Distributed feedback ring laser

Details Distributed feedback ring laser Distributed feedback ring laser

1998-08-24

2001-08-07

Bovernick, Rodney (Department: 2874)

Coherent light generators

Particular resonant cavity

Folded cavity

C372S006000, C372S019000, C372S096000

Reexamination Certificate

active

06272165

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a single frequency laser arrangement and, in particular, to a single longitudinal mode narrow linewidth and low threshold all fibre laser arrangement.
BACKGROUND OF THE INVENTION
Single frequency lasers are particularly useful in optical communication systems, fibre sensors, and spectroscopy as narrow linewidth sources. There has been increasing interest in developing single longitudinal mode fibre lasers.
One approach to obtain single longitudinal mode operation is to use a distributed feedback structure (DFB). As an example, reference is made to H Kogelnik and C V Shank, “Coupled-wave theory of distributed feedback lasers”, Journal of Applied Physics vol. 43, no. 5, pp. 2327-2335, 1972. Recently, DFB fibre lasers have been demonstrated, using in fibre gratings directly written into rare earth doped fibres [J. T. Kringlebotn, J-L Archambault, L. Reekie, and D. N. Payne, “Er
3+
:Yb
3+
-codoped fibre distributed-feedback laser”, Optics Letters., vol. 19, no. 24, pp. 2101-2103, 1994 and A. Asseh, H. Storoy, J. T. Kringlebotn, W. Margulis, B. Sahlgren, S. Sandgren, R. Stubbe, and G. Edwall, “10 cm Yb
3+
DFB fibre laser with permanent phase shifted grating”, Electron. Letters., vol. 31, no. 12, pp. 969-970, 1995]. Using fibre DFB structures permits all fibre devices and wavelength selectivity over a wide range. However, the use of short pieces of heavily doped fibre has a disadvantage of low slope efficiency and large linewidth. Another approach to obtain single longitudinal mode operation is to use the travelling wave operation of ring fibre lasers [G. J. Cowle, D. N. Payne, and D. Reid, “Single-frequency travelling-wave erbium-doped fibre loop laser”, Electron. Letters., vol. 27, no. 3, pp. 229-230, 1991]. Long cavity lengths of ring lasers provide narrow linewidth operation. However, single longitudinal mode operation of ring lasers reported to date has been achieved mostly with pigtailed non-fibre intracavity elements.
Suppression of spatial hole burning by internal modulation of the laser cavity [T. Stolte and R. Ulrich, “Er-fibre lasers: suppression of spatial hole burning by internal modulation”, Electron. Lett., vol. 29, no. 19, pp. 1686-1688, 1993] can be used to ensure single longitudinal mode operation. However, it also requires pigtailed non-fibre intracavity elements.
Further, single longitudinal mode narrow linewidth operation can be achieved using injection locking [J. D. C. Jones and P. Urquhart, “An injection-locked erbium fibre laser”, Optical Communications., vol. 76 no. 1, pp. 42-46, 1990]. However, this approach requires an external single longitudinal mode narrow linewidth laser.
The disadvantage of using a coupled cavity fibre laser incorporating fibre Bragg gratings [S. V. Chernikov, J. R. Taylor, and R. Kashyap, “Coupled-cavity erbium fibre lasers incorporating fibre grating reflectors”, Opt. Letters., vol. 18, no. 23, pp. 2023-2025, 1993] or Fox-Smith fibre lasers [P. Barnsley, P. Urquhart, C. Millar, and M. Brierley, “Fiber Fox-Smith resonators: application to single-longitudinal-mode operation of fibre lasers”, Journal of the Optical Society of America vol. 5, no. 8, pp. 1339-1346, 1988] is that these approaches require several perfectly matched gratings, although the approaches permit all fibre devices.
A saturable absorber [M. Horowitz, R. Daisy, B. Fischer, and J. Zyskind, “Narrow-linewidth, singlemode erbium-doped fibre laser with intracavity wave mixing in saturable absorber”, Electron. Letters., vol. 30, no. 8, pp. 648-649, 1994] can be used to achieve single longitudinal mode narrow linewidth operation. However, the absorber increases the lasing threshold and reduces slope efficiency of the laser.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved laser arrangement which overcomes some of the disadvantages of the aforementioned laser arrangements.
In accordance with the first aspect of the present invention there is provided a laser arrangement which comprises a ring cavity with a gain portion, an input-output coupling connected to the ring cavity, a grating interposed in the gain portion of the ring cavity, and a pumping means connected to the gain portion of the ring cavity and the grating, such that, upon activation of the pumping means, the laser arrangement operates as a laser and produces an output at said input-output coupling.
Preferably, the ring cavity and grating are formed from the one piece of rare earth doped optical fibre with the grating being written directly into the optical fibre.
Preferably, the laser arrangement acts as a distributed feedback structure for obtaining a single longitudinal mode of operation over a frequency linewidth of less than 70 kHz.
In broad terms, the preferred embodiment of the present invention provides a single longitudinal mode narrow linewidth and low threshold laser, comprising a distributed feedback structure inserted into a ring cavity.
More specifically, the preferred embodiment of the present invention provides a single longitudinal mode narrow linewidth and low threshold laser arrangement, comprising a distributed feedback structure for obtaining single longitudinal mode operation, and an output coupler to provide output coupling and additional feedback through the ring cavity. The additional feedback of the lasing signal via the ring cavity decreases the lasing threshold because of the reduction in effective resonator losses. The additional feedback also leads to laser linewidth narrowing provided by self injection of the lasing signal through the ring cavity which can be considered as an extended cavity.
In a preferred embodiment the distributed feedback structure is a grating written into an Er
3+
:Yb
3+
-doped phosphosilicate fibre with a transmission peak within the corresponding photonic bandgap. Splicing of this structure within a ring cavity has resulted in a single longitudinal mode operation at the transmission peak wavelength. Such an arrangement has advantages in producing single longitudinal mode narrow linewidth and low threshold laser sources in optical communication systems, fibre sensors, and spectroscopy.


