Stability compensated broadband source and fiber interferometer
First Claim
1. A broadband light source having an emission spectrum, said emission spectrum being characterized by a mean wavelength, said source comprising an active medium which is pumped at a pump wavelength by a pump source to cause said active medium to emit radiation, said pump source having a pump power and a pump wavelength which substantially minimize the sum of the intrinsic temperature dependence of the active medium, the pump power dependence of the mean wavelength and the pump wavelength dependence of the mean wavelength, said sum being defined as:
- ##EQU11## wherein <
λ
>
is the means wavelength of the signal;
T is the temperature;
P is the pump power of the pump source; and
λ
p is the wavelength of the light emitted by the pump source.
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Abstract
The present invention discloses a thermally stable rare-earth doped fiber source comprising an active medium such as Erbium or Neodymium. The thermal stability of the mean wavelength of such a source is determined by three contributions as expressed by the following differential equation: ##EQU1## The first term is the intrinsic temperature dependence of the active medium, the second term is the pump power dependence and the third term is a contribution that arises from the dependence of the emission wavelength on the pump wavelength. The method of the present invention minimizes the temperature dependence on the mean wavelength by using the above equation and optimizing the values of the pump power and the pump wavelength so that the three contributions in the governing equation cancel each other.
49 Citations
42 Claims
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1. A broadband light source having an emission spectrum, said emission spectrum being characterized by a mean wavelength, said source comprising an active medium which is pumped at a pump wavelength by a pump source to cause said active medium to emit radiation, said pump source having a pump power and a pump wavelength which substantially minimize the sum of the intrinsic temperature dependence of the active medium, the pump power dependence of the mean wavelength and the pump wavelength dependence of the mean wavelength, said sum being defined as:
- ##EQU11## wherein <
λ
>
is the means wavelength of the signal;T is the temperature; P is the pump power of the pump source; and λ
p is the wavelength of the light emitted by the pump source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
- ##EQU11## wherein <
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25. An optical sensor for sensing an ambient effect comprising:
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a loop comprising an optical fiber having two polarization modes; and a broadband light source for introducing light into said loop, said source having an active medium which emits radiation in an emission spectrum in response to application of pump energy to said active medium, said active medium being pumped at a pump wavelength by a pump source to cause said active medium to emit radiation, said pump source having a pump power and a pump wavelength which substantially minimize the sum of the intrinsic temperature dependence of the active medium, the pump power dependence of the mean wavelength and the pump wavelength dependence of the mean wavelength, said sum being defined as;
##EQU12## wherein <
λ
s >
is the means wavelength of the signal;T is the temperature; P is the pump power of the pump source; and λ
p is the wavelength of the light emitted by the pump source. - View Dependent Claims (26)
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27. An apparatus, comprising:
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an interferometer; a pump light source that emits pump light and a broadband light source having an emission spectrum, said emission spectrum being characterized by a mean wavelength, said source comprising an active medium, said active medium being pumped at a pump wavelength by said pump source to cause said active medium to emit radiation, said pump source having a pump power and a pump wavelength which substantially minimize the sum of the intrinsic temperature dependence of the active medium, the pump power dependence of the means wavelength and the pump wavelength dependence of the mean wavelength, said sum being defined as;
##EQU13## wherein <
λ
s >
is the mean wavelength of the signal;T is the temperature; P is the pump power of the pump source; and λ
p is the wavelength of the light emitted by the pump source. - View Dependent Claims (28, 29, 30)
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31. A method for stabilizing the temperature dependence of a broadband source comprising an active medium and having an emission spectrum, comprising the steps of:
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pumping an active medium by means of a pump source at a pump wavelength to cause said active medium to emit radiation, said emission spectrum being characterized by a mean wavelength; and selecting the pump power and the pump wavelength of said pump source so as to minimize the total variation of the mean wavelength with respect to temperature, said pump power and said pump wavelength minimizing the sum of the intrinsic temperature dependence of the active medium, the pump power dependence of the mean wavelength and the pump wavelength dependence of the mean wavelength, said sum being defined as;
##EQU14## wherein <
λ
s >
is the mean wavelength of the signal;T is the temperature; P is the pump power of the pump source; and λ
p is the wavelength of the light emitted by the pump source. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification