JPH06214275A - Waveguide type optical nonlinear element - Google Patents

Abstract

PURPOSE:To provide the waveguide type optical nonlinear element which has a high function and excellent light transparency and a novel multilayered structure by combining a high-polymer material exhibiting an electrooptical effect and a high-polymer material having excellent transparency in order to realize a multilayered electrooptical material. CONSTITUTION:This waveguide type optical nonlinear element has at least two pieces of core parts 1, 2, a clad part 3 having the refractive index lower than the refractive index of these core parts and upper and lower electrodes disposed in the form of holding the core parts. At least two pieces of the core parts are disposed to hold the clad part therebetween in a direction perpendicular to a substrate 6. The one core part is constituted of the nonlinear high- polymer material exhibiting a primary electrooptical effect and the other core part 1 is constituted of the high-polymer material which does not exhibit the electrooptical effect. This nonlinear element is combined with a switching element existing in a direction horizontal with the substrate in order for light to be switched between the waveguides disposed in a direction perpendicular to the substrate, by which the light is three-dimensionally guided and the high- function element having a high degree of integration is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical non-linear element, and more particularly, to a small-sized optical element which makes use of the features of both an optical non-linear material exhibiting an electro-optical effect and a polymer material having excellent transparency. In addition, the present invention relates to a highly functional optical waveguide device having a high degree of integration.

[0002]

2. Description of the Related Art A typical element utilizing the electro-optic effect is an optical modulator using lithium niobate. This element has a structure in which titanium is diffused on the surface of a lithium niobate substrate, this portion serves as a core, and a metal electrode is formed above the core. On the other hand, in the fields of advanced optical communication and optical information processing in the future, compact and highly functional optical waveguide devices are expected. Among them, in order to increase the degree of integration, a method of stacking a number of high-performance optical waveguides not only on the substrate plane but also in the direction perpendicular to the substrate can be considered. However, when lithium niobate is used as the material exhibiting the electro-optical effect, it is difficult to stack the lithium niobate crystal substrate as it is, and therefore, lithium niobate is crystal-grown on any substrate. It was also extremely difficult to achieve multi-layering.

On the other hand, when a polymer material exhibiting an electro-optical effect is used, the possibility of stacking is higher than that of lithium niobate, but there are many materials having poor light transmittance, and it is high if an optical waveguide is composed of this material alone. Highly functional integration is difficult.

In order to solve the above problems, the present invention realizes multi-layering of an electro-optical element, which has been difficult with inorganic materials such as lithium niobate. It is intended to provide an optical functional device having a new multilayer structure which is highly functional and excellent in light transparency by combining excellent polymer materials.

[0005]

In order to solve the above-mentioned problems, a waveguide type non-linear element according to the present invention comprises at least two core parts, and a clad part having a refractive index lower than those of the core parts. A waveguide-type optical nonlinear element having upper and lower electrodes arranged so as to sandwich the core portion, wherein at least two core portions are arranged sandwiching the cladding portion in a direction perpendicular to the substrate. The core part is made of a non-linear polymer material exhibiting a first-order electro-optical effect, and the other core part is made of a polymer material not showing an electro-optical effect.

Further, the second waveguide type optical nonlinear element of the present invention comprises at least two core parts, a clad part having a refractive index lower than those of the core parts, and above or below the clad. In a waveguide type optical non-linear element having an electrode and at least two core portions sandwiching a cladding portion in a direction perpendicular to a substrate, one of the core portions exhibits a first-order electro-optical effect. It is characterized in that it is made of a non-linear polymer material, and the other core part is made of a polymer material that does not exhibit an electro-optical effect.

In the present invention, a polymer material exhibiting an electro-optical effect capable of easily forming a thin film by a spin coating method is used as the first core layer, and a polymer material having excellent light transmittance is used as the second core layer. The most important feature is that the optical waveguides are formed in multiple layers in the direction perpendicular to the substrate and that the electrodes required for the electro-optical element can be easily formed at any position where the electro-optical effect can be efficiently exhibited. Further, the functional operation of the switch or the like is performed mainly by guiding the light to the first core layer, and the other portions are mainly guided to the second core layer having a high light-transmitting property, so that the entire device is processed. It is also characterized by reducing the optical waveguide loss. In an element using a single crystal of an inorganic material such as lithium niobate, it is necessary to diffuse an inorganic material such as titanium from the surface to form the core part of the waveguide, and it is difficult to form a multilayer. It is almost impossible to form electrodes at arbitrary positions.

