KR101432508B1 - Optical switch using reflection or refraction - Google Patents

Abstract

According to the optical switch using the reflection or refraction of the preferred embodiment of the present invention, when an index of refraction of a reflector is lower or higher than a waveguide, an optical switch capable of controlling the path of light by using refraction as well as reflection at the interface of the reflector .
The optical switch using the reflection of the preferred embodiment of the present invention includes: a main waveguide in which light enters and is in a linear shape; A branch waveguide branching at a predetermined angle from the main waveguide; And a reflector in which a refractive index is changed by application of a signal, wherein control is performed such that a second refractive index, which is a refractive index of the reflector, is smaller than a first refractive index, which is a refractive index of the main waveguide and the branch waveguide, Light is incident on a first interface in contact with the main waveguide of the reflector and is reflected to the outside of the reflector to induce light to the branch waveguide.

Description

OPTICAL SWITCH USING REFLECTION OR REFRACTION BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch using reflection or refraction, and more particularly, to an optical switch using reflection or refraction capable of changing a path of light using a change in refractive index of a reflector.

In the optical switching structure disclosed in Korean Patent Laid-Open No. 10-2010-0066834 (hereinafter referred to as 'the conventional invention'), a structure for controlling the reflection of a small angle and switching the path of the optical signal has been proposed. However, in the conventional invention, only a comprehensive reflection of light is considered in a reflector for reflecting light.

An object of the present invention is to solve the technical problem as described above, and it is an object of the present invention to provide a reflector capable of controlling the path of light by using refraction as well as refraction at the interface of the reflector when the refractive index of the reflector is lower or higher than that of the waveguide And an object thereof is to provide an optical switch using reflection or refraction.

According to a preferred embodiment of the present invention, there is provided an optical switch using reflection, comprising: a main waveguide in which light enters and is in a linear shape; A branch waveguide branching at a predetermined angle from the main waveguide; And a reflector in which a refractive index is changed by application of a signal, wherein control is performed such that a second refractive index, which is a refractive index of the reflector, is smaller than a first refractive index, which is a refractive index of the main waveguide and the branch waveguide, Light is incident on a first interface in contact with the main waveguide of the reflector and is reflected to the outside of the reflector to induce light to the branch waveguide.

According to another preferred embodiment of the present invention, there is provided an optical switch using reflection or refraction, comprising: a main waveguide in which light enters and is in a linear shape; A branch waveguide branching at a predetermined angle from the main waveguide; And a reflector in which a refractive index is changed by application of a signal, wherein a second refractive index, which is a refractive index of the reflector, is larger than a first refractive index, which is a refractive index of the main waveguide and the branch waveguide, The light enters into the reflector from the first interface in contact with the waveguide and then is incident on the second interface in contact with the main waveguide of the reflector and is reflected inside the reflector to induce light into the branch waveguide .

According to another preferred embodiment of the present invention, there is provided an optical switch using reflection or refraction, comprising: a main waveguide in which light enters and is in a straight line; A branch waveguide having a branch angle formed at a predetermined angle from the main waveguide and spaced apart from the main waveguide; And a reflector whose refractive index is changed by application of a signal, wherein the main waveguide and the branch waveguide are connected by the reflector.

According to another preferred embodiment of the present invention, there is provided an optical switch using reflection or refraction, comprising: a main waveguide in which light enters and is in a straight line; A branch waveguide branching at a predetermined angle from the main waveguide; And a reflector in which a refractive index is changed by application of a signal, wherein a second refractive index, which is a refractive index of the reflector, is controlled to be smaller than a first refractive index, which is a refractive index of the main waveguide and the branch waveguide, And enters into the reflector from the first interface in contact with the waveguide by refraction to induce light to the branch waveguide.

According to another preferred embodiment of the present invention, there is provided an optical switch using reflection or refraction, comprising: a main waveguide in which light enters and is in a straight line; A branch waveguide branching at a predetermined angle from the main waveguide; And a reflector in which a refractive index is changed by application of a signal, wherein a second refractive index, which is a refractive index of the reflector, is larger than a first refractive index, which is a refractive index of the main waveguide and the branch waveguide, And enters into the reflector from the first interface in contact with the waveguide by refraction to induce light to the branch waveguide.

According to the optical switch using the reflection or refraction of the preferred embodiment of the present invention, when an index of refraction of a reflector is lower or higher than a waveguide, an optical switch capable of controlling the path of light by using refraction as well as reflection at the interface of the reflector .

FIGS. 1A to 1C are explanatory diagrams of reflection or refraction of light when light is incident on a small medium in a medium having a large refractive index. FIG.
FIG. 2 is an explanatory view of the reflection or refraction of light when light is incident on a large medium in a medium having a small refractive index; FIG.
FIG. 3A is an optical switch using reflection or refraction according to the first embodiment of the present invention. FIG.
3B is an optical switch using reflection or refraction according to a second preferred embodiment of the present invention.
3C is an optical switch using reflection or refraction according to a third preferred embodiment of the present invention.
4A is an optical switch using reflection or refraction according to a fourth embodiment of the present invention.
4B is an optical switch using reflection or refraction according to a fifth preferred embodiment of the present invention.
4C is an optical switch using reflection or refraction according to a sixth embodiment of the present invention.
FIG. 4D is an optical switch using reflection or refraction according to a seventh preferred embodiment of the present invention. FIG.
4E is an optical switch using reflection or refraction according to an eighth embodiment of the present invention.
FIG. 4f is an optical switch using reflection or refraction according to a ninth embodiment of the present invention. FIG.
5A is an optical switch using reflection or refraction according to a tenth embodiment of the present invention.
5B is an optical switch using reflection or refraction according to an eleventh embodiment of the present invention.

