CN103744147A - Active optical cable optical coupling device with high coupling efficiency - Google Patents

Abstract

The invention discloses an active optical cable optical coupling device with high coupling efficiency. The active optical cable optical coupling device with the high coupling efficiency comprises a laser and an optical fiber, wherein a micro lens is installed between the laser and the coupling end of the optical fiber; the end surface of the coupling end of the optical fiber is a tapered plane; an included angle between the end surface of the coupling end of the optical fiber and the light emitting center line of the laser is 40-50 degrees; the end surface of the coupling end of the optical fiber is provided with a total reflection film; and the center of the end surface of the coupling end of the optical fiber and the center of the micro lens are positioned or almost positioned on the light emitting center line of the laser. According to the active optical cable optical coupling device with the high coupling efficiency, which is disclosed by the invention, the end surface of the coupling end of the optical fiber, which is in the tapered plane shape, is used, and the total reflection film is arranged, so that the active optical cable optical coupling device has a total reflection function to replace the reflection function of a prism in the traditional active optical cable optical coupling device. During engineering coupling, only the optical fiber or an optical fiber array needs to be coupled in two directions, the coupling difficulty is lowered, and the coupling efficiency is improved. The coupling efficiency can be 87.13% which is obviously higher than the coupling efficiency of the traditional active optical cable optical coupling device, which is below 80%, and the size of the whole device is reduced.

Description

The active optical cable optically coupled device of high coupling efficiency

Technical field

The present invention relates to a kind of active optical cable optically coupled device, more particularly to a kind of high coupling efficiency optically coupled device for being particularly suitable for use in 40G active optical cables.

Background technology

Broadband industry is developed rapidly, and laser communication repeater span is increasingly longer, traffic rate more and more higher, coupling efficiency has become one of its performance bottleneck.Active optical cable coupling efficiency especially under high-speed hardly results in guarantee, and OSNR (OSNR), dispersion, the coupling welding of nonlinear interaction and active optical cable internal components all govern coupling efficiency.

Current active optical cable, the coupling efficiency of its optical fiber and laser is relatively low, trace it to its cause is that optically coupled device design is not ideal enough, such as, the optically coupled device of current 40G active optical cables using it is more be VCSEL i.e. vertical cavity surface emitting laser and prism arrangement mode, concrete structure is as shown in Figure 1, the light that laser 1 is sent passes through 45 ° of prisms 2, light path changes after 90 °, is coupled with optical fiber 5, V-groove 3 and fiber entrance 4 are also show in Fig. 1.There is following defect in this structure：The signal that laser is sent is rotated by 90 ° light path by prism and enters optical fiber, need to move fiber array on four direction when optical signal is looked in coupling, it is difficult to Best Coupling position is found in the short time, so time and the human cost of debugging can be wasted, and also coupling efficiency is less than 80%.

Analyzed according to great mass of data, the peak transfer rate of fiber optic communication can be effectively improved by improving the coupling efficiency of optical fiber and laser, and the present invention is based on this theoretical and proposed.

The content of the invention

The purpose of the present invention is that to solve the above problems and provide a kind of active optical cable optically coupled device of high coupling efficiency.

The present invention is achieved through the following technical solutions above-mentioned purpose：

A kind of active optical cable optically coupled device of high coupling efficiency, including laser and optical fiber, lenticule is installed between the coupled end of the laser and the optical fiber, the coupled end end face of the optical fiber is tapered plane and is in 40 °~50 ° angles between the light extraction center line of the laser, the coupled end end face of the optical fiber is provided with total reflection film, and the center of the coupled end end face of the optical fiber and the lenticule are centrally located at or generally within the light extraction center line of the laser.

In said structure, laser is used to produce laser, and lenticule is used to focus on, and reflectivity is used in the fibre core in laser reflection to optical fiber close to 1 full transmitting film, and the application of wherein total reflection film makes the coupled end of optical fiber directly have laser reflection function；And the coupled end end face of optical fiber is tapered plane, make it in coupling, light source, reduction coupling difficulty need to be only found in the two directions.Full transmitting film is typically arranged at the coupled end end face of optical fiber using plating mode.

