CN203037892U - High power optical fiber collimator - Google Patents

Abstract

The utility model relates to an optical fiber collimator. The technical problem to be solved is to provide a high-power optical fiber collimator, which can reduce the reflection loss of the end face, aiming at the deficiencies of the prior art. It is characterized in that: the optical fiber collimator is integrally formed by welding an optical fiber and a multimode optical fiber preform; the rear end of the multimode optical fiber preform used to function as a self-focusing lens has a tapered transition zone, and the tapered The diameter of the rearmost end of the shaped transition zone is equivalent to the diameter of the optical fiber; the front end of the optical fiber is welded to the rearmost end of the tapered transition zone. The utility model adopts the quartz-based multi-mode optical fiber preform rod and the optical fiber to be well fused together. The multi-mode optical fiber preform rod has the characteristic of gradient refractive index and can realize the function of the self-focusing lens; since the self-focusing lens and the optical fiber are fused together , can eliminate the air gap between the two, reducing the damage of high-power light to the end face, thereby enhancing the high resistance to light damage of the high-power fiber collimator.

Description

A high power fiber collimator

technical field

The utility model relates to an optical fiber collimator.

technical background

Fiber collimators are basic optical devices in fiber optic communication and fiber optic sensing systems. It is composed of pigtail and collimating lens (GRIN Lens or C-Lens), with low insertion loss, high return loss, long working distance, wide working wavelength range, small beam divergence angle, high stability and reliability, Small size, light weight and other characteristics. Fiber collimator is to transform the divergent beam emitted from the fiber into a parallel beam, or to converge the parallel beam and couple it into the fiber with high efficiency to improve the coupling efficiency of the fiber system. It is the basic device for making a variety of optical devices. It can be conveniently used in various optical passive devices, such as attenuators, optical splitters, isolators, filters, optical switches and wavelength division multiplexers, etc.

Fiber collimators can be divided into single-mode fiber collimators and multimode fiber collimators according to different fibers. Among them, the multimode fiber collimator is widely used in energy transmission due to its high coupling efficiency. According to the different types of lenses used, the existing fiber optic collimators can be divided into three categories, namely self-focusing lens type collimators, C-lens lens type collimators and ball lens type collimators.

The optical fiber collimator structure in the prior art is a two-piece set, which is composed of an optical fiber ferrule and a lens or lens group that acts as a collimator. By adjusting the relative position of the optical fiber head and the collimator lens, the light output of the outgoing beam can be adjusted. The power value is the largest, and finally the fiber optic ferrule and the glass sleeve are glued and fixed to complete the preparation of the entire fiber collimator. There is a gap between the fiber end face and the lens end face of the fiber collimator with this structure, resulting in the reflection loss generated on the two end faces of the collimator, which is easy to damage the end face, and reduces the optical damage resistance of the optical fiber passive device.

Utility model content

The technical problem to be solved by the utility model is to provide a high-power optical fiber collimator for the deficiencies of the prior art, which can reduce the reflection loss of the end face and improve the optical damage resistance of the optical fiber collimator.

For solving the problems of the technologies described above, the technical solution of the utility model is:

A high-power optical fiber collimator, characterized in that: the optical fiber collimator is integrally formed by welding an optical fiber 1 and a multimode optical fiber preform 4; the multimode optical fiber preform 4 used to act as a self-focusing lens The end has a tapered transition zone 3, the diameter of the last end of the tapered transition zone 3 is equivalent to the diameter of the optical fiber; the front end of the optical fiber 1 is welded to the last end of the tapered transition zone 3.

The diameter _d2 of the multimode optical fiber preform 4 is 3 to 5 times the diameter _d1 of the optical fiber 1; the overall length _L2 of the multimode optical fiber preform 4 with the tapered transition zone 3 is 7.7mm±0.4 mm; the length of the tapered transition zone 3 is 2.9mm±0.2mm.

The utility model can bring the following beneficial effects:

The utility model adopts the quartz-based multi-mode optical fiber preform rod and the optical fiber to be well fused together. The multi-mode optical fiber preform rod has the characteristics of gradient refractive index, so that the beam can be expanded and collimated, and the function of the self-focusing lens can be realized. ; Since the self-focusing lens and the optical fiber are fused together, the air gap between the two can be eliminated, and the damage to the end face of the high-power light is reduced, thereby enhancing the high-power optical damage resistance of the high-power fiber collimator.

Description of drawings

Fig. 1: Structural schematic diagram of an embodiment of the utility model

Figure 2: Schematic block diagram of the isolator system made using the embodiment shown in Figure 1

Fig. 3: The functional block diagram of the filter system made by the embodiment shown in Fig. 1

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail.