Hereinafter, an optical switch using reflection or refraction according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It should be understood that the following embodiments of the present invention are only for embodying the present invention and do not limit or limit the scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

At the interface where the refractive index differs, the incidence of light is divided into internal incident and external incident. Inside the incident is a case where a refractive index of the incident medium at a high (n ₁₎ low medium (n _2), and if that is incident to, external incidence is a low refractive index medium (n ₂₎ high medium (n ₁₎ in the.

1A to 1C illustrate reflection or refraction of light when a light is incident on a medium having a large index of refraction, that is, when an internal incident occurs. FIG. 1A shows a case where the incident angle of light is smaller than a critical angle at which total internal reflection occurs, FIG. 1B shows a case where the incident angle is equal to the critical angle, and FIG. 1C shows a case where the incident angle is less than the critical angle.

In the case of internal incidence, the critical angle for reflection ([ theta] _c ) is given by: " (1) "

Here, n ₁ > n ₂ .

When the angle of incidence ( ? ₁ ) of light is larger than the critical angle ( ? _C ) ( ? ₁ > ? _C ), both internal reflection and internal refraction can occur as shown in FIG. In this case, the refracting angle ? ₂ is smaller than the incident angle ? ₁ ( ? ₂ < ? ₁ ). When the incident angle exceeds the critical angle, as shown in [Table 1], light is refracted and the transmittance transmitted through the interface is high, so that most of the light is refracted.

TE mode
θ _One ( n ₁ - n ₂ ) / n ₁ , ( n ₁ > n ₂ ) 0.0152 0.0038 0.0014 θ _c = 10 ° θ _c = 5 ° θ _c = 3 ° reflectivity Transmittance reflectivity Transmittance reflectivity Transmittance 3 ° One 0 One 0 One 0 4 ° One 0 One 0 0.042 0.958
(&amp;thetas; ₂ = 2.6 DEG) 5 ° One 0 One 0 0.012 0.988
(&amp;thetas; ₂ = 4.0 DEG) 10 ° One 0 0.005 0.995
(&amp;thetas; ₂ = 8.7 DEG) 0.001 0.999
(&amp;thetas; ₂ = 9.5 DEG) 15 ° 0.022 0.978
(&amp;thetas; ₂ = 11.2 DEG) 0.001 1,000
( [theta] ₂ = 14.2 [deg.]) 0.000 1,000
(&amp;thetas; ₂ = 14.7 DEG)

For example, in the case of (n ₁ - n ₂ ) / n ₁ = 0.0014, the critical angle θ _c = 3 °. Even if the incident angle θ ₁ = 4 °, the transmissivity is 0.958 and most of the light is refracted. In Table 1, transmission is simply calculated by the classical optical theory for TE (transverse mode) mode. The transmittance is defined as &quot; (2) &quot;

Here, I represents intensity of light, E represents electric field, subscript t represents transmission through refraction, and i represents incidence.

When the incident angle is equal to the critical angle ( θ ₁ = θ _c ), the refracted light is directed along the interface ( θ ₂ = 0), and the reflected light is symmetrically equal to the incident angle. In this case, a part of light is refracted and can not escape to the n ₂ medium, so that it can become a critical state of total reflection.

When the angle of incidence is smaller than the critical angle ( ? ₁ < ? _C ), as shown in FIG. 1C, all the light is internally reflected and total internal reflection occurs.

FIG. 2 shows a state in which light is reflected or refracted when light is incident on a large medium in a medium having a small refractive index, that is, in the case of an external incident.

As can be seen from FIG. 2, in the case of external incidence (n ₁ <n ₂ ), both external refraction and external refraction can occur at all incident angles. In this case, the refraction angle becomes smaller than the incident angle ( ? ₂ < ? ₁ ). When the refractive index difference is small and the incident angle is small, most of the light is externally refracted, as shown in Table 2 below. For example, (n ₁ - n ₂ ) / n ₁ = -0.0014, the transmissivity is 0.970 even at a small incident angle &amp;thetas; ₁ = 3 DEG, which indicates that most of the light is refracted. (n ₁ - n ₂ ) / n ₁ = -0.0152, the transmittance becomes 0.692 even at an incident angle of ? ₁ = 3 degrees, which indicates that more than half of the light is refracted.