According to needs are applied, the laser, the lenticule and the optical fiber are multiple and arranged in parallel formation array structure.

Preferably, the coupled end end face of the optical fiber is tapered plane and is in 45 ° of angles between the light extraction center line of the laser.

Preferably, the lenticule is P planoconvex spotlights；The laser is the vertical cavity surface emitting laser that light emission side is provided with convex flat lenticule.

It is used as optimal selection, the index of refraction in lens of the lenticule is 1.46, lens radius is 60 μm, and radius of sphericity is 948.7 μm, and crown height is 1.9um, the focal length of lens is 2062.4um, lens thickness is 1000um, and the distance at lens focus to the lens plane end of the lenticule is 1440um, and focal radius is 32um, transmitance is 89.7%, and the distance between incident side front surface for going out flash ranging front surface and the optical fiber of the lenticule is 115.11um.

The beneficial effects of the present invention are：

The present invention uses the fiber coupling end end face of tapered plane shape and sets total reflection film, make it that directly there is reflection function, instead of the reflection function of prism in conventional active optical cable optically coupled device, when engineering is coupled, only optical fiber or fiber array need in the two directions be coupled, reduction coupling difficulty, improve coupling efficiency, it can reach 87.13%, hence it is evident that higher than coupling efficiency of the conventional active optical cable optically coupled device below 80%, add the optocoupler resultant in the unit interval；Due to eliminating prism, the purpose for being rotated by 90 ° light path is directly reached with optical fiber coupled end end face, so reducing the size of whole device, makes the present apparatus easily portable and saves installing space.

Brief description of the drawings

Fig. 1 is the structural representation of conventional active optical cable optically coupled device；

Fig. 2 is the structural representation of the active optical cable optically coupled device of high coupling efficiency of the present invention；

Fig. 3 is the A-A sectional views in Fig. 2；

Fig. 4 is the optic path schematic diagram of the active optical cable optically coupled device of high coupling efficiency of the present invention；

Fig. 5 is that schematic diagram is transmitted in the light reflection and anaclasis of the coupled end end face of optical fiber of the present invention；

Fig. 6 is impact analysis schematic diagram of the depth of parallelism to coupling efficiency of optical fiber incident side front surface of the present invention；

Fig. 7 is impact analysis schematic diagram of the mismachining tolerance to coupling efficiency of fiber coupling end of the present invention end face.

Embodiment

The invention will be further described below in conjunction with the accompanying drawings：

As shown in Figure 2, the active optical cable optically coupled device of high coupling efficiency of the present invention includes laser 7 and optical fiber 5, lenticule 6 is installed between the coupled end of laser 7 and optical fiber 5, the coupled end end face 52 of optical fiber 5 is tapered plane and is in 45 ° of angles between the light extraction center line of laser 7, can also be other angles beyond 45 ° between 40 °~50 °, the coupled end end face 52 of optical fiber 5 is provided with total reflection film (thickness very little, not shown in figure), the center of the coupled end end face 52 of optical fiber 5 and lenticule 6 are centrally located at or generally within the light extraction center line of laser 7.The fibre core 51 of optical fiber 5, laser transmission and reflection in fibre core 51 are shown in Fig. 2；The V-groove plate 3 for installation is also show in Fig. 2.

As shown in figure 3, laser 7, lenticule 6 and optical fiber 5 are multiple and arranged in parallel formation array structure, corresponding array is respectively laser array, microlens array and fiber array.

In this example, optical fiber 5 uses multimode light；Lenticule 6 uses P planoconvex spotlights；Laser 7 is provided with the vertical cavity surface emitting laser of convex flat lenticule 8 using light emission side；The index of refraction in lens of lenticule 6 is 1.46, lens radius is 60 μm, radius of sphericity is 948.7 μm, crown height is 1.9um, and the focal length of lens is 2062.4um, and lens thickness is 1000um, the lens focus of the lenticule to lens plane end distance be 1440um, focal radius is 32um, and transmitance is 89.7%, and the distance between incident side front surface for going out flash ranging front surface and optical fiber 5 of lenticule 6 is 115.11um.

