CN105549156A - Microballoon resonance filter integrated into suspension core fiber - Google Patents

Abstract

The invention discloses a microsphere resonant filter integrated in a suspended core optical fiber. Including suspended core fiber and microspheres, suspended core fiber includes cladding and core, the cladding is a ring structure, the inside of the cladding is an air hole, the inner diameter of the cladding is 50-250 microns, the distance between the inner diameter and the outer diameter of the cladding The difference is 20-40 microns, the fiber core is suspended on the inner wall of the cladding, the diameter of the fiber core is 9-13 microns, the refractive index of the fiber core is greater than the direct refractive index of the cladding; the diameter of the microsphere is 50-200 microns, and the refractive index of the microsphere is greater than or equal to The refractive index of the core, the microspheres are located inside the cladding, the microspheres are bonded to the core through local heating, and the two ends of the suspended core fiber are directly coupled with the single-mode fiber by aligning the core. The invention has the advantages of firm packaging, compactness, high integration, strong anti-interference ability and suitable for long-term stable work.

Description

A Microsphere Resonator Filter Integrated in Suspended Core Optical Fiber

technical field

The invention belongs to the technical field of optical fiber sensing, and in particular relates to a microsphere resonant filter integrated in a suspended core optical fiber for uploading/downloading filtering and physical quantity sensing and measurement.

Background technique

Microsphere resonators are spherical optical resonators with radii ranging from a few microns to hundreds of microns. Through continuous total reflection on the surface of the microsphere, the microsphere cavity confines the light near the equatorial plane and orbits along the great circle, stimulating a unique Whispering Gallery Mode (WGM or WG for short). Due to the effect of total reflection, the light field outside the sphere is an evanescent field. This light wave is a non-propagating wave, so the light that leaks out of the microsphere is extremely weak, so it can confine the light in a small volume for a long time. There is almost no loss, so the microsphere resonator has attracted much attention for its ability to store energy in a small volume for a long time. Optical microsphere cavities are widely used in optical integrated devices, optical filters, low-threshold laser emission, high-sensitivity sensors, optical communication devices and other fields due to their ultra-high quality factor (Q) and small mode volume.

How to efficiently excite the resonant modes in the microcavity is a problem to be solved in the practical application of the microsphere resonator. Prisms and integrated waveguide excitation methods have large device sizes and are not very efficient. The method of coupling the tapered fiber and the microsphere cavity can effectively couple light into/out of the microsphere cavity, excite high-Q resonance modes, and the coupling efficiency can reach more than 99%, so it is widely used by researchers. But how to keep the relative position of fiber cone and microsphere stable for a long time is the key to its effective application.

Contents of the invention

The object of the present invention is to provide a microsphere resonator filter integrated inside the suspended core optical fiber with firm package, compact size and strong anti-interference ability.

A microsphere resonator filter integrated in a suspended core fiber, including a suspended core fiber and microspheres, the suspended core fiber includes a cladding and a core, the cladding is a ring structure, the inside of the cladding is an air hole, and the cladding The inner diameter is 50-250 microns, the difference between the inner diameter and the outer diameter of the cladding is 20-40 microns, the fiber core is suspended on the inner wall of the cladding, the diameter of the fiber core is 9-13 microns, and the refractive index of the fiber core is greater than the direct refractive index of the cladding; The diameter of the microsphere is 50-200 microns, and the refractive index of the microsphere is greater than or equal to the refractive index of the fiber core. core alignment for direct coupling.

A microsphere resonator filter integrated in the suspended core optical fiber of the present invention may also include:

1. One or more fiber cores.

2. When there is one fiber core, the fiber core and microspheres are bonded by heating at the contact point between the fiber core and the microspheres.

3. When there are multiple fiber cores, the fiber core and the microspheres are bonded by heating and collapsing where the microspheres are located.

Beneficial effect:

1. The waveguide and microspheres are integrated inside the cladding glass tube by using the suspended core optical fiber. The filter device is tightly packaged, compact, highly integrated, and has strong anti-interference ability, suitable for long-term stable work;

2. The microsphere resonator filter is prepared by using the suspended core optical fiber, the manufacturing process is simple, the difficulty is low, and the repetition rate of the finished product is high;

3. The microsphere resonant filter can realize ordinary filters, and can also realize upload/download filters. Due to the existence of air holes, the device can realize the sensing and measurement of microfluidic solution or gas concentration.