TE mode
θ _One ( n ₁ - n ₂ ) / n ₁ , ( n ₁ < n ₂ ) -0.0152 -0.0038 -0.0014 reflectivity Transmittance reflectivity Transmittance reflectivity Transmittance 3 ° 0.308 0.692
(&amp;thetas; ₂ = 10.4 DEG) 0.103 0.897
(&amp;thetas; ₂ = 5.8 DEG) 0.030 0.970
(&amp;thetas; ₂ = 4.3 DEG) 4 ° 0.211 0.789
(&amp;thetas; ₂ = 10.7 DEG) 0.053 0.947
(&amp;thetas; ₂ = 6.4 DEG) 0.013 0.987
( [theta] ₂ = 5.0 [deg.]) 5 ° 0.147 0.853
( [theta] ₂ = 11.1 [deg.]) 0.030 0.970
(&amp;thetas; ₂ = 7.6 DEG) 0.006 0.994
(&amp;thetas; ₂ = 5.8 DEG) 10 ° 0.030 0.970
(&amp;thetas; ₂ = 14.1 DEG) 0.003 0.997
(&amp;thetas; ₂ = 11.2 DEG) 0.000 1,000
(&amp;thetas; ₂ = 10.4 DEG) 15 ° 0.009 0.991
(&amp;thetas; ₂ = 17.9 DEG) 0.001 0.999
(&amp;thetas; ₂ = 15.8 DEG) 0.000 1,000
(&amp;thetas; ₂ = 15.3 DEG)

Taking all the tendencies as described above, if the angle of incidence is small at a small refractive index difference, most of the light can be reflected or refracted in one direction. Using this, the optical path can be switched in various structures as in the embodiments of the present invention.

First, FIG. 3A shows an optical switch 100 using reflection or refraction according to a first preferred embodiment of the present invention.

3A, the optical switch 100 using reflection or refraction according to the first preferred embodiment of the present invention includes a main waveguide 110, a main waveguide 110, A branch waveguide 120 which forms a branch angle ? _{B at a} predetermined angle from the reflector 110 and a reflector 130 whose refractive index is changed by application of a signal.

In the optical switch 100 of the first embodiment of the present invention, the first refractive index n ₁ , which is the refractive index of the main waveguide 110 and the branch waveguide 120, n _r ) is small. In the optical switch 100 of the first embodiment of the present invention, the reflector 130 is arranged at a first interface (the line connecting the points b and c in FIG. 3A) in contact with the main waveguide 110 from the main waveguide 110, And 131, and reflects the light to the outside of the reflector 130, thereby guiding light to the branch waveguide 120.

In the optical switch 100 of the first embodiment of the present invention, the first reflector angle ? _R formed by the main waveguide 110 and the first interface 131 is larger than the first interface 131 and the reflector 130 ) Is equal to an angle ( ? ₁ ) formed by light reflected from the outside. In addition, the first interface 131 of the reflector 130 may include a first vertex 131 located at an upper one of the first vertex b and the second vertex a that the main waveguide 110 and the branch waveguide 120 meet, (b). It is also preferable that the branch angle ? _B is substantially equal to or the same as the first reflector angle ? _R.

), 보다 작게 만들 경우(θ _r ≤ θ _c), 입사각(θ ₁ = θ _r )은 임계각(θ _c) 보다 작게 되므로 내부 전반사를 얻을 수 있다. 내부 전반사가 일어난 빛은 가지 도파로(120)로 들어가게 된다. 반사기(130)의 굴절률을 주위 도파로(110, 120)의 굴절률과 거의 같도록 제어하면(n_r ~ n₁), 반사를 겪지 않고 반사기(130) 부분을 통과하여 주 도파로(110)로 직진하게 된다. 여기서 빛이 반사기(130) 부분을 통과하여 주 도파로(110)로 직진하는 상태를 ‘통과 상태(pass state)’로 표현하고, 빛이 반사기(130)에서 반사되어 가지 도파로(120)로 유도되는 상태를‘반사 상태(reflection state)’로 표현한다. 이와 같이, 반사기(130)의 굴절률을 적절히 제어하여, 이들 ‘통과 상태’와 ‘반사 상태’의 두 가지 상태로 전환시킴으로써 광 경로를 스위칭(path switching)시킬 수 있고, 주 도파로(110)와 가지 도파로(120) 중 하나의 도파로를 지나가는 광신호의 세기를 디지털 신호로 변조(modulation) 시킬 수도 있다.
More specifically, the operation of the optical switch 100 of the first embodiment of the present invention in Fig. 3A will be described. The incident light may be internally reflected at the first interface 131 of the reflector 130 and the angle ? _R of the first interface 131 of the reflector 130 may be set at a critical angle ( ? _c ,

( Θ _r = θ _c ), the incident angle θ ₁ = θ _r becomes smaller than the critical angle θ _c , so that the total internal reflection can be obtained. The light having the total internal reflection enters the branch waveguide 120. The refractive index of the reflector 130 is controlled so as to be substantially equal to the refractive index of the surrounding waveguides 110 and 120 (n _r to n ₁ ), the light passes through the reflector 130 without going through the reflector and travels straight to the main waveguide 110 do. Here, a state in which light passes through the reflector 130 and goes straight to the main waveguide 110 is expressed as a 'pass state', and light is reflected by the reflector 130 and is guided to the branch waveguide 120 State as a 'reflection state'. In this way, the optical path can be switched by switching the refractive index of the reflector 130 to the two states of 'pass state' and 'reflection state' by appropriately controlling the refractive index, The intensity of the optical signal passing through one waveguide of the waveguide 120 may be modulated into a digital signal.

