CN1545171A - Single-double wave convertible wavelength location and interval adjustable erbium doped fibre-optical laser - Google Patents

Abstract

The invention relates to a double-wavelength Erbium-doped optical fiber laser, especially a convertible single double-wavelength, regulable wavelength position and space, stable output laser, including reflector, pumping laser, wavelength division multiplexing optical coupler, Erbium-doped optical fiber, polarization controller, etc. It utilizes elastic optical effect to cause stress double refraction in optical fiber, to make two reflecting films with orthogonal polarizing directions of Prague grating separated from each other in wavelength, utilizes polarization hole burning effect to overcome mode competition caused by Erbium-doped optical fiber uniform gain widening, implementing double-wavelength stable output at normal temperature, by changing magnitude of force applied on axial and side directions, respectively controls and tunes position and space of two wavelengths. By adjusting polarization controller, it changes in-cavity polarizing state to implement switching between single double wavelengths. It has simple structure, convenient adjustment, low cost and stable working at normal temperature.

Description

Single-double wave switchable wavelength position and adjustable at interval erbium doped fiber laser

Technical field

The present invention relates to a kind of dual wavelength erbium doped fiber laser, particularly can realize the wavelength location of convertible between the single-double wave, two laser output and wavelength interval adjustable with can at room temperature stablize the laser of exporting.

Background technology

Multiwavelength Erbium-doped Fiber Laser has purposes widely in optical communication and light sensory field, and for example in dense wavelength division multiplexing system, in many reference amounts Fibre Optical Sensor and the optical soliton source, this kind light source all is extremely important.But since the mode competition that the gain broadening effect in the Er-doped fiber causes, the difficult multi-wavelength output that realizes under the normal temperature in a laser cavity.Will realize multi-wavelength output at present, generally adopt following method to realize: a kind of method is Er-doped fiber to be put into cool off in the liquid nitrogen with minimizing gain broadening, but this method is obviously impracticable.Another kind method is that a plurality of fiber laser wavelength division multiplexing are coupled, though it can at room temperature obtain stable multi-wavelength output, needs with devices such as a plurality of drive circuits and laser cavities.Also having a kind of method is to insert the method for frequency shifter in the chamber, and shortcoming is to cost an arm and a leg.

Summary of the invention

The present invention applies lateral stress and axial stress in a Bragg fiber grating simultaneously by a kind of stress adjusting bracket, applying lateral stress can make the reflection mould of two polarization direction quadratures of common Bragg fiber grating separate on wavelength, utilize polarisation hole-burning effect to overcome the mode competition that Er-doped fiber uniform gain broadening causes, realize dual wavelength output stable under the normal temperature.Put on the accurate respectively control of big I of lateral stress and axial stress and the wavelength interval and the wavelength location of tuning two wavelength by change.For each lateral stress and axial stress, can realize single wavelength of fiber laser and the switch transition between the dual wavelength output by the Polarization Controller of adjusting in the laser cavity again.Result for retrieval shows still there is not a kind of dual wavelength erbium doped fiber laser that adopts structure of the present invention at present.The present invention-single-double wave is convertible, the adjustable erbium doped fiber laser of wavelength location and interval, it comprises: pump laser, pumping/signal Wavelength division multiplexing optical coupler, Er-doped fiber, Polarization Controller etc., be characterized in: the port a of Wavelength division multiplexing optical coupler 2 is connected with the output of pump laser 1, port b is connected with reflector 5, port c is connected with an end of Er-doped fiber 3, and the other end of Er-doped fiber 3 is connected with Polarization Controller 4; The other end of Polarization Controller 4 is connected with Fiber Bragg Grating mechanism 6, and the other end of Fiber Bragg Grating mechanism is connected with optical isolator 7, and laser is exported from the optical isolator other end; Tunable fiber Bragg grating mechanism 6 is made of Fiber Bragg Grating 8, support optical fiber 9, axial stress mechanical tuning device 10 and lateral stress mechanical tuning device 11, Bragg grating 8 is middle with support optical fiber 9 parallel two fixed flat planars 15 that are put in, fixed flat planar 15 links to each other with lateral displacement stepping mechanism 16, tail optical fiber one end of Bragg grating 8 is fixed by stiff end 12, the tail optical fiber other end links to each other with stepping mechanism 14, carries out the stretching fine tuning of displacement (amount of deflection) by the differential thread adjuster; Axial stress mechanical tuning device 10 is made of stiff end 12, guide rail 13 and displacement (amount of deflection) stepping mechanism 14; Lateral stress mechanical tuning device 11 is made of two fixed flat planars 15 and lateral displacement stepping mechanism 16.Reflector can be various broadbands or narrow band fiber or non-fiber reflection device, optical fiber and the non-fiber reflection devices such as Sagnac ring formed as the Bragg fiber grating in uniform period or non-homogeneous cycle, by three-dB coupler.Pump laser can be semiconductor or any kind laser of 980nm, 1480nm.Pumping/signal Wavelength division multiplexing optical coupler has three ports at least, is the coupler that adapts with pump laser.

