CN101290377A - Light circulator based on space-free directional coupled structure - Google Patents

Abstract

The invention discloses an optical circulator based on a non-spacing directional coupling structure. The invention is formed by orderly and serially connecting an input Y-branch waveguide, a rectangular dual-mode waveguide provided with magnetic material, and an output Y-branch waveguide on a substrate. The proposal of the invention is to adopt the non-spacing directional coupling structure and utilize the non-reciprocal phase shift difference principle of a basic mode and a one-off pattern thereof to realize the integration of an optical isolator and the optical circulator through the non-reciprocal phase shift. The non-reciprocal device has the characteristics of compact structure and high integration level, has application prospect in aspects such as emission, amplification, transmission, and routing of light signals and so on, and has scientific research significance and application value.

Description

Based on continuously apart from the optical circulator of directional coupled structure

Technical field

The present invention relates to be used to control the device of direction of light, relate in particular to a kind of based on continuously apart from the optical circulator of directional coupled structure.

Background technology

In optical information systems such as optical fiber communication, the connection place of different components tends to antireflection part light, in case these reflected light enter the cavity of lasing light emitter, can make light source produce spurious oscillation, influence light source frequency stability, limit its modulation band-width, thereby the raising of restriction total system performance.Optoisolator (Optical Isolator) aims at the magneto-optic nonreciprocal device that addresses this problem and grow up.Up to the present, Shi Yong optoisolator has the micro-optical device that dwindles as the build optoisolator and the size of Faraday rotor with block garnet crystal.Yet, as integrated optics type optoisolator, still being in breadboard prototype conceptual phase so far, the device of practicability is not also developed.In addition, separate, make up different transmission route or multichannel wavelength signals and also need to use optical circulator (Optical Circulator).The same with optoisolator, the optical loop device is the device of the non-reversible transmission of another kind of realization light path.But optoisolator is that reverse transfer light is stopped, and the optical loop device is to the channeling conduct of reverse transfer light, itself and forward transmitted light are separated from the space, and from exporting with the another port, this specific character has great importance for the transmitted in both directions and the communication of light signal.Require lowly because the nonreciprocal optical device of waveguide type structure has magnetic field, cost is low, and volume is little, and loss is little, mechanical stability high and can with advantage such as other waveguide device compatibilities, so integrated optics type optoisolator and optical loop device have good prospects for application.

Summary of the invention

The object of the present invention is to provide a kind of optical circulator, utilize the nonreciprocal phase shift difference principle of its basic mode and one-off pattern, realize optoisolator or optical circulator based on the bimodulus principle of interference.

The technical solution adopted for the present invention to solve the technical problems is:

On substrate, form by the rectangular bimodule waveguide of importing y branch waveguide, have or be provided with magnetic material and output y branch waveguide serial connection successively.

The described length that has or be provided with the rectangular bimodule waveguide of magnetic material satisfies symmetric mode and anti symmetric mode constructive interference when forward transmitted, destructive interference during reverse transfer; Or symmetric mode and anti symmetric mode destructive interference when forward transmitted, constructive interference during reverse transfer.

Describedly be provided with magnetic material rectangular bimodule waveguide top surface center or the center is symmetrical arranged the magnetic material film.

Described have the waveguide of magnetic material rectangular bimodule by two-layer faraday's coefficient of rotary θ _FOpposite magnetic material film constitutes.

The beneficial effect that the present invention has is:

The present invention proposes to adopt continuously apart from the directional couple waveguiding structure, utilizes the nonreciprocal phase shift difference principle of its basic mode and one-off pattern, by nonreciprocal phase shift, realizes integrated optics type optoisolator and optical circulator.This nonreciprocal device has compact conformation, and the characteristics that integrated level is high have application prospect at aspects such as optical signal transmitting, amplification, transmission, routes, have scientific research meaning and using value.

Description of drawings

Fig. 1 structural principle synoptic diagram of the present invention.

Fig. 2 is provided with the rectangular bimodule waveguide cut-open view of magnetic material.

Fig. 3 has the rectangular bimodule waveguide cut-open view of magnetic material.

Among the figure: 1-imports y branch waveguide, the waveguide of 2-rectangular bimodule, and 3-exports y branch waveguide, 4-substrate, 5-magnetic material film, 6-overlayer.

Embodiment

Content of the present invention be relevant based on continuously apart from directional coupled structure, utilize the nonreciprocal phase shift difference principle of its basic mode and one-off pattern, realize optoisolator and optical circulator.

As shown in Figure 1, optoisolator of the present invention and optical circulator have utilized the image-forming principle of two-mode waveguide, by nonreciprocal phase shift, realize the non-reversible transmission of light path.Its structure by input y branch waveguide 1, have or be provided with the rectangular bimodule waveguide 2 and output y branch waveguide 3 serial connection of magnetic material, directly introduce the nonreciprocal phase shift district having or be provided with in the rectangular bimodule waveguide 2 of magnetic material.

