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US 6,496,634 B1Granted
Holey fibers filled with raman active fluid
OwnerMarc David Levensoninventor
Life of this patent
Estimating the term…
Abstract
Hollow core or “holey” optical fibers are filled with a gas or liquid which exhibits high Raman gain. Such gases as hydrogen and hydrogen isotopes are preferred embodiment. When these fibers are pumped with a pump laser, signals at an appropriate frequency carried by the fiber may be amplified, attenuated, changed to a different frequency, or mixed with other signals.
Claims34
An apparatus, comprising:
- a Raman amplifying gas filled optical fiber, the Raman amplifying gas filled optical fiber having an axis, the Raman amplifying gas filled optical fiber comprising a core region and a cladding region surrounding the core region, the Raman amplifying gas filled optical fiber containing one or more holes, the holes filled with a Raman active gas, wherein the density of holes and the density of gas within the holes is sufficient so that light having a first frequency f1 propagating within the core region of the Raman amplifying gas filled optical fiber is amplified when the fiber is pumped with a pump laser having a second frequency f2 differing from the first frequency f1 by a Raman shift fR corresponding to the Raman active gas.
An apparatus, comprising:
- a Raman amplifying gas filled optical fiber, the Raman amplifying gas filled optical fiber having an axis, the Raman amplifying gas filled optical fiber comprising a core region and a cladding region surrounding the core region, the Raman amplifying gas filled optical fiber containing holes, the holes filled with a Raman active gas, the Raman active gas containing a hydrogen isotope, wherein the density of holes and the density of gas within the holes is sufficient so that light having a first frequency propagating within the core region of the Raman amplifying gas filled optical fiber is amplified when the fiber is pumped with a pump laser having a second frequency differing from the first frequency by a Raman shift corresponding to the Raman active gas.
A system, comprising:
- a Raman amplifying gas filled optical fiber, the Raman amplifying gas filled optical fiber having an axis, the Raman amplifying gas filled optical fiber comprising a core region and a cladding region surrounding the core region, the Raman amplifying gas filled optical fiber containing holes, the holes filled with a Raman active gas, wherein the density of holes and the density of gas within the holes is sufficient so that light having a first frequency propagating within the core region of the Raman amplifying gas filled optical fiber is amplified when the fiber is pumped with a pump laser having a second frequency differing from the first frequency by a Raman shift corresponding to the Raman active gas;
- a laser for producing light of the second frequency;
- optical means for introducing light from the laser into the Raman amplifying gas filled optical fiber;
- and
- optical means for introducing light of the first frequency into the Raman amplifying gas filled optical fiber.
2 more elements
A method of controlling light of a particular frequency band having a frequency f1 in an optical communication system comprising the steps of:
- (a) providing a length of optical fiber having a core region and a cladding region, the optical fiber it containing voids filled with gas the voids positioned along the fiber such that the electric field amplitude of the light of frequency f1 guided by the core region penetrates at least some of the void regions to a substantial extent, wherein the gas has at least one Raman active vibrational, rotational or vibronic transition having a particular Raman frequency shift fR;
- (b) providing pump radiation with a nominal frequency fP differing from f1 by the amount of the Raman frequency shift fR, the pump radiation having a pump spectrum tailored to transfer power between the radiation at frequency fP and f1 by stimulated Raman gain with a desired profile over the particular frequency band, the pump radiation having power sufficient to transfer substantial power between the radiation at frequency fP and f1 over the length of optical fiber;
- (c) providing a means to couple the light of frequency f1 into and out of the length of optical fiber;
- (d) providing a means to couple the pump radiation into the length of optical fiber;
- whereby the light of frequency f1 input into the fiber is controlled with a profile determined by a convolution of the pump radiation spectrum and Raman gain spectrum of the gas.
2 more elements
A method of controlling light of a particular frequency band having a frequency f1 in an optical communication system comprising the steps of:
- (a) providing pump radiation of frequencies f4 and f3;
- (b) providing a length of optical fiber having a core region and a cla containing voids filled with a Raman active gas, the voids positioned along the fiber such that the electric field amplitude of the light of frequency f1 guided by the core region penetrates at least some of the void regions to a substantial extent, wherein the gas has a substantial non linear index of refraction, wherein the pump radiation has power sufficient to transfer substantial power between the radiation at frequencies f1 and f2=f4−f3+f1 over the length of optical fiber, and wherein phase velocities in the optical fiber of waves having frequencies f1, f3, f4 and f2 are such that the coherence length for the four wave mixing process that produces a non linear polarization in the gas at the frequency f2 is greater than one half the fiber length;
- (c) providing a means to couple the light of frequency f1 into the length of optical fiber;
- and
- (d) providing a means to couple, the pump radiation into the length of optical fiber.
2 more elements
Dependencies are inferred from the claim text.