Principle of the present invention is by answering apparatus for adjusting force to apply lateral stress and axial stress simultaneously in Bragg fiber grating, when applying lateral stress, in optical fiber, cause stress birfringence owing to elasto-optical effect, the reflection mould of two polarization direction quadratures of common Bragg fiber grating is separated on wavelength, utilize polarisation hole-burning effect to overcome the mode competition that Er-doped fiber uniform gain broadening causes, realize dual wavelength output stable under the normal temperature.Put on the accurate respectively control of big I of lateral stress and axial stress and the wavelength interval and the wavelength location of tuning two wavelength by change.For each lateral stress and axial stress, can change polarization state of light in the chamber by adjusting Polarization Controller again, thereby change the loss of wavelength on two orthogonal polarization orientation, to realize the place an order switch transition of wavelength and dual wavelength of normal temperature.The side-play amount of two wavelength with the pass of strain is:

${\mathrm{\&Delta;\&lambda;}}_1=2n_{\mathrm{eff}}\mathrm{\&Lambda;}\&lsqb;-\frac{n_{\mathrm{eff}}^2}{2}{\mathrm{<figure-callout\; id="11"\; label="p"\; filenames="A20031010706600071.png"\; state="\{\{state\}\}">p</figure-callout>}}_{11}{\mathrm{\&epsiv;}}_t+(1-\frac{n_{\mathrm{eff}}^2}{2})p_{12}{\mathrm{\&epsiv;}}_z\&rsqb;$

${\mathrm{\&Delta;\&lambda;}}_2=2n_{\mathrm{eff}}\mathrm{\&Lambda;}\&lsqb;-\frac{n_{\mathrm{eff}}^2}{2}{p}_{12}{\mathrm{\&epsiv;}}_t+(1-\frac{n_{\mathrm{eff}}^2}{2})p_{12}{\mathrm{\&epsiv;}}_z\&rsqb;$

Wherein, n _EffBe the effective refractive index of optical fiber, Λ is the grating cycle, p ₁₁, p ₁₂Be strain optical coefficient, ε _tBe lateral stress, ε _zBe axial stress.Apply the side-play amount that lateral stress and axial stress are two wavelength of may command simultaneously.

The present invention has easy, with low cost, the advantage such as steady operation at normal temperatures of tuning methods.

Description of drawings

Fig. 1 is that structure of the present invention is formed schematic diagram.

Fig. 2 is the profile that the present invention answers apparatus for adjusting force.

Fig. 3 is the profile that the present invention answers lateral stress adjusting part in the apparatus for adjusting force.

Fig. 4 is the vertical view that the present invention answers apparatus for adjusting force.

Fig. 5 is an output spectrum figure of the present invention.

Fig. 6 is the experimental curve diagram when applying axial stress separately.

Fig. 7 is the experimental curve diagram when applying lateral stress separately.

