CN201242628Y - High Power Fiber Optic Isolators - Google Patents

Abstract

A high-power optical fiber isolator, comprising a core component and a first half-wave plate (4), a first polarization displacement plate (3), and a first coupling lens (2) arranged symmetrically at both ends of the core component and arranged in sequence , the first double-clad fiber head (1) and the second half-wave plate (6), the second polarization displacement plate (7), the second coupling lens (8), and the second double-clad fiber head (9), so The first half-wave plate (4) and the second half-wave plate (6) are respectively adjacent to the core component, the core component is a Faraday optical rotator (5), and the Faraday optical rotator (5) includes a magneto-optic Crystal TGG and magnets. The utility model solves the technical problem that the existing high-power isolator in the background technology cannot be applied near the 1064nm wave band. The utility model adopts TGG crystal, which has large magneto-optical constant, low light loss, high thermal conductivity and high laser damage threshold near the 1064nm wave band.

Description

High Power Fiber Optic Isolators

technical field

The utility model relates to an optical fiber isolator, in particular to an optical fiber isolator capable of carrying high-power laser input and output.

Background technique

With the development of high-power fiber lasers, the isolation of reflected light in the optical path has become an important problem that must be solved. A high-power fiber optic isolator is a non-reciprocal passive device that only allows light to transmit forward along the optical path and can withstand high power. The optical path system has adverse effects. Installing a high-power fiber optic isolator between the high-power semiconductor laser and the optical transmission system can greatly reduce the adverse effects of reflected light on the spectral output power stability of the light source. In the application of high-energy signals, high-speed direct modulation, and direct detection optical fiber communication systems, the backward transmission of light will generate additional noise, which will degrade the performance of the system, which requires high-power optical fiber isolators to eliminate. Installing a high-power fiber isolator at both ends of the doped fiber in the high-power fiber amplifier can prevent the back-reflected light from entering the signal source and cause severe fluctuations in the signal source, and can improve the working stability of the high-power fiber amplifier. High-power fiber optic isolators have become one of the bottleneck technologies restricting the development of high-power fiber lasers to higher power.

At present, the use of ytterbium-doped double-clad fiber and cladding pumping technology based on double-clad fiber has achieved a major technological breakthrough in high-power fiber lasers. The double-clad fiber has an inner cladding added to the conventional fiber, and its core is generally doped with rare earth ions, which is the transmission waveguide of the single-mode laser. Existing high-power fiber lasers mostly output around the 1064nm band, and the high-power fiber isolators used in them also need to have a higher laser carrying power threshold, higher isolation and lower insertion loss near the 1064nm band.

Optical fiber devices used in optical fiber communication systems can withstand optical power below 500mw, and these optical fiber devices are called low-power devices. For optical fiber devices, they can carry more than 500mw of optical power, which is called high-power devices. At present, the commonly used communication window bands are 1550nm and 1310nm, and the optical fiber isolators used in the system are also designed and manufactured corresponding to these two bands. The core component of this type of fiber optic isolator is yttrium iron garnet (YIG) crystal, which has good transmittance in the 1550nm and 1310nm bands, but has a large absorption near the 1064nm band, and the transmittance is low, so it cannot carry High power, so it cannot be used in high-power fiber lasers near the 1064nm band.

Contents of the invention

The purpose of the utility model is to provide an optical fiber isolator capable of carrying high-power laser input and output, which solves the technical problem that the existing high-power isolator in the background technology cannot be applied near the 1064nm band.

The core element of the utility model adopts the Faraday optical rotator, which is composed of several main parts such as magneto-optical materials, magnets and adjustment mechanisms. Magneto-optical materials in the visible and near-infrared bands are TGG crystals (Terbium Ga1lium Garnet, terbium gallium garnet), terbium-doped glasses, etc., all of which have high Verdet constants and transmittances, as well as good mechanical, physical, and optical properties. optical properties.

The technical scheme of the utility model is:

A high-power optical fiber isolator, including a core component and a first half-wave plate 4, a first polarization displacement plate 3, a first coupling lens 2, and a first double-clad layer arranged symmetrically at both ends of the core component and arranged in sequence The optical fiber head 1 is connected with the second half-wave plate 6, the second polarization displacement plate 7, the second coupling lens 8, and the second double-clad fiber head 9, and the first half-wave plate 4 and the second half-wave plate 6 are respectively in phase with each other. Adjacent to the core component, the special feature is that the core component is a Faraday optical rotator 5, and the Faraday optical rotator 5 includes a magneto-optic crystal TGG, a magnet, an adjustment mechanism, and the like.

