Optical frequency and temperature sensor system

Details Optical frequency and temperature sensor system Optical frequency and temperature sensor system

1997-07-18

2001-06-05

Sanghavi, Hemang (Department: 2874)

Optical waveguides

Optical waveguide sensor

C372S032000, C372S094000, C356S329000

Reexamination Certificate

active

06243506

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to an optical frequency and temperature sensor and its applications. Especially, this invention uses more than one set of optical resonators with fibers having different thermal expansion factors and refractive indices which can be used to detect the temperature and optical frequency simultaneously in order to be used for designing a highly stabilized frequency for light source of laser system.
CROSS-REFERENCE TO RELATED APPLICATION
The optical fiber sensor has been wildely used for temperature detection and frequency stabilization for the following reasons: light weight, high temperature sensitivity and compatible to all fiber systems. Especially frequency division multiplexing communication systems require higher channel density. Maintaining a tunable frequency and stabilized light source is very important.
In the area of research & development on frequency stabilization for laser system, articles issued by S. Sudo et al in 1989 in IEEE PHOTONICS TECHNOLOGY LETTERS, Vol. I, 10th Issue, PP281-284 and by M. Tetu et al in the same year in JOURNAL OF LIGHTWAVE TECHNOLOGY, Vol. 7, 10th Issue, PP 1540-1547, proposed that the feed-back control can be carried out with molecule to absorb the spectrum or with atom resonance frequency spectrum to serve as reference for an absolute stabilized frequency. However, both atom and molecule are difficult to purify and pack, the frequency band has lower tunability and installations for such a usage could be very expensive. Therefore, these proposals are not wildely applied to communication systems. Until in 1994, E. T. Peng et al suggested in their article in IEEE PHOTONICS TECHNOLOGY LATTERS to use a delicate thermostat in the present single optical fiber resonator frequency control device to control the temperature to 0.01° C., or as suggested by U.S. Pat. No. 4,896,327 issue to A. Ebberg in 1990 to use a temperature complementary device to stabilize the temperature for optical fiber resonator. Obviously, all these proposals are limited to have the detection to be made on frequency of light source only when a highly stabilized temperature is able to be maintained. Since the frequency and temperature are interrelated to each other and any change happened to one which would cause a variation to the other. Therefore, these methods of keeping a stabilized temperature is not very reliable which will lead the system to be less delicate and having lower sensibility.
BRIEF SUMMARY OF THE INVENTION
In view of the above, the invention proposed a temperature and optical frequency sensor using two different optical fiber resonators. The fiber with different thermal expansion factor and refractive index can be used to sense the temperature variation. The optical resonators with different cavity lengths can be used to detect the frequency deviation. Applying a laser, a micro-processor and two optical resonators with different thermal expansion factors and resonate lengths, the device which can detect the temperature and frequency simultaneously. Furthermore, this device can provide tunable and highly stabilized light source for optical system application.
Instead of using a delicate thermostat to control the temperature to 0.01° C., or using temperature complementary device to stabilize temperature, this invention applied in its sensor system with more than one set of different optical fiber resonators. Data obtained from this arrangement is to serve for the detection of frequency of light source and of temperature according to digital data mapping in microprocessor system. This system shall be able to detect frequency and temperature simultaneously and to provide a tunable and stabilized light source for optical fiber communication system through a feed-back mechanism.
One important object of this invention is to provide a sensor system with a feed-back mechanism for stabilizing the optical frequency without highly accurate temperature control.
Moreover, another object of this invention is to provide a sensor system which has a high sensitivity for temperature sensing without frequency stabilization.
One advantage of this invention is to provide a sensor system which does not have to raise its SNR of characteristic curve of fiber ring resonator by modulation, instead, using the method of subtraction between respective characteristic curves of the fiber resonators to obtain higher SNR for a part of its frequency band.


REFERENCES:
patent: 4368981 (1983-01-01), Ozeki
patent: 4632551 (1986-12-01), Pavlath
patent: 4896327 (1990-01-01), Ebberg

Affiliated with

Also associated with

Rating

Optical frequency and temperature sensor system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Optical frequency and temperature sensor system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical frequency and temperature sensor system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2524937