3A, light entering the branch waveguide 120 is incident on the right side interface of the branch waveguide 120 at an angle of ? ₁ 'to ? ₁ , and the refractive index difference n _clad -n ₁ is greater than the refractive index difference n _r -n ₁ at the first interface 131 of the reflector 130 so that the total internal reflection condition can be satisfied at the branch waveguide 120 interface, The light can be guided into the light guide 120. Where n _clad is the refractive index of the clad surrounding the branch waveguide 120. However, in the optical switch 100 of the first embodiment of FIG. 3A, loss due to scattering of light may be caused by colliding with the angle of ? ₁ 'to ? ₁ at the interface of the branch waveguide 120.

As a more preferable embodiment in which scattering of light at the branch waveguide 220 interface can be reduced, an optical switch 200 using the reflection or refraction of the second embodiment as shown in FIG. 3B is proposed.

3B, the optical switch 200 according to the second embodiment of the present invention is configured such that the branch angle ? _B formed by the main waveguide 210 and branch waveguide 220 is smaller than the angle of the reflector interface 231 which it was twice as close to the first reflector angle (θ _r). When a ~ θ _b 2 θ _r is because the reflected light proceeds in the same direction as the branch waveguide 220, branch waveguide can reduce the scattering of light in the 220.

That is, the optical switch 200 of the second embodiment of the present invention is characterized in that the branch angle ? _B is larger than the first reflector angle ? _R.

3C shows an optical switch 300 using reflection or refraction according to a third preferred embodiment of the present invention.

In the optical switch 300 using reflection or refraction according to the third preferred embodiment of the present invention shown in FIG. 3C, although the branch angle ? _B is larger than twice the first reflector angle ? _R ( ? _B > 2 &amp;thetas; _r ), it is possible to induce light into the branch waveguide 320. [

보다 작으면(θ ₁″< θ _wc), 가지 도파로(320) 내에서 전반사에 의한 유도가 가능하다. 예로서 주 도파로(310) 또는 가지 도파로(320)에 실리콘(silicon) 재료를 사용하고(n₁ ~ 3.5), 클래드가 SiO₂ 공기(n_clad ~ 1.5)인 경우에 가지 도파로(320) 계면의 임계각은 ~64°가 되어, 이론적으로는 매우 큰 각도로의 경로 변경이 가능하다. 따라서, 작은 각도의 내부 반사를 이용할 경우에 가지 각도(θ _b)를 제 1 반사기 각도(θ _r) 보다 훨씬 크게 만들 수 있는 특징이 있다.
When θ _b > 2 θ _r , the light reflected internally at the reflector interface 331 is incident on the left interface of the branch waveguide 320 at an angle θ ₁ "as shown in FIG. 3C. This & quot ;? ₁ &quot; is the critical angle at the interface of the branch waveguide 320

(&Amp;thetas; ₁ &quot; &amp;thetas; _wc ), it is possible to induce total reflection within the branch waveguide 320. [ For example, a silicon material is used for the main waveguide 310 or branch waveguide 320 (n ₁ ~ 3.5) and the clad is SiO ₂ air (n _clad ~ 1.5), the critical angle of the interface of the branch waveguide 320 becomes ~ 64 °, theoretically it is possible to change the path to a very large angle. Therefore, there is a feature that the branch angle ? _B can be made much larger than the first reflector angle ? _R when a small angle of internal reflection is used.

4A to 4F are embodiments in which the reflectance of the reflector n _r is greater than the refractive index n ₁ of the surrounding waveguide to implement the optical path change. That is, when n _r > n ₁ as in FIGS. 4A to 4F, the first interfaces 431, 531, 631, 731, 831, and 931 of the reflectors 430, 530, 630, 730, 830, Refraction occurs and, when the incident angle is small, most of the light is refracted and enters the reflectors 430, 530, 630, 730, 830, and 930 as shown in [Table 2].

4A shows an optical switch 400 using reflection or refraction according to a fourth preferred embodiment of the present invention.

4A, the optical switch 400 according to the fourth embodiment of the present invention includes a main waveguide 410 in which light is incident and a straight line shape, a branch waveguide 410 having a branch angle ? _B The optical switches 100, 200 and 300 of the first to third embodiments are different from the optical switches 100, 200 and 300 of the first to third embodiments in that the branch waveguide 420 in the form of a branch and the reflector 430 in which the refractive index is changed by application of a signal same.

However, the optical switch 400 of the fourth embodiment of FIG. 4A has the following features. That is, the second refractive index n _r , which is the refractive index of the reflector 430, is controlled to be larger than the first refractive index n ₁ , which is the refractive index of the main waveguide 410 and the branch waveguide 420, The light enters the reflector 430 through the first interface 431 in contact with the waveguide 410 and then enters the second interface 432 in contact with the main waveguide 410 of the reflector 430, The light is guided to the branch waveguide 420 by being reflected inside the branch waveguide 430.

In the optical switch 400 of the fourth embodiment of the present invention, the angle ? ₂ 'formed by the light incident on the second interface 432 with the second interface 432 is greater than the critical angle of the second interface 432 If it is smaller than ? _c2 , total reflection takes place inside the reflector 430. [ In the optical switch 400 according to the fourth embodiment of the present invention, both the first interface 431 and the second interface 432 have the first corner 431 and the second corner 432, which are formed by the main waveguide 410 and the branch waveguide 420, (b) and the second vertex (a), or between the first vertex (b) and the second vertex (a).