Both the first double-clad fiber head 1 and the second double-clad fiber head 9 are composed of a double-clad fiber 001, a capillary 002 and an adhesive 003, and the adhesive 003 is fixedly arranged in the double-clad fiber in the capillary 002. A layer of optical fiber 001 and capillary 002, the surface of the capillary 002 and the double-clad optical fiber 001 are on the same plane, have a certain bevel, and are coated with a high-power anti-reflection coating.

The first polarization displacement plate 3 and the first half-wave plate 4 are glued together, and the cross-sectional area of the first half-wave plate 4 is half of that of the first polarization displacement plate 3 .

The angle between the optical axes of the first polarization displacement plate 3 and the first half-wave plate 4 is 22.5°.

The second polarization displacement plate 7 and the second half-wave plate 6 are glued together, and the cross-sectional area of the second half-wave plate 6 is half of the second polarization displacement plate 7 .

The angle between the optical axes of the second polarization displacement plate 7 and the second half-wave plate 6 is 22.5°.

The angle between the optical axis of the TGG crystal and the first polarization displacement film 3 is 22.5°; the angle between the optical axis of the TGG crystal and the second polarization displacement film 7 is 90°.

Both the above-mentioned first coupling lens 2 and the second coupling lens 8 are cylindrical lenses or aspherical lenses, and anti-reflection coatings capable of carrying high power are coated on the surfaces of the lenses.

The walk-off planes of the first polarization displacement film 3 and the second polarization displacement film 7 are parallel, the walk-off amounts are the same, and the walk-away directions are the same.

The utility model has the advantages of:

The utility model adopts the double-clad optical fiber as the input and output optical fiber, the mode field area of the optical fiber is increased by more than 10 times compared with the ordinary single-mode optical fiber, the power density of the fiber core is greatly reduced, and the thermal light generated by the high-power laser is effectively simulated. question.

The utility model adopts TGG crystal, which has large magneto-optical constant, low light loss, high thermal conductivity and high laser damage threshold near the 1064nm wave band.

Description of drawings

Fig. 1 is the structural representation of the double-clad optical fiber head of the present invention;

Fig. 2 is the structural representation of the specific embodiment of the utility model;

Fig. 3 is a schematic diagram of an embodiment of the utility model.

Reference signs:

1—the first double-clad fiber head; 2—the first coupling lens; 3—the first polarization displacement plate; 4—the first half-wave plate; 5—the Faraday optical rotator; 6—the second half-wave plate; 7— 8—the second coupling lens; 9—the second double-clad fiber head; 001—double-clad fiber; 002—capillary; 003—adhesive.

Detailed ways:

The utility model includes the first double-clad optical fiber head 1, the first coupling lens 2, the first polarization displacement plate 3, the first half-wave plate 4, the Faraday optical rotator 5, and the second half-wave plate from left to right 6. The second polarization shifter 7, the second coupling lens 8 and the second double-clad optical fiber head 9 are composed. Wherein: the walk-off planes of the first polarization displacement plate 3 and the second polarization displacement plate 7 are parallel, the walk-off amount is the same, and the walk-off direction is the same; the optical axis clamp between the first polarization displacement plate 3 and the first half-wave plate 4 Angle is 22.5 °, the optical axis angle between the second polarization displacement plate 7 and the second half-wave plate 6 is 22.5 °, the optical axis angle between the first polarization displacement plate 3 and the TGG crystal is 45 °, and The angle between the optical axes of the second polarization displacement plates 7 is 90°.