The basic structure and function of the present invention are shown in FIGS.
Will be explained. Reference numeral 1 is a core portion made of a polymer having excellent electro-optical effect and not showing an electro-optical effect, 2 is a core portion made of a polymer showing an electro-optical effect, 3 is a clad portion,
The core portion is a portion where light is guided as a channel waveguide. The core portions 1 and 2 are optically weakly coupled to each other with the clad portion interposed therebetween, and form a coupling portion of the directional coupler. Reference numeral 4 is an upper electrode, 5 is a lower electrode, and 6 is a substrate of the device.

Since one core portion 2 of the core portions 1 and 2 is made of a polymer having a primary electro-optical effect, when a voltage is applied between the upper and lower electrodes 4 and 5, the core portion 2 is refracted. The rate changes. Therefore, when light is incident from the incident end, the core portion 2 is irradiated from the emission end according to the magnitude of the applied voltage.
Since the refractive index of the light changes and light is emitted from either the upper core 1 or the lower core 2, the light switching operation can be performed by controlling the voltage. Such a switch operation can be performed between the upper and lower cores 1 and 2 by combining with a waveguide that operates in the same plane to form a multistage switch not only on one plane but also in a three-dimensional configuration. Is dramatically improved.

The present invention will be described below with reference to examples.

[0011]

[Embodiment 1] FIG. 1 is a sectional view of a main portion of this embodiment. Reference numeral 1 is a core portion having excellent light transmittance, 2 is a core portion showing an electro-optical effect, 3 is a cladding portion, 4 is an upper electrode,
Reference numeral 5 is a lower electrode, and 6 is a substrate of the device. Here, a silicon substrate with thermally oxidized silicon is used.

The manufacturing method will be described below.

Chromium (50 Å) was sprinkled on the thermally-oxidized silicon by the sputtering method and the gold was continuously spun on without breaking the vacuum.
I attached 00Å. A resist pattern matching the shape of the electrode was formed thereon by a normal photo process, and the lower layer electrode 5 shown by 5 was formed by ion milling in argon gas. An epoxy-based UV-curable resin was laminated thereon by a spin coating method to a thickness of 15 μm and irradiated with UV rays for 10 minutes. Next, an acrylic polymer (azo acrylic resin) having an azo dye bonded thereto was laminated to a thickness of 5 μm by spin coating. A resist pattern having a width of 5 μm is formed on this by a normal photo process, and reactive reactive ion etching (RI) in oxygen gas is performed.
After performing step E), the resist was removed to form the lower waveguide core portion 2 of FIGS.

Next, an epixy type ultraviolet curing resin is added to a thickness of 8 μm.
When spin-coated to a thickness of 1 and irradiated with ultraviolet rays, the uppermost surface of the epoxy resin became flat. As a result, the distance between the upper surface of the core and the uppermost surface of the epoxy resin was 3 μm. Then, on top of that, add 0.5 from the refractive index of the cladding.
The epixy-based UV-curing resin having a high% refractive index is laminated by spin coating, and is irradiated with UV rays, and the core part 1 is manufactured by the same method as the method for manufacturing the lower core part 2 described above. It was spin-coated and irradiated with ultraviolet rays. Further, the upper electrode 4 was manufactured by the same method as the above lower electrode manufacturing method.

The overall thickness of the waveguide portion is 43 μm, and 5 × is formed by sandwiching a 3 μm thick ultraviolet curable resin therein.
Channel waveguide 2 made of 5 μm azo acrylic resin
Thus, the channel waveguide 1 made of 5 × 5 μm UV curable resin was formed. This element is heated to 140 ℃ and heated to 1800
A voltage of V was applied between the upper and lower electrodes, the temperature was lowered to room temperature, and then the voltage was lowered. By this poling treatment, the channel waveguide 2 of the azo type acrylic resin comes to exhibit the electro-optical effect.

In order to measure the characteristics of the resulting device, light having a wavelength of 1.3 μm was introduced from the waveguide 2 by batting a fiber, and the emitting end was observed with an infrared camera while applying voltage to the electrodes. When the voltage was 0V, the upper waveguide was bright and the lower waveguide 2 was dark, but when a voltage of 15V was applied, it was confirmed that the upper waveguide 1 was dark and the lower waveguide 2 was bright. It was confirmed that light switching occurs between the individual channel waveguides.

[0017]

[Embodiment 2] FIG. 2 is a sectional view of a main portion of this embodiment. Reference numeral 7 is a core portion exhibiting an electro-optical effect, 8 is a core portion excellent in light transmittance, 9 is a cladding portion, and 1 is a core portion.
Reference numeral 0 is a substrate of the element, and 11 is an electrode.