REFERENCES:
patent: 3772611 (1973-11-01), Smith
patent: 4955028 (1990-09-01), Alferness et al.
patent: 5052015 (1991-09-01), Ackerman et al.
patent: 5052016 (1991-09-01), Mahbobzadeh et al.
patent: 5159601 (1992-10-01), Huber
patent: 5243609 (1993-09-01), Huber
patent: 5305336 (1994-04-01), Adar et al.
patent: 5347533 (1994-09-01), Higashi et al.
patent: 5379318 (1995-01-01), Weber
patent: 5841799 (1998-11-01), Hiroki
patent: 59172286 (1984-09-01), None
patent: 63-164382 (1988-07-01), None
patent: 40-4132284A (1992-05-01), None
patent: 4-349682 (1992-12-01), None
patent: 40-5259538A (1993-10-01), None
patent: WO87/01246A (1987-02-01), None
patent: WO95/25367 (1995-09-01), None
Cheng, Y. et al.; Optics Letters, vol. 20, No. 8; Apr. 1995; pp. 875-877, “Stable single-frequency traveling-wave fiber loop laser with integral saturable-absorber-based tracking narrow-band filter”.
Guy, M., et al.; Electronics Letters, vol. 31, No. 22; Oct. 1995; pp. 1924-1925, Single-frequency erbium fibre ring laser with intercavity phase-shifted fiber Bragg gating narrowband filter.
Chao-Xiang Shi, et al.; Journal of Lightwave Technology, vol. 13, No. 9; Sep. 1995; pp. 1853-1857, “Bias of a resonator fiber optic gyro composed of a polarization-maintaining fiber ring resonator with a photoinduced birefringent grating”.
Stepanov, D., et al.; Australian conference on optical fibre technology; Dec. 1995; pp. 413-416, “Ring distributed-feedback fibre laser”.
Supplementary European search report dated Nov. 1998.
International search report dated Feb. 24, 1997.

Affiliated with

Also associated with

Rating

Distributed feedback ring laser does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Distributed feedback ring laser, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Distributed feedback ring laser will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2438341