The utility model realizes the high-power laser isolation in this way: the high-power laser enters the double-clad optical fiber 001, is collimated by the first coupling lens 2 and becomes parallel light, and the parallel light enters the first polarization displacement plate 3 and is divided into o light and e light; o light enters the half-wave plate 4 along the original direction and rotates its polarization state clockwise by 45°, enters the Faraday rotator 5, and after the o light passes through the Faraday rotator 5, the polarization state rotates 45° clockwise again, becoming The e light directly enters the second polarization displacement film 7; the e light is refracted by the first polarization displacement film 3 and deviates from the distance L along the positive direction of the Y axis, and directly enters the Faraday rotator 5, and after the e light passes through the Faraday rotator 5, The polarization state rotates 45° in the clockwise direction and enters the second half-wave plate 6, and the polarization state rotates 45° in the clockwise direction again to become o light and enters the second polarization displacement plate 7; The polarization displacement plate 7 is refracted and deviates from the distance L along the positive direction of the Y axis, merges with the o light, and focuses it into the second double-clad optical fiber 9 through the second coupling lens 8 to realize the transmission of the forward light. When the light enters in reverse from the second double-clad fiber head 9, it becomes parallel light through the second coupling lens 8, and the parallel light enters the second polarization displacement plate 7 and is divided into o light and e light; the o light follows the original direction After entering the second half-wave plate 6, the polarization state is rotated counterclockwise by 45°, and enters the Faraday rotator 5. Because of the non-reciprocity of the Faraday rotator, the polarization state of o light still rotates clockwise by 45° after passing through the Faraday rotator 5, o The light enters the first polarization displacement film 3, and exits along the original direction by a distance L away from the positive direction of the Y axis, and cannot enter the effective aperture of the first coupling lens 2, and thus cannot enter the double-clad optical fiber 001, thereby realizing the o light isolation; e light enters the second polarization displacement plate 7 and refracts along the negative direction of the Y axis to deviate from the distance L and enters the Faraday rotator 5. Because of the non-reciprocity of the Faraday rotator, the e light is polarized after passing through the Faraday rotator 5 The polarization state also rotates 45° clockwise, enters the first half-wave plate 4, the polarization state rotates 45° counterclockwise, and then enters the first polarization displacement film 3, refraction occurs and exits along the negative direction of the Y axis by a distance L, and cannot enter In the effective aperture of the first coupling lens 2, the double-clad optical fiber 001 cannot enter, thereby realizing the isolation of e-light. In this way, because the reverse light enters the double-clad light 001, the isolation of the reverse light is realized.

Claims (9)

1. high-power fiber optic isolator, first half-wave plate (4) that comprises a core component and be symmetricly set in these core component two ends and be arranged in order, the first polarization shift sheet (3), first coupled lens (2), the first doubly clad optical fiber head (1) and second half-wave plate (6), the second polarization shift sheet (7), second coupled lens (8), the second doubly clad optical fiber head (9), described first half-wave plate (4) and the adjacent described core component of second half-wave plate (6) difference, it is characterized in that: described core component is faraday's optical rotator (5), and this faraday's optical rotator (5) comprises magneto-optical crystal TGG and magnet.

2. according to the described high-power fiber optic isolator of claim 1, it is characterized in that: the described first doubly clad optical fiber head (1) and the second doubly clad optical fiber head (9) constitute by doubly clad optical fiber (001), kapillary (002) and bonding agent (003), described bonding agent (003) is fixedly set in doubly clad optical fiber (001) and the kapillary (002) in the kapillary (002), described kapillary (002) and doubly clad optical fiber (001) surface are same plane, have a fixed inclination and are coated with the antireflecting film of anti-the high power.

3. according to the described high-power fiber optic isolator of claim 1, it is characterized in that: described first polarization shift sheet (3) and first half-wave plate (4) are glued together, and the sectional area of described first half-wave plate (4) is 1/2nd of the first polarization shift sheet (3).

4. according to the described high-power fiber optic isolator of claim 3, it is characterized in that: the optical axis included angle between described first polarization shift sheet (3) and first half-wave plate (4) is 22.5 °.

5. according to the described high-power fiber optic isolator of claim 1, it is characterized in that: described second polarization shift sheet (7) and second half-wave plate (6) are glued together, and the sectional area of described second half-wave plate (6) is 1/2nd of the second polarization shift sheet (7).

6. according to the described high-power fiber optic isolator of claim 5, it is characterized in that: the optical axis included angle between described second polarization shift sheet (7) and second half-wave plate (6) is 22.5 °.

7. according to the described high-power fiber optic isolator of claim 1, it is characterized in that: the optical axis included angle between the described TGG crystal and the first polarization shift sheet (3) is 22.5 °; And the optical axis included angle between the second polarization shift sheet (7) is 90 °.

8. according to the arbitrary described high-power fiber optic isolator of claim 1～7, it is characterized in that: described first coupled lens (2) and second coupled lens (8) all adopt post lens or non-spherical lens, and are coated with at lens surface and can carry high-power antireflecting film.

9. described according to Claim 8 high-power fiber optic isolator is characterized in that: the walking of the described first polarization shift sheet (3) and the second polarization shift sheet (7) from plane parallel, walk from amount identically, and walk from direction identical.

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