Among the figure: 1. pump laser 2. pumpings/signal Wavelength division multiplexing optical coupler 3. Er-doped fibers 4. Polarization Controllers 5. reflectors 6. tunable fiber Bragg grating mechanisms 7. optical isolators, 8. Bragg fiber gratings 9. are supported optical fiber 10. axial stress mechanical tuning devices 11. lateral stress mechanical tuning devices 12. stiff ends 13. guide rails 14. stepping mechanisms 15. fixed flat planars 16. lateral displacement stepping mechanisms

Embodiment

Below in conjunction with embodiment the present invention is elaborated

Embodiment

As Fig. 1, pump laser 1 (actual use be the 980nm semiconductor pump laser) is coupled in the laser cavity through the port a of pumping/signal Wavelength division multiplexing optical coupler 2, the port c of Wavelength division multiplexing optical coupler 2 links to each other with Er-doped fiber 3, connect a Polarization Controller 4 behind the Er-doped fiber, connect a Bragg fiber grating 8 behind the Polarization Controller, answer apparatus for adjusting force (10,11) to the fiber grating stress application, (actual what use is that tail optical fiber by two ports of a side of three-dB coupler links to each other to reflector 5, become Sagnac ring, a port tail optical fiber of opposite side) link to each other with the port b of Wavelength division multiplexing optical coupler 2.Pump light enters Er-doped fiber through Wavelength division multiplexing optical coupler 2, excite erbium optical fiber to produce gain, Sagnac ring and Bragg fiber grating 8 partner speculum and outgoing mirror, two light starting of oscillations in laser cavity of satisfying the wavelength of Bragg fiber grating conditioned reflex, and go out by Bragg fiber grating 8 outgoing.Polarization Controller 4 is used to control polarization state of light in the laser cavity, regulates Polarization Controller 4, can realize the conversion between single wavelength output and the dual wavelength output.Output spectrum is seen Fig. 5.

Pump light/flashlight wavelength-division multiplexed optical coupler 2 has three port a, b and c at least, is used for pump light and flashlight are coupled into Er-doped fiber; Er-doped fiber 3 must have one section suitable length, by the pump light excitation, as gain media; A Polarization Controller 4 is connected the Er-doped fiber back, and tunable Bragg fiber grating mechanism front is used to control polarization state of light in the laser cavity; A reflector 5 (the actual Sagnac that is made up of three-dB coupler that uses encircles reflector) is as a terminal reflector of laser cavity; A tunable Bragg grating mechanism 6 can apply axial stress and lateral stress to Bragg fiber grating simultaneously, and Fiber Bragg Grating 8 wherein is as the other end speculum and the outgoing mirror of laser cavity; Optical isolator 7 is used to isolate extraneous reverberation.

As Fig. 1-4, the stress adjusting bracket is made up of 10,11 two parts.The two ends tail optical fiber of fiber grating 8 is bonded on the guide rail 13 with epoxy resin, regulates guide rail and can apply axial stress to fiber grating, and Fig. 6 is wavelength shift amount and the strain relation figure when applying axial stress separately, and two wavelength are same to the reacting phase of axial stress.Bragg fiber grating 8 is clipped between two polymethyl methacrylate sheets 15, is clipped in the support optical fiber 9 that also has between the polymethyl methacrylate simultaneously, and its radius is identical with the used optical fiber of Bragg fiber grating.A screw clamps two polymethyl methacrylate sheets, and the suffered lateral stress of rotary screw scalable fiber grating, Fig. 7 concern between spacing and the screw anglec of rotation between two wavelength when applying lateral stress separately.

Reflector can be various broadbands or narrow band fiber or non-fiber reflection device, optical fiber and the non-fiber reflection devices such as Sagnac ring formed as the Bragg fiber grating in uniform period or non-homogeneous cycle, by three-dB coupler.

Pumping/signal Wavelength division multiplexing optical coupler is the coupler that adapts with pump laser.

Tunable fiber grating mechanism can apply lateral stress and axial stress simultaneously in Bragg fiber grating, when applying lateral stress, in optical fiber, cause stress birfringence owing to elasto-optical effect, the reflection mould of two polarization direction quadratures of common Bragg fiber grating is separated on wavelength, utilize polarisation hole-burning effect to overcome the mode competition that Er-doped fiber uniform gain broadening causes, realize the stable output of dual wavelength under the normal temperature; The size that puts on lateral stress by change is controlled the wavelength interval of two wavelength, and the size that puts on axial stress by change is controlled the absolute position of two wavelength.

For each lateral stress and axial stress, all can realize switch transition between single wavelength output of two of fiber laser and the dual wavelength output by adjusting described Polarization Controller.