The installation site of lenticule 6, coupling efficiency analysis in the active optical cable optically coupled device of high coupling efficiency of the present invention are described specifically below in conjunction with the accompanying drawings：

1st, lenticule 6 goes out determination of distance between flash ranging front surface and the incident side front surface of optical fiber 5：

As shown in figure 4, the light of light 1 and light 2 for the maximum angle of divergence of the light source 9 of laser 7,

α is expressed as with the surrounding layer of optical fiber 5 and the refraction angle on the surface of fibre core 51₁₂, α₂₂, α₁₃, α₂₃, incidence angle is expressed as α₁₁, α₂₁, when light 1 and light 2 reach end face 52, its angle of reflection is expressed as α₁, α₂；Light 3 is the central ray of the light source 9 of laser 7, and its incidence angle is expressed as α₃₁, α is expressed as with the surrounding layer of optical fiber 5 and the refraction angle on the surface of fibre core 51₃₂, α₃₃, when light 3 reaches end face 52, its angle of reflection is expressed as α₃。

Below equation is had according to Fig. 3：

n₀sinα₁₁=n₂sinα₁₂=n₁sinα₁₃

n₀sinα₂₁=n₁sinα₂₃=n₂sinα₂₂

n₀sinα₃₁=n₁sinα₃₃=n₂sinα₃₂

Wherein, n₀、n₁、n₂The refractive index of the fibre core of air refraction, the refractive index of the surrounding layer of optical fiber 5 and optical fiber 5 is represented respectively.

Result of calculation is：

α₁₁=α₂₁=10°；α₁₂=α₂₂=6.69 °；α₁₃=α₂₃=6.65°

Wherein, l_maxRepresent the distance between incident side front surface for going out flash ranging front surface and optical fiber 5 of lenticule 6.

Substitute into parameter calculating and obtain l_max=115.11um.

2nd, the fixed form design of lenticule 6：

Reference picture 2 and Fig. 3, when etching the V-groove of V-groove plate 3, the light input part of V-groove plate 3 under substrate is cut through (diameter for just reaching the array of discharge lenticule 6) according to the distance of lenticule 6 to optical fiber 5, retain non-light input part, V-groove plate 3 is fixed lenticule 6 while not falling apart.

The design ensure that the point of contact on the surface of optical fiber 5 only has three points, adds array and makes stability in engineering；Half block substrate is reduced, the cost in engineering is reduced；During coupling, only fiber array need to be inserted so that only find light source, reduction coupling difficulty in the two directions.

3rd, coupling efficiency is analyzed：

As shown in figure 4, incidence angle of the laser on the end face 52 of optical fiber 5 is with entering the refraction angle of optical fiber 5 from geometrical relationship：

α₁=45°+α₁₃

α₂=45°-α₂₃

α₃=45°-α₃₃

Wherein α₃For the angle of total reflection：

Can be calculated between light 2 and light 3 folded region is total reflection region, accounts for the beam ratio that lights of laser 7 and is：

The segment beam that lower surface analysis end face 52 is not totally reflected, the coupling efficiency of the refraction and reflection of end face 52：

As shown in Figure 4 and Figure 5：

Reflectivity calculation formula is met in media as well：

$R_S=\frac{{\sin }^2({\mathrm{\δ}}_1-{\mathrm{\δ}}_2)}{{\sin }^2({\mathrm{\δ}}_1+{\mathrm{\δ}}_2)}$

$R_p=\frac{{\tan }^2({\mathrm{\δ}}_1-{\mathrm{\δ}}_2)}{{\tan }^2({\mathrm{\δ}}_1+{\mathrm{\δ}}_2)}$