The design principle of the utility model is as follows: high-power optical fiber passive devices, such as filters, isolators, etc., are composed of multiple optical components inside, so there are multiple component interfaces, so there will be a large reflection loss. So many interfaces will not only cause a large loss, but generally speaking, although high-intensity light will generate a lot of heat after passing through, it is difficult to melt the crystal and optical fiber, but it is easy to cause damage to the optical film on the surface of the crystal element. Due to the close distance between discrete components, damage to the thin film of one optical component can easily cause damage to the thin film of other optical components, thereby destroying the entire passive device. In fiber isolators and filters, self-focusing lenses are generally used to expand and collimate the optical path, and the reflection loss generated on the two end faces of the collimator will greatly reduce the high resistance to optical damage of the entire device. Therefore, in order to enhance the high resistance to light damage of passive devices, it is necessary to minimize the number of discrete components on the basis of ensuring optical performance.

The structure of a high-power fiber collimator according to an embodiment of the present invention is shown in FIG. 1 . In Fig. 1, 1 is an optical fiber, 2 is a fusion splicing zone, 3 is a tapered transition zone, and 4 is a multimode optical fiber preform acting as a self-focusing lens. In this embodiment, the diameter d ₂ of the multimode optical fiber preform 4 functioning as a self-focusing lens is four times the diameter d ₁ of the optical fiber 1; L ₁ = 4.8mm; L ₂ = 7.7mm.

This structure fuses the optical fiber 1 used in the device and the multimode optical fiber preform rod 4 together. The rear end of the multimode optical fiber preform 4 has a tapered transition zone 3 , and the diameter of the rearmost end of the tapered transition zone 3 is equivalent to the diameter of the optical fiber 1 . The benefits of adopting this structure are: on the one hand, the multimode optical fiber preform 4 has the characteristics of a graded refractive index, so that the beam can be expanded and collimated to realize the function of a self-focusing lens; on the other hand, due to the self-focusing lens and The optical fiber 1 is fused together, which can eliminate the air gap between the two, and reduce the damage of the high-power light to the end face, thereby enhancing the high light damage resistance of the high-power fiber collimator. The main reason for using the graded-index multimode optical fiber preform 4 as the self-focusing lens is that the preform 4 is based on quartz, and its melting point is basically the same as that of the optical fiber. However, the general self-focusing lens contains multiple components, and its melting point is relatively low, so it is difficult to perform fusion with the optical fiber 1 .

The system block diagrams of the fiber isolator and filter constructed with high-power fiber collimator are shown in Fig. 2 and Fig. 3, respectively.

In the block diagram of the isolator system shown in Figure 2, the forward transmission of the beam is taken as an example to illustrate the working principle of the high-power fiber collimator in the isolator. When the light beam is input from the optical fiber and passes through the high-power fiber collimator 1 composed of multimode fiber preforms, the light beam is collimated and then enters the birefringent crystal P ₁ , the light beam is divided into o light and e light, the polarization directions of which are perpendicular to each other, and the propagation direction When they pass through the 45° Faraday rotator, the polarization planes of the outgoing o-light and e-light are rotated by 45° respectively, because the crystal axis of the second birefringent crystal P ₂ is exactly in the shape of the first crystal The included angle is 45°, so the o-light and e-light are refracted together by P ₂ to synthesize two beams of parallel light with a small distance, and then enter the high-power fiber collimator 2 to couple into the fiber core.

In the schematic block diagram of the filter system shown in Figure 3, when the light beam is input from the optical fiber and passes through the high-power fiber collimator 1 composed of multimode fiber preforms, the light beam is collimated and then enters the filter (the filter has a pass through for a certain wavelength range. Band, the wavelength outside the bandwidth range is a stop band, so as to form the required filtering characteristics), and then enter the high-power fiber collimator 2 to couple into the fiber core.

Claims (2)

1. A high-power optical fiber collimator, characterized in that: the optical fiber collimator is formed by fusion of an optical fiber (1) and a multimode optical fiber preform (4); The rear end of the mode fiber preform (4) has a tapered transition zone (3), and the diameter of the rear end of the tapered transition zone (3) is equivalent to the diameter of the optical fiber; the front end of the optical fiber (1) and the tapered transition Zone (3) is welded at the last end. 2. A high-power optical fiber collimator according to claim 1, characterized in that: the diameter _d2 of the multimode optical fiber preform (4) is 3 to 5 times the diameter _d1 of the optical fiber (1); The overall length L ₂ of the multimode optical fiber preform (4) with the tapered transition zone (3) is 7.7mm±0.4mm; the length of the tapered transition zone (3) is 2.9mm±0.2mm.

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