modal delay on a DMD graph plotted for each multimode optical fiber, wherein the modal dispersion (DMDinner&outer) is measured at a quarter of the height of the leading edge of the first trace and at a quarter of the height of the trailing edge of the last trace;
- modifying the DMD graph of each fiber by adding a delay (Δttrace) to each trace:
- Δ
-
-
- t
- trace
- =
- Δ
-
-
- λ
- max
- ×
- D
- ×
- L
-
- (
- r
- trace
- a
- )
- β
- where rtrace is the center position of the injection of the light pulse corresponding to the trace,
- a is the core radius of the multimode optical fiber,
- D is the chromatic dispersion of the multimode optical fiber at the wavelength of the light pulse, and
- Δλmax is the maximum spectral width of a source intended to be used with the multimode optical fiber;
- and
- selecting those multimode optical fibers having an equivalent modal dispersion value of less than 0.11 ps/m as measured on the modified DMD graph.
Dependencies are inferred from the claim text.