CN205565282U - Tunable narrow linewidth lasers output device based on micro flutes optic fibre - Google Patents

Abstract

The utility model discloses an adjustable narrow line width laser output device based on a micro-groove optical fiber. The utility model is suitable for the field of tunable narrow-linewidth fiber lasers. The tunable filter is used as a wavelength tuning device, the erbium-doped fiber is used as a gain medium, and the micro-groove fiber is used to realize Rayleigh gain accumulation and linewidth compression to realize tunable narrow linewidth laser output. The utility model can be applied to the fields of optical communication, gas sensing, environment monitoring and the like, and has the advantages of simple structure, low cost and the like.

Description

Tunable narrow linewidth laser output device based on micro-groove fiber

technical field

The utility model belongs to the technical field of lasers, and in particular relates to an adjustable narrow line width laser output device based on a micro-groove optical fiber.

Background technique

Narrow linewidth fiber lasers have broad application prospects in the fields of optical fiber communication, optical fiber sensing, military, industrial processing, and optical information processing. In particular, tunable narrow-linewidth fiber lasers play an important role in wavelength-division multiplexing fiber-optic communication and fiber-optic sensing systems.

Existing methods for forming narrow linewidth single longitudinal mode laser beams mainly include short cavity, saturable absorber, annular cavity, etc., but most of them have the defects of complex structure, large volume, high cost, and unsatisfactory linewidth compression effect. Application of tunable narrow linewidth single longitudinal mode laser beam.

Theory has proved that Rayleigh scattering is an effective linewidth compression mechanism. If Rayleigh scattering can be used to achieve laser linewidth compression, the structure of ultra-narrow linewidth lasers will be simplified. Usually, Brillouin scattering and Rayleigh scattering exist almost at the same time, and the gain coefficient of ordinary fiber for Brillouin scattering is several orders of magnitude higher than that of Rayleigh scattering, while Brillouin scattering has a negative impact on linewidth compression , so the effective suppression of Brillouin scattering and the realization of Rayleigh gain accumulation are of great significance for the formation of tunable narrow linewidth single longitudinal mode laser beams.

Contents of the invention

The utility model aims at the deficiencies of the prior art, and proposes a tunable narrow-linewidth laser output device based on a micro-groove optical fiber.

The utility model comprises a 980nm pump laser with an output power greater than 100mW, a 980nm/1550nm wavelength division multiplexer, an erbium-doped optical fiber with a length of 2 meters to 10 meters, a three-port circulator, an adjustable narrowband filter, A three-port circulator, a microgroove fiber, a variable optical attenuator, a Sagnac ring, and a 1*2 optical coupler.

The port of the pump laser is connected to the first port of the wavelength division multiplexer by optical fiber, and the second port of the wavelength division multiplexer is connected to one end of the erbium-doped fiber; the other end of the erbium-doped fiber is connected to one end of the tunable narrowband filter Optical fiber connection, the other end of the adjustable narrowband filter is connected to the first port of the three-port circulator, the second port of the three-port circulator is connected to one end of the micro-groove fiber, and the other end of the micro-groove fiber is connected to the The variable optical attenuator is connected, and the other end of the variable optical attenuator is connected to the Sagnac ring; the third port of the three-port circulator is connected to the input fiber of the 1*2-port coupler, and the 1*2-port coupler’s The first output end is connected to the third port of the wavelength division multiplexer through an optical fiber, and the second output end of the 1*2 end coupler is used as the output end of the ultra-narrow linewidth laser.

The micro-groove optical fiber is a single-mode optical fiber inscribed with symmetrical grooves. There are multiple pairs of symmetrical grooves in the axial direction, and the depth of each groove is 6-7 microns.

Further, the axial length of the single groove is 1.8-2cm, the axial center distance between two adjacent grooves is 4.5-6m, and the numerical ratio of the minimum diameter of the groove to the outer diameter of the single-mode optical fiber is 24:25 ~18:25.

The utility model is suitable for the field of tunable narrow-linewidth optical fiber lasers, uses micro-groove optical fibers to realize Rayleigh gain accumulation and linewidth compression, and is compatible with other optical fiber devices.

Description of drawings

Fig. 1 a is the structural representation of the utility model;

Figure 1b is a schematic structural view of a micro-groove fiber;

Fig. 2 is a spectrum diagram of outputting narrow linewidth lasers with different wavelengths in the embodiment of the utility model.

detailed description

As shown in Figure 1a and Figure 1b, the present embodiment includes a 980nm pump laser 1, a wavelength division multiplexer 2, a section of erbium-doped optical fiber 3, an adjustable narrowband filter 4, a three-port circulator 5, a section Micro-groove fiber 6, a variable optical attenuator 7, a Sagnac ring 8, and a 1*2 optical coupler 9.

The micro-groove fiber 6 in this embodiment is made of a common single-mode fiber 10 through femtosecond laser microprocessing, and two symmetrical grooves 6-1 with a depth of 6-7 microns are written on the surface of the single-mode fiber with a femtosecond laser. , through multiple writing operations, multiple pairs of micro-groove regions are formed on ordinary single-mode optical fibers. The micro-groove fiber is connected to the laser, so that the length of the resonant cavity of the laser is equal to or greater than 110m. The multiple micro-groove areas on the ordinary single-mode fiber can effectively suppress Brillouin scattering, satisfying the accumulation of Rayleigh scattering, and realizing Laser line width compression effect.