According to the image-forming principle of two-mode waveguide, when a branch of polarized light after A port or the incident of B port, can evoke two patterns: basic mode and First-Order Mode, if see, can be used as symmetric mode and anti symmetric mode to them with the horizontal symmetry-line of rectangular bimodule waveguide.Symmetric mode and anti symmetric mode are concerned with, and when propagating in the two-mode waveguide district, mutual interference can take place for the two.Because there is propagation constant difference Δ β in these two mode propagation speed differences.If the length of rectangular bimodule waveguide is L, then relative phase difference

Suppose light from the input of A port, input optical power is P ₀, the luminous power P of output terminal _C, P _DCan be expressed as respectively

Choose suitable waveguide length L, the light that can realize forward transmitted is from the straight-through end or the end output that intersects.If relative phase difference is the even-multiple of π, symmetric mode and anti symmetric mode are in the terminal generation of rectangular bimodule wave guide zone constructive interference, and light is from the C port; If relative phase difference is the odd-multiple of π, symmetric mode and anti symmetric mode are in the terminal generation of rectangular bimodule wave guide zone destructive interference, and light is from the D port.

During reverse transfer, utilize the different principle of nonreciprocal phase shift difference of basic mode and one-off pattern, the nonreciprocal phase shift that magneto-optic memory technique produces is only to the basic mode effect, and it is very little to the influence of one-off pattern, so only need to be symmetrical arranged the magneto-optic memory technique district at the center or the edge in two-mode waveguide district, make symmetric mode and anti symmetric mode imaging law just opposite, export from intersecting to hold when holding the light reverse transfer of exporting from leading directly to forward transmitted.With the A port is example, and the length L of rectangular bimodule waveguide satisfies

$L=\mathrm{\π}\frac{2n}{{\mathrm{\β}}_{\mathrm{fw}}^e-{\mathrm{\β}}_{\mathrm{fw}}^o}=\mathrm{\π}\frac{2m+1}{{\mathrm{\β}}_{\mathrm{bw}}^e-{\mathrm{\β}}_{\mathrm{bw}}^o}$

β wherein _Fw ^e, β _Fw ^oThe propagation constant of symmetric mode and anti symmetric mode when being forward transmitted respectively, β _Bw ^e, β _Bw ^oThe propagation constant of symmetric mode and anti symmetric mode when being reverse transfer respectively, n, m are integer.Can realize exporting from the straight-through C of end from the light of A port input, from intersecting end B output, after reflecting, light positive is to transmitting from leading directly to end D output during the light reverse transfer, and after reflecting, the light reverse transfer holds A to export from intersecting, that is:

$A\⇒C\⇒B\⇒D\⇒A.$

When the length L of rectangular bimodule waveguide satisfies

$L=\mathrm{\π}\frac{2n+1}{{\mathrm{\β}}_{\mathrm{fw}}^e-{\mathrm{\β}}_{\mathrm{fw}}^o}=\mathrm{\π}\frac{2m}{{\mathrm{\β}}_{\mathrm{bw}}^e-{\mathrm{\β}}_{\mathrm{bw}}^o}$

Can realize $A\⇒D\⇒B\⇒C\⇒A,$ Thereby realize the capable function of the ring of light.

Utilize this structure can also realize the function that light is isolated, promptly $A\⇒C\⇒B$ Or $A\⇒D\⇒B.$

According to the material difference that is adopted, embodiments of the present invention can number of ways, can adopt Si, SiO as material ₂, semiconductor such as GaAs, polymeric material, LiNbO ₃, waveguide materials such as glass are made.

Embodiment 1:

On element manufacturing, employing on dielectric substrate, grow one deck nonmagnetic metal film or deielectric-coating, make the rectangular bimodule waveguide with wet chemical etching or reactive ion etching method again, adopting the method preparing centre (shown in Fig. 2 (a)) or the center symmetry (shown in Fig. 2 (b)) of local bonding or sputter that magnetic material film 5 is set above the rectangular bimodule wave guide zone again.

Embodiment 2:

Employing one deck magnetic material film of growing on substrate is made waveguide with wet chemical etching or reactive ion etching method again, also can go up the bigger overlayer 6 of face length one deck refractive index and substrate difference again, as shown in Figure 3.

In order to strengthen nonreciprocal phase shift, optoisolator that implementation structure is more compact and optical circulator can also adopt long again one deck faraday coefficient of rotary θ on the magnetic material film _FOpposite magnetic material film is made waveguide with wet chemical etching or reactive ion etching method again.Middle as shown in Figure 3 faraday's coefficient of rotary θ _F＞0 is positioned at faraday's coefficient of rotary θ _F＜0 top also can be with faraday's coefficient of rotary θ _F＜0 is arranged on faraday's coefficient of rotary θ _F＞0 below.

Claims (4)

1, a kind of based on continuously apart from the optical circulator of directional coupled structure, it is characterized in that: on substrate (4) successively by input y branch waveguide (1), have or be provided with the rectangular bimodule waveguide (2) of magnetic material and output y branch waveguide (3) and be connected in series and form.

2, according to claim 1 a kind of based on continuously apart from the optical circulator of directional coupled structure, it is characterized in that: the described length that has or be provided with the rectangular bimodule waveguide (2) of magnetic material satisfies symmetric mode and anti symmetric mode constructive interference when forward transmitted, destructive interference during reverse transfer; Or symmetric mode and anti symmetric mode destructive interference when forward transmitted, constructive interference during reverse transfer.

3, according to claim 1 a kind of based on continuously apart from the optical circulator of directional coupled structure, it is characterized in that: describedly be provided with magnetic material rectangular bimodule waveguide (2) upper surface center or the center is symmetrical arranged magnetic material film (5).

4, according to claim 1 a kind of based on continuously apart from the optical circulator of directional coupled structure, it is characterized in that: described have magnetic material rectangular bimodule waveguide (2) by two-layer faraday's coefficient of rotary θ _FOpposite magnetic material film (5) constitutes.

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