What is claimed is:
1. An apparatus for compensating for optical loss, said apparatus comprising:
a plurality of optical fibers joined to define a plurality of output ports and a fiber junction; and
a signal amplification device positioned between the fiber junction and each of the plurality of output ports to communicate with said plurality of optical fibers.
2. The apparatus of claim 1 wherein said signal amplification device comprises a semiconductor optical amplifier.
3. The apparatus of claim 1 wherein said signal amplification device comprises a plurality of semiconductor optical amplifiers.
4. The apparatus of claim 1 further comprising an active fiber region including a dopant residing within said optical fibers between the fiber junction and each output port, and wherein said signal amplification device comprises at least one light source coupled to the active fiber region to emit light into the active fiber region at a wavelength and power sufficient to excite the dopant.
5. An apparatus for compensating for optical loss, said apparatus comprising:
a plurality of optical fibers joined to form an input port, a coupled region, a fiber junction, and a plurality of output ports; and
a signal amplification device positioned between the fiber junction and each of the plurality of output ports to communicate with said plurality of optical fibers such that an optical signal passing between the fiber junction and each of the output ports is amplified.
6. The apparatus of claim 5 wherein said signal amplification device comprises a semiconductor optical amplifier.
7. The apparatus of claim 5 wherein said signal amplification device comprises a plurality of semiconductor optical amplifiers.
8. The apparatus of claim 5 further comprising an active fiber region including a dopant residing within said optical fibers between the fiber junction and each output port, and wherein said signal amplification device comprises at least one light source coupled to the active fiber region to emit light into the active fiber region at a wavelength and power sufficient to excite the dopant.
9. The apparatus of claim 8 wherein one of said active fiber regions comprises erbium and wherein the other of said active fiber regions comprises a dopant other than erbium.
10. The apparatus of claim 8 wherein said at least one light source comprises a plurality of LEDs.
11. A method of compensating for optical loss, said method comprising the steps of:
receiving an optical signal through an input port of an optical splitter, said optical splitter comprising a fiber junction, a first output port, and a second output port;
dividing the optical signal at the fiber junction such that a first portion of the optical signal is directed toward the first output port and a second signal portion is directed toward the second output port; and
amplifying the first and second signal portions of the optical signal with a signal amplification device positioned between the fiber junction and each output port while the signal portions are traveling between the fiber junction and the output ports.
12. The method of claim 11 wherein said signal amplification device comprises a semiconductor optical amplifier and wherein said amplifying step includes the step of boosting the first and second signal portions via stimulated emission.
13. The method of claim 11 wherein said signal amplification device comprises a LED and wherein said optical splitter further comprises a dopant containing active fiber region between the fiber junction and each output port, said amplifying step comprising the step of emitting light from said LED into the active fiber region at a wavelength and power sufficient to excite the dopant as the first and second signal portions are passed through the active fiber regions.
14. A process of manufacturing an optical signal loss compensating device, said process comprising the steps of:
joining at least two optical fibers to form a coupled region, a fiber junction, and a plurality of output ports; and
positioning a signal amplification device between each output port and the fiber junction.
15. The process of claim 14 further comprising the step of radially splicing said at least two optical fibers between said fiber junction and said plurality of output ports prior to said positioning step.
16. The process of claim 15 wherein said signal amplification device comprises a semiconductor optical amplifier and wherein said positioning step comprises placing the semiconductor optical amplifier between the spliced ends of said at least two optical fibers.
17. A device made by the process of claim 14.
18. The process of claim 14 wherein said at least two optical fibers each comprise an active fiber region, and wherein said signal amplification device comprises a LED, said positioning step comprising the step of mounting the LED adjacent the active fiber region.
19. The process of claim 18 wherein said LED comprises a plurality of LEDs, said positioning step comprising the step of mounting said plurality of LEDs adjacent the active fiber region.
20. A loss compensating optical communication system comprising:
a transmitter;
a receiver;
a transmission line positioned between and cooperating with said transmitter and said receiver to carry an optical signal from said transmitter to said receiver; and
a loss compensating optical splitter communicating with said transmission line and comprising a plurality of optical fibers joined to define a fiber junction and a plurality of output ports, said splitter further including a signal amplification device positioned between the junction and each output port to provide a source of amplification to the optical signal carried through the plurality of fibers.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A force balance accelerometer comprising:
a housing;
a magnet producing a magnetic field within the housing;
a spring supporting a coil within the magnetic field, the coil having first and second terminals, with the first terminal connected to a common;
an operational amplifier having a first amplifier input, a second amplifier input, and an amplifier output, the first amplifier input being coupled to the second terminal of the coil and a first feedback path, and the second amplifier input being coupled to a reference impedance and a second feedback path, the reference impedance having a reactive component of impedance.
2. The force balance accelerometer of claim 1 wherein the coil has a complex impedance of a direct current resistance plus a reactance, and the reactive component of the reference impedance substantially matches the reactance of the complex impedance of the coil.
3. The force balance accelerometer of claim 2 wherein the reference impedance has a resistive component substantially matching the direct current resistance of the coil.
4. The force balance accelerometer of claim 3 wherein the reference impedance comprises a second coil.
5. The force balance accelerometer of claim 4 wherein the second coil has a temperature coefficient of impedance substantially equivalent to that of the coil.
6. The force balance accelerometer of claim 3 wherein the reference impedance comprises a second coil and a resistor.
7. The force balance accelerometer of claim 3 wherein the first feedback path includes a first resistor, the second feedback path includes a second resistor, and the first and second resistor have substantially equivalent resistances.
8. The force balance accelerometer of claim 7 wherein the first feedback path and the second feedback path each have an associated transfer function, the magnitudes of which are less than unity over a predefined bandwidth of frequencies.
9. The force balance accelerometer of claim 8 wherein the resistances of the first and second resistors are substantially greater than the impedances of the coil and the reference impedance over the predefined bandwidth of frequencies.
10. A force balance accelerometer comprising:
a single coil geophone having two terminals;
a force actuator coupled to at least one of the two terminals, the force actuator having a single amplifier stage and including a reference impedance comprising a reference coil having a reactive component coupled to the single amplifier stage.
11. The force balance accelerometer of claim 10 wherein the reference impedance comprises the reference coil and a reference resistor.
12. The force balance accelerometer of claim 11 wherein the reference coil and the reference resistor are connected in series.
13. The force balance accelerometer of claim 12 wherein the reference coil and the reference resistor have substantially similar variations in impedance with temperature.
14. A force balance accelerometer comprising:
a housing;
means for providing a magnetic field in the housing;
a coil movably supported in the magnetic field;
means for generating a current coupled to the coil, the means for generating a current including means for comparing a reference voltage generated across a reference impedance to a voltage generated across the coil, the reference impedance including a reference coil having a reactive component.