In order to achieve a better balance between the transmission loss of light in the micro-groove fiber and the suppression effect on the Brillouin gain, the parameters of the micro-groove fiber are set as follows: the axial length of a single micro-groove area is 1.8-2cm, Each micro-groove area 6-1 is arranged at equal intervals, and the distance between the axial centers of two adjacent pairs of micro-groove areas (see the range indicated by the mark M in Fig. 1b) is 4.5-6m. The ratio of the minimum diameter in the micro-groove region 6-1 to the outer diameter of a common single-mode optical fiber is between 24:25 and 18:25.

The port of 980nm pumping laser 1 is connected with the first port optical fiber of wavelength division multiplexer 2, and the second port of wavelength division multiplexer 2 is connected with one end optical fiber of erbium-doped optical fiber 3; One end of the adjustable narrowband filter 4 is connected to an optical fiber, the other end of the adjustable narrowband filter 4 is connected to the first optical fiber of the three-port circulator 5, and the second port of the three-port circulator 5 is connected to one end of the microgroove optical fiber 6 connection, the other end of the micro-groove optical fiber 6 is connected to the variable optical attenuator 7, and the other end of the variable optical attenuator 7 is connected to the Sagnac ring 8; the third port of the three-port circulator 5 is connected to 1* The input end of the 2-port coupler 9 is connected to an optical fiber, the first output of the 1*2-port coupler 9 is connected to the third port of the wavelength division multiplexer 2 by an optical fiber, and the second output of the 1*2-port coupler 9 is used as The output port of the ultra-narrow linewidth laser.

The working process of this device: turn on the 980nm pump laser 1, the output 980nm laser enters the erbium-doped fiber 3 through the wavelength division multiplexer 2, and the erbium-doped fiber 3 absorbs the 980nm laser, thereby providing a broadband light source; adjustable narrow-band filter 4 It is a wavelength selection element, the light selected by the adjustable narrowband filter 4 is injected into the micro-groove fiber 6, the variable optical attenuator 7 and the Sagnac ring 8 through the second port of the three-port circulator 5, and the three-port circulator The third port of 5 forms a complete ring laser cavity with the third port of the 1*2-port coupler 9 and the wavelength division multiplexer 2. The Sagnac ring 8 and the variable optical attenuator 7 provide a very weak seed light for the microgroove fiber 6, and the variable optical attenuator 6 controls the intensity of the seed light to avoid the backward Rayleigh of narrow linewidth The signal is submerged, thereby increasing the probability of backscattering. Rayleigh scattered light with a narrow linewidth circulates in the ring cavity, and finally forms a laser oscillation, which outputs a narrow The line-width laser signal can output narrow-line-width lasers with different wavelengths by adjusting the adjustable narrow-band filter 4 . Fig. 2 is a spectrum diagram of a continuously tunable narrow-linewidth laser with an output wavelength from 1549.57nm to 1553.93nm in an embodiment of the utility model. The linewidth of the output laser is less than 10kHz.

The utility model is suitable for the field of tunable narrow-linewidth fiber lasers. The tunable filter is used as a wavelength tuning device, the erbium-doped fiber is used as a gain medium, and the micro-groove fiber is used to realize Rayleigh gain accumulation and linewidth compression to realize tunable narrow linewidth laser output. The utility model can be applied to the fields of optical communication, gas sensing, environment monitoring and the like, and has the advantages of simple structure, low cost and the like.

Claims (2)

1. A multi-wavelength narrow-linewidth laser output device based on a microgroove fiber, characterized in that it includes a 980nm pump laser with an output power greater than 100mW, a 980nm/1550nm wavelength division multiplexer, and a length of 2 meters to 10 meters Erbium-doped fiber, a three-port circulator, a tunable narrowband filter, a three-port circulator, a microgroove fiber, a variable optical attenuator, a Sagnac ring, a 1*2 optical coupler device; The port of the pump laser is connected to the first port of the wavelength division multiplexer by optical fiber, and the second port of the wavelength division multiplexer is connected to one end of the erbium-doped fiber; the other end of the erbium-doped fiber is connected to one end of the tunable narrowband filter Optical fiber connection, the other end of the adjustable narrowband filter is connected to the first port of the three-port circulator, the second port of the three-port circulator is connected to one end of the micro-groove fiber, and the other end of the micro-groove fiber is connected to the The variable optical attenuator is connected, and the other end of the variable optical attenuator is connected to the Sagnac ring; the third port of the three-port circulator is connected to the input fiber of the 1*2-port coupler, and the 1*2-port coupler’s The first output end is connected to the third port of the wavelength division multiplexer by optical fiber, and the second output end of the 1*2 end coupler is used as the output end of the ultra-narrow linewidth laser; The micro-groove optical fiber is a single-mode optical fiber inscribed with symmetrical grooves. There are multiple pairs of symmetrical grooves in the axial direction, and the depth of each groove is 6-7 microns. 2. The multi-wavelength narrow-linewidth laser output device based on micro-groove fiber according to claim 1, characterized in that: the axial length of the single groove is 1.8-2 cm, and the axes of two adjacent grooves The distance to the center is 4.5-6m, and the ratio of the minimum diameter of the groove to the outer diameter of the single-mode optical fiber is 24:25-18:25.