Description of drawings

Figure 1 is a structural diagram of a microsphere resonator filter integrated inside a suspended single-core fiber;

Fig. 2 (a) is a cross-sectional schematic diagram of a suspended single-core optical fiber; Fig. 2 (b) is a schematic cross-sectional schematic diagram of a suspended multi-core optical fiber;

Fig. 3 is a schematic diagram of the preparation of the suspended single-core optical fiber core and the microsphere bonding and the alignment welding of the suspended single-core optical fiber and the single-mode optical fiber core;

Fig. 4 is a structural diagram of a microsphere resonant upload/download filter integrated inside a suspended dual-core optical fiber;

Fig. 5 is a schematic diagram of the preparation of the suspended dual-core optical fiber core and the microsphere bonding and the alignment welding of the suspended dual-core optical fiber and the single-mode optical fiber core;

Fig. 6 is the simulation result of the microsphere resonator filter inside the suspended single-core fiber.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

The invention uses a special suspended core optical fiber to encapsulate microspheres inside the optical fiber, and the suspended core optical fiber can effectively excite the resonant mode because the fiber core is exposed in the air. The filter device has a firm and compact package, is suitable for long-term stable work, and has a high production repetition rate.

The object of the present invention is to provide a microsphere resonator filter integrated in the suspended core optical fiber.

The object of the present invention is achieved as follows: a microsphere resonator filter integrated in the suspension core fiber is composed of a suspension core fiber 6 with a large air hole and a microsphere cavity 4 . Both ends of the suspended core optical fiber 6 are directly coupled with the single-mode optical fiber 7 by aligning the core; the microsphere 4 is firmly bonded to the core by local heating. The cladding 2 of the large air hole suspended core fiber 6 is a ring structure with an air hole 3 with a diameter of 50-250 microns in the center, and the thickness of the cladding ring is 20-40 microns. 13 microns, the core refractive index is greater than the cladding refractive index. The suspended core fiber can have a single core 1 or a plurality of cores 5-1 and 5-2. The diameter of the microsphere 4 is 50-200 microns, and the refractive index of the microsphere is greater than or equal to the refractive index of the fiber core. The core 1 of the suspended single-core optical fiber is bonded to the microsphere 4 by rotating the orientation of the fiber core to make the core 1 contact the microsphere 4, and then heat bonding at the contact point 8. The suspended multi-core optical fiber cores 5-1 and 5-2 are bonded to the microsphere 4 by heating and collapsing at the position 9 where the microsphere is located. The working principle of the microsphere resonator filter integrated in the suspended core fiber is that when the laser light source is coupled from the single-mode fiber to the suspended core fiber, the core of the suspended core fiber has a strong evanescent field because it is exposed in the air, so It can resonate with microspheres, and then realize microsphere resonant filters. Microsphere resonator filters based on multi-core fibers can also be used as upload/download filters. Due to the existence of air holes, the device can realize the sensing and measurement of microfluidic solution or gas concentration.

The invention provides a microsphere resonant filter integrated in the suspended core optical fiber, which is composed of a section of suspended single-core or multi-core optical fiber with large air holes and a microsphere cavity. The two ends of the suspended core fiber are directly coupled with the single-mode fiber through core alignment; the microspheres are firmly bonded to the core through local heating. Because the fiber core is exposed in the air, the suspended core fiber has a strong evanescent field, which can resonate with quartz microspheres, thereby realizing a microsphere resonant filter. Since the fiber core and the microspheres are inside the cladding glass tube, the filter device is firmly packaged, compact, highly integrated, and has strong anti-interference ability, and is suitable for long-term stable work; the device manufacturing repetition rate is high, and the manufacturing difficulty is reduced. At the same time, due to the existence of air holes, the device can realize sensing measurements such as microfluidic solution or gas concentration.

A microsphere resonant filter integrated in a suspended core fiber, the filter is composed of a section of suspended core fiber with a large air hole and a microsphere cavity. The two ends of the suspended core fiber are directly coupled with the single-mode fiber through core alignment; the microspheres are firmly bonded to the core through local heating.

The cladding of the large air hole suspended core fiber is a ring structure with an air hole with a diameter of 50-250 microns in the center. The thickness of the cladding ring is 20-40 microns. The core is suspended from the inner wall of the cladding. The core refractive index is greater than the cladding refractive index.