, (θ ₂′ ≤ θ _c2))을 만족하면, 전반사에 의해 가지 도파로(420)로 빛을 유도할 수 있다. 가지 도파로(420)의 구경 너비 a-b를 반사기(430)의 구경 너비 c-d와 같거나 크게 하면, 제 2 계면(432)에서 전반사된 빛은 높은 효율로 가지 도파로(420)로 유도할 수 있다. 이 구조에서도 아래쪽 a-c 간격을 크게 하면, 반사기(430)의 제 1 계면(431)에서 일부 반사된 빛을 가지 도파로(420) 안으로 유도할 수 있어, 가지 도파로(420)로 들어가는 빛의 양을 더 높일 수 있다.
That is, the optical switch 400 of the fourth embodiment of the present invention internally reflects the light refracted at the first interface 431 of the reflector 430 at the second interface 432, . At the second interface 432, the incident angle ? ₂ '

, If any of the ₍₂ θ '≤ θ _c2)), can lead to light of a waveguide 420 by total reflection. If the aperture width ab of the branch waveguide 420 is equal to or larger than the aperture width cd of the reflector 430, the light totally reflected at the second interface 432 can be guided to the branch waveguide 420 with high efficiency. Also in this structure, if the lower ac spacing is increased, light partially reflected at the first interface 431 of the reflector 430 can be guided into the branch waveguide 420, and the amount of light entering the branch waveguide 420 can be increased .

4B shows an optical switch 500 using reflection or refraction according to a fifth preferred embodiment of the present invention. The optical switch 500 of the fifth embodiment in Fig. 4B is the same as the optical switch 400 in the fourth embodiment except that one end of the first interface 531 is connected to one end of the second interface 532 The third interface 533 of the reflector 530 which is one of the surfaces of the main waveguide 510 is in contact with one surface of the main waveguide 510 that is in contact with the branch waveguide 520 among two surfaces in the longitudinal direction.

That is, in order to simplify the shape of the reflector 530, the optical switch 500 of the fifth embodiment of the present invention has a structure in which the aperture cd of the reflector 530 is made oblique to the interface direction of the main waveguide 510. The first interface 531 of the reflector 530 is adjusted by appropriately adjusting the first reflector angle ? _R , the branch angle ? _B , the aperture width cd of the reflector 530 and the aperture width ab of the branch waveguide 520, The light reflected or refracted at the second interface 532 or the light reflected at the second interface 532 can be transmitted to the waveguide 520 as much as possible.

4C shows an optical switch 600 using reflection or refraction according to a sixth preferred embodiment of the present invention. In the structure of the optical switch 500 according to the fifth embodiment of the present invention, the aperture cd of the reflector 530 is deviated at a sharp angle so that the refraction angle of light at the interface 533 sensitively changes, There may be a problem of entering into. In order to prevent such a problem, the aperture cd of the reflector 630 may be made to have a dull angle as shown in FIG. 4C.

4D shows an optical switch 700 using reflection or refraction according to a seventh preferred embodiment of the present invention. The seventh embodiment the optical switch 700 of the present invention Fig. 4d, the fifth embodiment of the optical switch 500 and the other points are the same, the fifth embodiment of the optical switch 500 of the angle (θ _b) is the main waveguide 510 and the second interface (532) and forms a second reflector angle (θ _r ') with the other hand, the seventh embodiment of the optical switch 700 of the angle (θ _b) having a value equal to the main waveguide ( 7 'and a second reflector angle ? _R ' between the second interface 710 and the second interface 732. This structure is possible because the critical angle ? _Wc of the branch waveguide 720 is generally larger than the critical angle ? _C 'of the reflector 730 as shown in FIG. 3c ( ? _Wc >> ? _c '). Thus, different even if the angle (θ _b) of the waveguide 720 is large, the light reflected at the second interface 732 of the reflector 730 enters one end of the waveguide 720, θ ₂ "<θ _wc of The light satisfying the condition can be propagated to the branch waveguide 720 by total internal reflection. The angle ? _B of the branch waveguide 720 can be increased to the range satisfying ? ₂ "< ? _Wc .

4E shows an optical switch 800 using reflection or refraction according to an eighth embodiment of the present invention.

4E, the optical switch 800 according to the eighth preferred embodiment of the present invention includes a main waveguide 810 in which light enters and is in a linear shape, a branch waveguide 810 having a branch angle ? _B A branch waveguide 820 which is separated from the main waveguide 810 and a reflector 830 whose refractive index is changed by application of a signal. That is, the optical switch 800 of the eighth embodiment of the present invention is characterized in that the main waveguide 810 and the branch waveguide 820 are connected by a reflector 830.

However, controlling the second refractive index n _r , which is the refractive index of the reflector 830, to be larger than the first refractive index n ₁ , which is the refractive index of the main waveguide 810 and branch waveguide 820, Are the same as the optical switches (400, 500, 600, 700) of the embodiments to the seventh embodiment.