The reflectivity for obtaining the reflecting surface by above formula is：

The region not being totally reflected in end face 52, takes the average value of the region internal reflection rate as the reflectivity for not being totally reflected region：

$R({\mathrm{\α}}_2,{\mathrm{\α}}_3)=\frac{1}{{\mathrm{\α}}_3-{\mathrm{\α}}_2}\underset{{\mathrm{\α}}_2}{\overset{{\mathrm{\α}}_3}{\∫}}{R}_n\left({\mathrm{\δ}}_1\right)d{\mathrm{\δ}}_1$

It is then that the region light beam in the face of being all-trans accounts for the ratio of total light beam and is：

Then total coupling efficiency is：

Impact analysis of the depth of parallelism of the incident side front surface of optical fiber 5 to coupling efficiency is as follows：

As shown in fig. 6, coupling efficiency of the light beam after lenticule 6 with optical fiber 5Relational expression be：

It will be appreciated from fig. 6 that

Uprised as Δ α forward directions become big, reversely become big and diminish, and coupling efficiency is still maintained near 90% in ± 1 °, it can be said that bright, the parallelism error very little for entering flash ranging front surface of laser 7 and optical fiber 5.

Fig. 7 is schematic diagram of the present invention.

Impact analysis of the mismachining tolerance of fiber coupling end end face 52 to coupling efficiency is as follows：

As shown in fig. 7, Δ β can influence the result of calculation with β relational expressions, on other parameters be do not have it is influential.

Reflecting face error and Δ β and lenticule 6 and optical coupling efficiency can be obtained

Relational expression：

Analysis understands that Δ β is when inversely increasing, coupling efficiency

Reducing, when positive

As Δ β increases.During mapping, find when Δ β is at 3.2 °, i.e., β=48.2 ° when,

Effectively increase coupling efficiency.Therefore, the mismachining tolerance of fiber coupling end end face 52 can be conducive to the raising of coupling efficiency in positivity bias smaller angle.

Above-described embodiment is presently preferred embodiments of the present invention; it is not the limitation to technical solution of the present invention; as long as the technical scheme that can be realized without creative work on the basis of above-described embodiment, is regarded as falling into the rights protection scope of patent of the present invention.

Claims (6)

1. a kind of active optical cable optically coupled device of high coupling efficiency, including laser and optical fiber, it is characterised in that：Lenticule is installed between the coupled end of the laser and the optical fiber, the coupled end end face of the optical fiber is tapered plane and is in 40 °~50 ° angles between the light extraction center line of the laser, the coupled end end face of the optical fiber is provided with total reflection film, and the center of the coupled end end face of the optical fiber and the lenticule are centrally located at or generally within the light extraction center line of the laser.

2. the active optical cable optically coupled device of high coupling efficiency according to claim 1, it is characterised in that：The laser, the lenticule and the optical fiber are multiple and arranged in parallel formation array structure.

3. the active optical cable optically coupled device of high coupling efficiency according to claim 1, it is characterised in that：The coupled end end face of the optical fiber is tapered plane and is in 45 ° of angles between the light extraction center line of the laser.

4. the active optical cable optically coupled device of the high coupling efficiency according to claim 1,2 or 3, it is characterised in that：The lenticule is P planoconvex spotlights.

5. the active optical cable optically coupled device of the high coupling efficiency according to claim 1,2 or 3, it is characterised in that：The laser is the vertical cavity surface emitting laser that light emission side is provided with convex flat lenticule.

6. the active optical cable optically coupled device of the high coupling efficiency according to claim 1,2 or 3, it is characterised in that：The index of refraction in lens of the lenticule is 1.46, lens radius is 60 μm, radius of sphericity is 948.7 μm, crown height is 1.9um, and the focal length of lens is 2062.4um, and lens thickness is 1000um, the lens focus of the lenticule to lens plane end distance be 1440um, focal radius is 32um, and transmitance is 89.7%, and the distance between incident side front surface for going out flash ranging front surface and the optical fiber of the lenticule is 11511um.

Images