Large air hole suspended core fibers can have one or more cores.

The diameter of the microsphere is 50-200 microns, and the refractive index of the microsphere is greater than or equal to the refractive index of the fiber core.

The core of the suspended single-core optical fiber is bonded to the microsphere by rotating the orientation of the fiber core to make the core contact the microsphere, and then heat bonding at the contact point.

The core of the suspended multi-core optical fiber is bonded to the microsphere by heating and collapsing at the position of the microsphere.

The present invention is described in more detail below in conjunction with accompanying drawing example:

Example 1:

Referring to Fig. 1, Fig. 2(a), Fig. 3 and Fig. 6, a microsphere resonator filter integrated in a suspended single-core fiber is composed of a suspended core fiber 6 with a large air hole and a microsphere cavity 4. The core diameter of the suspended core fiber is 9 microns, and the diameter of the microsphere is 100 microns. The microsphere 4 can be sucked into the air hole under a certain air pressure, and the orientation of the single-core optical fiber is suspended by rotating, so that the core position is downward, and the microsphere is heated at the position 8 of the microsphere by arc discharge or hydrogen-oxygen flame, and the heating temperature is controlled. Without deforming the fiber, the microspheres can be firmly bonded to the fiber core. The two ends of the suspension core fiber 6 are aligned with the core of the single-mode fiber 7 by an arc welding machine, and are directly coupled; Strong evanescent field, so it can resonate with the microsphere, and then realize the microsphere resonant filter. Due to the existence of air holes, the device can realize the sensing and measurement of microfluidic solution or gas concentration. Fig. 6 is the result of a two-dimensional simulation experiment of the structure using the finite element method at a wavelength of 1.5 microns.

Example 2:

Referring to Fig. 2(b), Fig. 4 and Fig. 5, an upload/download filter integrated in a suspended multi-core fiber is composed of a suspended double-core fiber 6 with a large air hole and a microsphere cavity 4. The core diameter of the suspended core fiber is 10 microns, and the diameter of the microsphere is 150 microns. The microsphere 4 can be sucked into the air hole under a certain air pressure. By rotating and suspending the orientation of the double-core optical fiber, one fiber core is positioned downward, and the microsphere is heated by arc discharge or hydrogen-oxygen flame to control the heating temperature. The heating part 9 is collapsed, and the microspheres can be firmly bonded to the two fiber cores at the same time. The two cores 5-1 and 5-2 at both ends of the suspended double-core optical fiber 6 are aligned with the core of the single-mode optical fiber 7 by a welding machine, and directly coupled; when the laser light source is coupled from the single-mode optical fiber to the suspended double-core optical fiber Fiber core 5-1, the suspended core fiber core is exposed in the air and has a strong evanescent field, so it can resonate with the microspheres, thereby realizing the microsphere resonant filter, and the dual-core fiber core 5-2 It can achieve resonance with the microsphere at the upper contact point, so it can realize uploading and downloading filters.

Claims (4)

1. A microsphere resonator filter integrated in the inside of the suspended core optical fiber, characterized in that: comprise the suspended core optical fiber and the microsphere, the suspended core optical fiber comprises a cladding and a fiber core, the cladding is a ring structure, and the inside of the cladding is Air holes, the inner diameter of the cladding is 50-250 microns, the difference between the inner diameter and the outer diameter of the cladding is 20-40 microns, the core is suspended on the inner wall of the cladding, the diameter of the core is 9-13 microns, the refractive index of the core is Greater than the cladding direct radiation rate; the diameter of the microsphere is 50-200 microns, the refractive index of the microsphere is greater than or equal to the refractive index of the fiber core, the microsphere is located inside the cladding, the microsphere is bonded to the core through local heating, and the two ends of the core fiber are suspended Direct coupling to single-mode fiber with core alignment. 2. A microsphere resonator filter integrated in a suspended core fiber according to claim 1, characterized in that there are one or more fiber cores. 3. A kind of microsphere resonator filter integrated in the suspension core optical fiber according to claim 2, characterized in that: when the core is one, the bonding between the core and the microsphere is through the core and the microsphere The contact points of the microspheres are thermally bonded. 4. A microsphere resonator filter integrated in a suspended core optical fiber according to claim 2, characterized in that: when there are multiple cores, the bonding between the core and the microspheres is achieved through microspheres The location is heated and collapsed bonded.