Specifically, in the optical switch 800 of the eighth preferred embodiment of the present invention, light is incident into the reflector 830 by refraction from the first interface 831 in contact with the main waveguide 810 of the reflector 830 The light is incident on the second interface 832 in contact with the main waveguide 810 of the reflector 830 and is reflected inside the reflector 830 to induce light to the branch waveguide 820. The second reflector angle ? _R 'formed by the main waveguide 810 and the second interface 832 is greater than the branch angle ? _B.

That is, when the branch angle ? _B is small, the coupling between the main waveguide 810 and the branch waveguide 820 increases when the refractive index of the reflector 830 does not change (n _r to n ₁ ) A part of the light traveling straight ahead may leak into the branch waveguide 820. [ As a preferable method for reducing this problem, a gap is formed between the branch waveguide 820 and the main waveguide 810, that is, between the point d and the point e, The structure for connecting to the waveguide 820 is the optical switch 800 of the eighth embodiment of the present invention.

The optical switches 400, 500, 600, 700, and 800 of the fourth through eighth embodiments of the present invention using external refraction are all arranged at the first interface 431 of the reflectors 430, 530, 630, 730, 531, 631, 731 and 831 and the incident angle at the second interfaces 432, 532, 632, 732 and 832 is greater than the incident angle of the first interfaces 431, 531, 631, 731 and 831 ( ? ₂ '& lt ;? ₁ ). Thus, in order to obtain total internal reflection at the second interfaces 432, 532, 632, 732 and 832, the total internal reflection is used at the first interfaces 131, 231 and 331 as in the first to third embodiments There is a drawback that the angle of the reflectors 430, 530, 630, 730, and 830 must be made smaller.

In order to solve the above-mentioned problems, an optical switch 900 of the ninth embodiment of the present invention shown in Fig. 4F is proposed. As a ninth embodiment of the optical switch 900 of the present invention, by giving made of a vertical or greater angle, the first interface gh (931) of the reflector 930 to the main waveguide 910, greatly make the angle of incidence (θ ₁₎ . That is, if the incident angle ? ₁ at the first interface 931 is increased to be close to a right angle, the light proceeds almost linearly and the transmittance can be increased close to 1. Therefore, in the case of using the reflector 930 with n _r > n ₁ , it is preferable that the second interface 932 of the reflector 930 is made at a small angle and the first interface 931 is made at a large angle .

That is, in the optical switch 900 of the ninth embodiment of the present invention, the angle ? ₁ formed by the light incident on the first interface 931 with the first interface 931 is smaller than the angle ? And one light is larger than the angle formed by the second interface 932. More preferably, the angle ? ₁ between the light incident on the first interface 931 and the first interface 931 is a right angle.

5A shows an optical switch 1000 using reflection or refraction according to a tenth embodiment of the present invention.

According to [Table 1] and [Table 2], when a refraction occurs at a small incident angle, most light is transmitted irrespective of internal refraction or external refraction. Using this characteristic, as in the tenth embodiment of the present invention, it is possible to provide the direct entrance 1030 of the light refracted at the first interface 1031 of the reflector 1030 to the waveguide 1020, Lt; RTI ID = 0.0 &gt; 1031 < / RTI &gt; When the first reflector angle (θ _r) is larger than the critical angle (θ _c), (θ _r ≥ θ _c), as shown in Table 1, most of the light is the internal refraction at the first surface 1031. If the first reflector angle ? _R is provided so that the refraction angle ? ₂ becomes ? ₂ < ? _2max , the light refracted at the first interface 1031 of the reflector 1030 can be directly introduced into the branch waveguide 1020 have. Here, θ _2max is the diameter of the light of the waveguide 1020, which proceeds to the center of the main waveguide (1010) (aperture), the maximum refraction angle that ab can get inside. This structure has a problem θ ₂ is not easily susceptible to a condition of θ ₂ Fit <θ _2max to θ _1. This problem can be solved by enlarging the aperture width ab of the branch waveguide 1020 and the aperture width cd of the reflector 1030. That is, if the wider the ab and cd, it is also possible to increase the range of θ ₂ θ _2max which can enter into the larger of the waveguide 1020. If the difference in width between the branch waveguide 1020 and the reflector 1030 is increased and the distance between the lower ac is increased, the light partially reflected at the first interface 1031 of the reflector 1030 is guided into the waveguide 1020 So that the amount of light entering the branch waveguide 1020 can be further increased. As described above, the coupling efficiency of light entering the branch waveguide 1020 can be controlled by appropriately adjusting the interval between the aperture width cd of the reflector 1030 and the aperture width ab of the branch waveguide 1020.

5B shows an optical switch 1100 using reflection or refraction according to an eleventh embodiment of the present invention.

