CN201965252U - Polarization device based on chirp long-period fiber grating of photonic crystal fiber - Google Patents

Abstract

The utility model provides a polarization device based on a chirp long-period fiber grating of a photonic crystal fiber. The chirp long-period fiber grating is written on the photonic crystal fiber through a carbon dioxide laser writing system, the grating section length of the chirp long-period fiber grating is 26mm, the number of grating grid periods arranged in monotonic increasing mode is 41, a starting period is 600 micrometers, and the incremental quantity of each grating grid period is 25 micrometers. The carbon dioxide laser writing system comprises a computer, a carbon dioxide laser, an incidence light source, an optical fixture and a spectrum analyzer. The polarization device has the advantages of being easy to produce and being applied to mass production. Simultaneously, the extinction ratio of the polarization device can reach 20 decibels, and working bandwidth is 100nm, so that the polarization device has good temperature stability.

Description

A Polarization Device Based on Photonic Crystal Fiber Chirped Long Period Fiber Grating

technical field

The utility model belongs to the technical field of optical fiber polarization, and relates to a polarization device based on a photonic crystal optical fiber chirped long-period optical fiber grating.

Background technique

With the rapid development of optical fiber communication and optical fiber sensing technology, the polarization state of light is becoming more and more important to the system and components. As an important branch of polarization devices, optical fiber polarization devices play a unique role. Fiber optic polarizers are favored due to their small size, light weight, low insertion loss, high extinction ratio, and strong compatibility with fiber optic systems. Optical fiber polarizers are widely used in passive devices such as optical isolators, optical circulators, optical switches, and optical modulators; in optical device test systems, fiber polarizers can be used in conjunction with other devices to obtain stable and flexible test conditions. Realize multi-parameter detection of devices; in fiber optic systems, fiber optic polarizers are key components for generating linearly polarized light; in fiber optic systems with polarization or phase as the main detection feature, fiber optic polarizers are important passive components, such as fiber optic gyroscopes , fiber optic current sensors, fiber optic hydrophone sensors, and coherent optical communication systems.

Traditional optical fiber polarizers mainly include metal-clad optical fiber polarizers, ring coil optical fiber polarizers, and microhole optical fiber polarizers. Existing optical fiber polarization devices have their own characteristics in terms of performance and manufacturing methods, but all have their own shortcomings. Metal-clad fiber polarizers are small in size, high in extinction ratio, and low in insertion loss, but the manufacturing process is relatively complicated and cannot be mass-produced. Coil fiber polarizers and microhole fiber polarizers are relatively simple in manufacturing process, but the size of the whole device is large, which reduces the practicality.

As a new type of optical fiber, photonic crystal fiber has been widely used in the field of optical fiber communication and optical fiber sensing due to its excellent optical properties, and is also used to make various optical devices. Polarization devices based on photonic crystal fiber long-period fiber gratings have been proposed, which can achieve an extinction ratio greater than 20dB and have a good temperature stability. However, the working bandwidth of this type of polarization device is only 11nm, which cannot meet the needs of practical applications.

Contents of the invention

The purpose of the utility model is to propose a polarizing device based on photonic crystal fiber chirped long-period fiber grating to overcome the problems of complex manufacturing process, large size and narrow working bandwidth of the existing polarizing device.

The technical solution of the present utility model is as follows:

A polarizing device based on a photonic crystal fiber chirped long-period fiber grating. A carbon dioxide laser writing system is used to write a chirped long-period fiber grating on a photonic crystal fiber. The length of the chirped long-period fiber grating is 26mm. There are 41 grid periods, the grid period presents a monotonous increase, the initial period is 600 μm, and the increment of each grid period is 25 μm. The carbon dioxide laser writing system described therein includes a computer, a carbon dioxide laser, an incident light source, an optical fiber clamp, and a spectrum analyzer; the computer is connected to the carbon dioxide laser, and the carbon dioxide laser is located directly above the photonic crystal fiber, and the two ends of the photonic crystal fiber are fixed by the optical fiber clamp. One end is connected to the incident light source, and the other end is connected to the spectrum analyzer.

The utility model has the advantages of: a polarizing device based on photonic crystal fiber chirped long-period fiber grating, using a carbon dioxide laser writing system to write chirped long-period fiber grating on the photonic crystal fiber, so the manufacturing method is simple, Can be used for mass production. At the same time, the polarization device can achieve an extinction ratio of 20dB and a working bandwidth of 100nm, which can meet the application requirements in the fields of optical fiber communication and optical fiber sensing. In addition, the polarizing device has a good temperature stability, which can meet the application system with unstable temperature environment.

Description of drawings

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

Fig. 2 is a schematic structural diagram of a carbon dioxide laser writing system.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described.

As shown in Figure 1, a polarizing device 1 based on a photonic crystal fiber chirped long-period fiber grating, using a carbon dioxide laser writing system to write a chirped long-period fiber grating on a photonic crystal fiber, the chirped long-period fiber grating The length of the grid area is 26 mm, and there are 41 grid periods in total. The grid period presents a monotonous increase. The initial period is 600 μm, and the increment of each grid period is 25 μm.

As shown in Figure 2, the described carbon dioxide laser writing system comprises computer 2, carbon dioxide laser 3, incident light source 4, optical fiber fixture 5 and spectrum analyzer 6; Computer 2 connects carbon dioxide laser 3, and carbon dioxide laser 3 is positioned at photonic crystal fiber 1 Vertically above, both ends of the photonic crystal fiber 1 are fixed by the fiber clamp 5 , one end is connected to the incident light source 4 , and the other end is connected to the spectrum analyzer 6 .

The utility model is based on the following principles:

Photonic crystal fiber is a new type of optical fiber, which is composed of pure silica, and the cladding is distributed with wavelength-level air holes periodically arranged in the radial direction and extending along the fiber axis. When the carbon dioxide laser writing system is used to write chirped long-period fiber gratings on the photonic crystal fiber, due to the large amount of energy released by the carbon dioxide laser, the quartz absorbs heat and melts when heated, causing the air holes in the photonic crystal fiber cladding to collapse or deform. The refractive index of quartz on one side of the photonic crystal fiber changes, and at the same time, it collapses to form structural asymmetry. The two polarization modes will have different transmission losses during transmission due to the different refractive index distribution and structural asymmetry of the photonic crystal fiber. So the chirped long-period fiber grating can realize the polarization effect. In this embodiment, we use a solid photonic crystal fiber with a core diameter of 12 μm, an air hole diameter of 3.6 μm, and an air hole spacing of 7.5 μm. The manufactured chirped long-period fiber grating has a polarization device extinction ratio of 20dB and a working bandwidth of 100nm.

Claims (2)

1. A polarization device based on a photonic crystal fiber chirped long-period fiber grating, characterized in that a carbon dioxide laser writing system is used to write a chirped long-period fiber grating on the photonic crystal fiber, and the grid of the chirped long-period fiber grating The length of the zone is 26 mm, and there are 41 grid periods in total. The grid period presents a monotonous increase, the initial period is 600 μm, and the increment of each grid period is 25 μm. 2. A kind of polarizing device based on photonic crystal fiber chirped long-period fiber grating according to claim 1, wherein said carbon dioxide laser writing system comprises computer, carbon dioxide laser, incident light source, optical fiber fixture and spectrum The analyzer; the computer is connected to the carbon dioxide laser. The carbon dioxide laser is located directly above the photonic crystal fiber. the

Images