Optical fibre amplifier and laser
| Title: | Optical fibre amplifier and laser |
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| Patent Number: | 5,406,410 |
| Publication Date: | April 11, 1995 |
| Appl. No: | 08/054,969 |
| Application Filed: | May 03, 1993 |
| Abstract: | An optical fibre amplifier comprises a thulium-doped optical fibre pumped at 790 nm by a semi-conductor diode laser coupled to the fibre via optical fibre coupler. The amplifier is optically coupled in series to a pair of systems fibres to provide amplification to optical signals. |
| Inventors: | Hanna, David C. (Southampton, GB2); Carter, Jeremy N. (Kent, GB2); Tropper, Anne C. (Hants, GB2); Smart, Richard G. (Hants, GB2) |
| Assignees: | British Telecommunications plc (London, GB2) |
| Claim: | We claim |
| Claim: | 1. An optical amplifier for amplifying input light signals, said amplifier comprising |
| Claim: | a fluorozirconate optical fibre having its core doped with Tm.sup.3+, and |
| Claim: | pump means for providing optical pump power to said fibre to raise Tm.sup.3+ ions therein directly to the upper Stark levels of the .sup.3 F.sub.4 level. |
| Claim: | 2. An optical amplifier as in claim 1, in which the pump means includes a diode laser. |
| Claim: | 3. An optical amplifier as in claim 2, in which the diode laser is an AlGaAs laser. |
| Claim: | 4. An optical amplifier as in claim 1 in which the material of the optical fibre produces a non-radiative, multiphonon decay rate out of the .sup.3 F.sub.4 level that is negligible compared to the radiative rate. |
| Claim: | 5. An optical amplifier as in claim 4, in which the optical fibre material comprises a ZBLANP composition. |
| Claim: | 6. An optical amplifier as in claim 1 in which the optical fibre is doped with about 1000 ppm weight of Tm.sup.3+. |
| Claim: | 7. A laser comprising |
| Claim: | a resonant cavity defined by reflection means and configured to resonate at the wavelength of the .sup.3 F.sub.4 -.sup.3 H.sub.6 transition, and |
| Claim: | an optical amplifier within the resonant cavity, the optical amplifier including a fluorozirconate optical fibre having its core doped with Tm.sup.3+ and pump means for providing optical pump power to said fibre to raise Tm.sup.3+ ions therein directly to the upper Stark levels of the .sup.3 F.sub.4 level. |
| Claim: | 8. A laser as in claim 7, in which the reflection means comprise a pair of dielectric mirrors. |
| Claim: | 9. A laser as in claim 8, in which one of the mirrors has a reflectivity greater than 99% for wavelengths greater than 805 nm. |
| Claim: | 10. A laser as in claim 9, in which said one mirror has a steep transmission edge between 790 nm and 800 nm in air. |
| Claim: | 11. A laser as in claim 9, in which both mirrors have a reflectivity greater than 99% for wavelengths greater than 805 nm and a steep transmission edge between 790 nm and 800 nm in air. |
| Claim: | 12. A laser as in claim 11, in which the optical pump power is at 777 nm. |
| Claim: | 13. A laser as in claim 10, and in which the other mirror has a reflectivity in air of about 90%, 30% and 95% at 777 nm, 805 nm and 820 nm respectively. |
| Claim: | 14. An optical communication system comprising an optical fibre communications network having an optical signal transmission fibre optically coupled into an optical amplifier for amplifying optical signals from the transmission fibre, said optical amplifier including a fluorozirconate optical fibre having its core doped with Tm.sup.3+ and pump means for providing optical pump power to said fibre to raise Tm.sup.3+ ions therein directly to the upper Stark levels of the .sup.3 F.sub.4 level. |
| Claim: | 15. An optical communication system comprising |
| Claim: | an optical fibre communications network having an optical signal transmission fibre optically coupled to receive optical signals emanating from a laser; |
| Claim: | said laser including a fluorozirconate optical fibre having its core doped with Tm.sup.3+ and pump means for providing optical pump power to said fibre to raise Tm.sup.3+ ions therein directly to the upper Stark levels of the .sup.3 F.sub.4 level, said doped fibre being disposed within a resonant cavity defined by reflection means and configured to resonate at the wavelength of the .sup.3 F.sub.4 -.sup.3 H.sub.6 transition. |
| Current U.S. Class: | 359/341; 372/6; 372/40; 372/70; 359/109 |
| Current International Class: | H01S 306; H01S 3094 |
| Patent References Cited: | 4965803 October 1990 Esterowitz et al. 4967416 October 1990 Esterowitz et al. 4969150 November 1990 Esterowitz et al. 4969154 November 1990 Esterowitz et al. |
| Other References: | France et al, "Progress in Fluoride Fibres for Optical Communications", BT Telecom Technol J., vol. 5, No. 2, Apr. 1987. Allain et al, Electron. Lett., vol. 25, #24, pp. 1660-1662, Nov. 23, 1989. Allen et al, Appl. Phys. Lett., vol. 55, #8, pp. 721-722, Aug. 21, 1989. Esterowitz et al, Electron. Lett., vol. 24, #17, p. 1104, Aug. 18, 1988; abst. only provided herewith. Hanna et al, Electron. Lett., vol. 24, #19, pp. 1222-1223, Sep. 15, 1988; Abst. only provided herewith. "Continuous-Wave Oscillation of a Monomode Thulium-Doped Fibre Laser", Electronics Letters, 15th Sep. 1988, vol. 24, No. 19, pp. 1222-1223. "Tunable CW Lasing Around 0.82, 1.48, 1.88 and 2.35 .mu.m In Thulium-Doped Fluorozirconate Fibre", Electronics Letters, 25 (Nov. 23, 1989) vol. 25, No. 24, pp. 1660-1662. "CW Diode-Pumped Operation of 1.97.mu.m Thulium-Doped Flurozirconate Fibre Laser", Electronics Letters, 26th Apr. 1990, vol. 26, No. 9, pp. 599-601. Allen et al, "CW Diode Pumped 2.3.mu.m Fiber Laser", Applied Physics Letters, 55 (1989) Aug. 21, No. 8, New York, U.S., pp. 721-722. Guery et al, "Optical Properties of TM.sup.3+ Ions in Indium-Based Fluoride Glasses", Journal of Luminescence, 42(1988) pp. 181-188. Millar et al., "Efficient Up-Conversion Pumping At 800nm of an Erbium-Doped Fluoride Fibre Laser Operating at 850nm", Electronics Letters, Oct. 25, 1990, vol. 26, No. 22, pp. 1871-1873. Davey et al, SPIE 1581, Fiber Loses Lovaces and Amplifiers III, 1991. Davey et al, Br. Telecom. J., (UK), vol. 7, #1, pp. 58-68; Jan. 1989. |
| Primary Examiner: | Moskowitz, Nelson |
| Attorney, Agent or Firm: | Nixon & Vanderhye |
| Accession Number: | edspgr.05406410 |
| Database: | USPTO Patent Grants |
| Language: | English |
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