The optical switch 1100 of the eleventh embodiment of Figure 5b provides a reflector 1130 with a refractive index n _r that is higher than the ambient n ₁ and reflects an external refraction at the first interface 1131 of the reflector 1130 Fig. 5 shows an example of the optical path changing structure using the optical path changing structure. In the case of external refraction, as shown in Table 2, most of the light is transmitted at the first interface 1131 unless the incident angle is very small. When external refraction occurs, the branch waveguide 1120 is disposed on the left side of the main waveguide 1110 because the refraction angle ? ₂ is larger than the incident angle ? ₁ ( ? ₂ > ? ₁ ). This point is significantly different from the case of using the internal refraction ( ? ₂ < ? ₁ ) of FIG. 5A in which the branch waveguide 1120 is disposed on the right side of the main waveguide 1110. In order to sufficiently guide the refracted light to the waveguide 1120, it is necessary to allow the first interface 1131 of the reflector 1130 to enter the aperture width ab of the branch waveguide 1120 and to set the refraction angle ? ₂ to be larger than ? _2min ( ? ₂ > ? _2min ) is preferable. Where θ _2min is the diameter of the light traveling in the center of the main waveguide (1110) of the waveguide (1120) (aperture) it is ab minimum refractive angle that can get inside. The position and angle of the second interface of the reflector 1130 (the interface at which the point d lies) 1132 is properly set so that the internally refracted light at this second interface 1132 can enter the aperture width ab of the branch waveguide 1120 do.

In summary, the optical switch 1100 according to the eleventh preferred embodiment of the present invention includes a main waveguide 1110 in which light is incident and linear, a branch waveguide 1110 having a branch angle formed at a predetermined angle from the main waveguide 1110, A reflector 1120 and a reflector 1130 whose refractive index is changed by application of a signal. The optical switch according to the eleventh embodiment of the present invention preferably has a refractive index of the second reflector 1130 that is smaller than the refractive index n ₁ of the main waveguide 1110 and the branch waveguide 1120, The refractive index n _r is controlled to be large so that the light is incident from the main waveguide 1110 to the inside of the reflector 1130 through the first interface 1131 in contact with the main waveguide 1110 of the reflector 1130, (1120). &Lt; / RTI &gt; More specifically, the angle formed by the light incident upon the first interface 1131 and the reflector 1130 by the refraction is smaller than the angle ( ? ₁ ) between the light incident from the main waveguide 1110 and the first interface 1131 Since θ ₂₎ is further larger, the location of the waveguide 1120 is preferably located in an oblique direction opposite to the side of the first surface 1131 of the reflector.

For reference, the change in refractive index in a material is caused by an electro-optic effect, an electroabsorption effect, a carrier-doping effect by plasma dispersion of electrons and holes, optic effect, acousto-optic effect, nonlinear effect, surface plasmonic effect, and the like, but most of them can be obtained by using various effects such as doping effect, thermo-optic effect, In materials, the change in refractive index due to these effects is very small, less than 0.01. When the refractive index change (n ₁ - n ₂ ) / n ₁ is very small, the critical angle is reduced to several degrees (°).

For example, in the case of a silicon semiconductor material, when a p-type or n-type impurity is doped, the refractive index becomes lower than the intrinsic state by carriers of electrons and holes. The effect is that the theoretical refractive index in the range of acceptor and donor concentrations in the range of 5 x 10 ¹⁷ to 1 x 10 ²⁰ is less than 5 x 10 ^-4 Lt; ^-1 &gt; ^-1 . Namely, the refractive index difference between the doped state and the intrinsic state is in the range of -n = n ₁ - n ₂ in the range of -0.0005 to -0.1, and (n ₁ - n ₂ ) / n ₁ is in the range of -0.00015 to -0.03 . In the above-mentioned refractive index range, the critical angle is in the range of 1 to 15 degrees. The change in the refractive index due to the electric field or doping does not significantly exceed the refractive index change range described above. Considering the range of change in the refractive index that can be obtained with an electric field in a generally usable material, the critical angle is reduced to within a range of 20 degrees. Therefore, in the present invention, the reflection of a small angle means reflection within a range of 20 °, in which the total reflection can be obtained practically due to a change in refractive index. The present invention utilizes the principle that the light path can be changed to a small total reflection angle in the above-described range with a small refractive index change in the above-mentioned range.

Further, the reflector of the present invention can be used as a reflector having an electro-optic effect, an electroabsorption effect, a carrier doping effect by plasma dispersion of electrons and holes, optic effect, a nonlinear effect, a surface plasmonic effect, or the like, which can change the refractive index of a material, for example, a doping effect, a thermo-optic effect, an acousto-optic effect, .

In this case, an electrode capable of applying an electric field or current (or carrier) is provided in the vicinity of the waveguide, so that the refractive index (refractive index) of the reflector A controller having a control function can be used to control the refractive index of the reflector. A nonlinear effect, a surface plasmon effect, or the like may be used to provide a reflector that uses light as a control signal because the refractive index may be changed not only by electrical but also by light. The electric control signal or the optical control signal is generated in the controller and sent to the reflector to change the refractive index of the reflector.

As described above, according to the optical switch using the reflection or refraction of the preferred embodiment of the present invention, when the refractive index of the reflector is lower or higher than the waveguide, the path of the light is controlled by using refraction at the interface of the reflector It is possible to provide an optical switch.