Stress governor motion (10,11) can use the metal or the nonmetallic materials of high rigidity energy, as manganese steel, polymethyl methacrylate etc.Laser of the present invention can be worked at normal temperatures.

Claims (8)

1. single-double wave switchable wavelength position and adjustable at interval erbium doped fiber laser, it comprises: pump laser (1), pumping/signal Wavelength division multiplexing optical coupler (2), Er-doped fiber (3), Polarization Controller (4), reflector (5), tunable fiber Bragg grating mechanism (6) and optical isolator (7), it is characterized in that: the port (a) of Wavelength division multiplexing optical coupler (2) is connected with the output of pump laser (1), port (b) is connected with reflector (5), port (c) is connected with an end of Er-doped fiber (3), and the other end of Er-doped fiber (3) is connected with Polarization Controller (4); The other end of Polarization Controller (4) is connected with Fiber Bragg Grating mechanism (6), and the other end of Fiber Bragg Grating mechanism is connected with optical isolator (7), and laser is exported from the optical isolator other end; Tunable fiber Bragg grating mechanism (6) is made of Fiber Bragg Grating (8), support optical fiber (9), axial stress mechanical tuning device (10) and lateral stress mechanical tuning device (11), Bragg grating (8) is parallel with support optical fiber (9) to be put in the middle of two fixed flat planars (15), fixed flat planar (15) links to each other with lateral displacement stepping mechanism (16), tail optical fiber one end of Bragg grating (8) is fixed by stiff end (12), the tail optical fiber other end links to each other with stepping mechanism (14), carries out the stretching fine tuning of displacement (amount of deflection) by the differential thread adjuster; Axial stress mechanical tuning device (10) is made of stiff end (12), guide rail (13) and displacement (amount of deflection) stepping mechanism (14); Lateral stress mechanical tuning device (11) is made of two fixed flat planars (15) and lateral displacement stepping mechanism (16).

2. according to single-double wave switchable wavelength position described in the claim 1 and adjustable at interval erbium doped fiber laser, it is characterized in that: reflector, can be various broadbands or narrow band fiber or non-fiber reflection device, optical fiber and the non-fiber reflection devices such as Sagnac ring formed as the Bragg fiber grating in uniform period or non-homogeneous cycle, by three-dB coupler.

3. according to single-double wave switchable wavelength position described in the claim 1 and adjustable at interval erbium doped fiber laser, it is characterized in that: pump laser can be semiconductor or any kind laser of 980nm, 1480nm.

4. according to single-double wave switchable wavelength position described in the claim 1 and adjustable at interval erbium doped fiber laser, it is characterized in that: pumping/signal Wavelength division multiplexing optical coupler is the coupler that adapts with pump laser, and it has three ports at least.

5. according to single-double wave switchable wavelength position described in the claim 1 and adjustable at interval erbium doped fiber laser, it is characterized in that: tunable fiber grating mechanism can apply lateral stress and axial stress simultaneously in Bragg fiber grating, when applying lateral stress, in optical fiber, cause stress birfringence owing to elasto-optical effect, the reflection mould of two polarization direction quadratures of common Bragg fiber grating is separated on wavelength, utilize polarisation hole-burning effect to overcome the mode competition that Er-doped fiber uniform gain broadening causes, realize the stable output of dual wavelength under the normal temperature; The size that puts on lateral stress by change is controlled the wavelength interval of two wavelength, and the size that puts on axial stress by change is controlled the absolute position of two wavelength.

6. according to single-double wave switchable wavelength position described in the claim 1 and adjustable at interval erbium doped fiber laser, it is characterized in that:, all can realize that two single wavelength of fiber laser are exported and the switch transition of dual wavelength output by adjusting described Polarization Controller for each lateral stress and axial stress.

7. according to single-double wave switchable wavelength position described in the claim 1 and adjustable at interval erbium doped fiber laser, it is characterized in that: stress governor motion (10,11) can use the metal or the nonmetallic materials of high rigidity energy, as manganese steel, polymethyl methacrylate.

8. according to single-double wave switchable wavelength position described in the claim 1 and adjustable at interval erbium doped fiber laser, it is characterized in that: can work at normal temperatures.

Images