100: An optical switch according to the first embodiment of the present invention
200: An optical switch according to the second embodiment of the present invention
300: An optical switch according to the third embodiment of the present invention
400: An optical switch according to the fourth embodiment of the present invention
500: An optical switch according to the fifth embodiment of the present invention
600: An optical switch according to the sixth embodiment of the present invention
700: An optical switch according to the seventh embodiment of the present invention
800: An optical switch according to the eighth embodiment of the present invention
900: An optical switch according to the eighth embodiment of the present invention
1000: An optical switch according to the tenth embodiment of the present invention
1100: An optical switch according to the eleventh embodiment of the present invention
110, 210, 310, 410, 510, 610, 710, 810, 910, 1010, 1110:
120, 220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120:
130, 230, 330, 430, 530, 630, 730, 830, 930, 1030,
131, 231, 331, 431, 531, 631, 731, 831, 931, 1031, 1131:
132, 232, 332, 432, 532, 632, 732, 832, 932, 1032, 1132:

Claims (19)

A main waveguide in which light enters and is in a straight line;
A branch waveguide branching at a predetermined angle from the main waveguide; And
A reflector in which a refractive index is changed by at least one of an electro-optic effect, an electroabsorption effect, and a carrier-doping effect upon application of a signal,
And a second refractive index that is a refractive index of the reflector is smaller than a first refractive index that is a refractive index of the main waveguide and the branch waveguide so that light is incident on the first interface in contact with the main waveguide of the reflector from the main waveguide And then the light is totally reflected to the outside of the reflector to induce light into the branch waveguide,
Wherein the critical angle of total reflection is within 20 degrees from an incident angle of light. The method according to claim 1,
Wherein the first interface of the reflector meets the first vertex located at the upper one of the first vertex and the second vertex that the main waveguide meets with the branch waveguide or is located at a position between the first vertex and the second vertex, The optical switch comprising: The method according to claim 1,
Wherein the branch angle is greater than or equal to a first reflector angle formed between the main waveguide and the first interface. A main waveguide in which light enters and is in a straight line;
A branch waveguide branching at a predetermined angle from the main waveguide; And
And a reflector whose refractive index is changed by application of a signal,
And a second refractive index that is a refractive index of the reflector is larger than a first refractive index that is a refractive index of the main waveguide and the branch waveguide, And the light is incident on the second interface, which is in contact with the main waveguide of the reflector, and is reflected inside the reflector, thereby guiding light to the branch waveguide. 5. The method of claim 4,
Wherein an angle formed by the light incident on the second interface with the second interface is equal to or smaller than a value obtained by taking an inverse function of a cosine after dividing the first refractive index by the second refractive index. switch. 5. The method of claim 4,
Wherein the first interface and the second interface both meet a first vertex and a second vertex that the main waveguide and the branch waveguide meet and pass between the first vertex and the second vertex, Or optical switch using refraction. 5. The method of claim 4,
The third interface of the reflector which is one of the surfaces connecting one end of the first interface and one end of the second interface is in contact with one of the two longitudinal surfaces of the main waveguide in contact with the branch waveguide Wherein the optical switch is located inside the branch waveguide. 8. The method of claim 7,
Wherein the third interface is located between a first vertex and a second vertex of the main waveguide and the branch waveguide. 5. The method of claim 4,
Wherein the branch angle is greater than or equal to a second reflector angle between the main waveguide and the second interface. 5. The method of claim 4,
Wherein the first interface and the second interface are parallel to each other. 5. The method of claim 4,
Wherein an angle formed between the light incident on the first interface and the first interface is greater than an angle formed between the light incident on the second interface and the second interface. 5. The method of claim 4,
Wherein an angle formed by the light incident on the first interface with the first interface is a right angle. A main waveguide in which light enters and is in a straight line;
A branch waveguide having a branch angle formed at a predetermined angle from the main waveguide and spaced apart from the main waveguide; And
And a reflector whose refractive index is changed by application of a signal,
Wherein the main waveguide and the branch waveguide are connected by the reflector,
And the second refractive index of the reflector is greater than the first refractive index of the main waveguide and the branch waveguide so that light is guided to the branch waveguide. delete 14. The method of claim 13,
A first interface between the main waveguide and the main waveguide of the reflector, the second interface being in contact with the main waveguide of the reflector after being incident into the reflector by refraction from the first interface, Wherein the optical waveguide guides the light to the branch waveguide. 16. The method of claim 15,
And the second reflector angle formed between the main waveguide and the second interface is larger than the branch angle. A main waveguide in which light enters and is in a straight line;
A branch waveguide branching at a predetermined angle from the main waveguide; And
And a reflector whose refractive index is changed by application of a signal,
The second refractive index of the reflector is controlled to be smaller than the first refractive index of the main waveguide and the branch waveguide so as to be refracted from the first interface in contact with the main waveguide of the reflector to the inside of the reflector And the light is guided to the branch waveguide. A main waveguide in which light enters and is in a straight line;
A branch waveguide branching at a predetermined angle from the main waveguide; And
And a reflector whose refractive index is changed by application of a signal,
The first refractive index being a refractive index of the main waveguide and the branch waveguide is controlled to be larger than a first refractive index of the reflector by refraction from the first interface in contact with the main waveguide of the reflector And the light is guided to the branch waveguide. 19. The method of claim 18,
And the angle at which the light incident from the main waveguide is refracted into the reflector at the first interface becomes larger than the angle of incidence at the first interface is used to make the branch waveguide opposite to the inclined direction of the first interface Wherein the optical switch is located at a side of the optical switch.

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