The manufacturing method will be described below.

On the silicon substrate 10 with thermally oxidized silicon, an epoxy ultraviolet curing resin was laminated by a spin coating method to a thickness of 15 μm, and ultraviolet rays were irradiated for 10 minutes.
Next, an epoxy-based UV curable resin having a refractive index of 0.5% higher than that of the UV curable resin was spin-coated to 5 μm
Was laminated to the thickness of and was irradiated with ultraviolet rays. A resist pattern having a width of 5 μm is formed on this by a normal photo process, reactive reactive ion etching (RIE) in oxygen gas is performed, and then the resist is removed to form the lower core portion 8. .

Next, an epoxy-based UV curable resin is added to 8 μm.
When spin-coated to a thickness of 1 and irradiated with ultraviolet rays, the uppermost surface of the epoxy resin became flat. As a result, the distance between the upper surface of the core and the uppermost surface of the cladding epoxy resin is
It became 3 μm. Then, an azo dye-based acrylic resin is laminated thereon by spin coating, an upper core portion 7 is manufactured by a method similar to the above-described method for manufacturing the core portion, and an epoxy ultraviolet curing resin is spun to a thickness of 20 μm. It was coated and exposed to UV light.

Further, 50 Å of chromium was applied by the sputtering method, and 1000 Å of gold was continuously applied without breaking the vacuum. A resist pattern matching the shape of the electrode was formed thereon by a normal photo process, and the upper electrode 11 was formed by ion milling in argon gas.

The total thickness of the waveguide portion is 43 μm, and 5 × 3 × 3 μm thick ultraviolet curable resin is sandwiched in the waveguide portion.
Channel waveguide 7 made of 5 μm azo acrylic resin
A channel waveguide 8 made of 5 × 5 μm UV curable resin was formed.

This device was heated to 140 ° C., a voltage of 1800 V was applied between the electrode 11 and the silicon substrate 10, and the temperature was lowered to room temperature as it was, and then the voltage was lowered. By this poling treatment, the channel waveguide 7 made of azo-based acrylic resin comes to exhibit the electro-optical effect. Where the electrodes are
It constitutes a coplanar type high frequency electrode, and when an alternating electric field is applied, the electric field is distributed in the polymer containing the core, and the refractive index of the core can be controlled.

In order to measure the characteristics of the resulting device, light having a wavelength of 1.3 μm was introduced from the two waveguides by batting the fiber, and while applying an AC voltage of 100 kHz to the electrodes, both output ends were respectively connected to the fiber. connection,
Furthermore, an infrared detector was connected, the signal from the infrared detector was connected to a synchroscope, and changes in the waveform were observed. When the applied voltage is 0 V, a waveform corresponding to the upper waveguide being bright and the lower waveguide being dark is observed, and when the applied voltage is 18 V, a waveform corresponding to the upper waveguide being dark and the lower portion being bright is observed. It was It was confirmed that light switching occurs between the two channel waveguides by controlling the voltage of the electrodes.

[0025]

As described above, according to the present invention, in order to allow light to be switched between the waveguides arranged in the vertical direction with respect to the substrate, the invention is combined with the switching element in the horizontal direction with respect to the substrate. Light can be guided three-dimensionally, and a highly integrated device with high integration can be realized. The loss of the azo dye-based polymer shown in the example is 1.3.
1.5 dB / cm at the wavelength of μm, on the other hand, the loss of the UV curable resin having excellent light transmittance is 0.3 at the wavelength of 1.3 μm.
It is dB / cm. Therefore, from the viewpoint of light loss, it is more advantageous to optically guide the core portion using the ultraviolet curable resin as much as possible in the case of configuring the element, except for providing the switch function. In this way, by configuring the device by sharing the role of the polymer that exhibits the electro-optical effect for the part that has the switch function and the polymer with excellent light transmission for the waveguide part that connects this part, the integration degree can be improved. It is possible to realize a highly functional element having high light transmission property.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a waveguide type optical nonlinear element having a structure in which electrodes of the present invention sandwich a waveguide.

FIG. 2 is a perspective view of the waveguide type optical nonlinear element.

FIG. 3 is a cross-sectional view of a waveguide type optical nonlinear device having a structure in which an electrode of the present invention is on a waveguide.

FIG. 4 is a perspective view of the waveguide type optical nonlinear element.

[Explanation of symbols]

 1 Core part made of polymer showing no electro-optical effect 2 Core part made of polymer showing electro-optical effect 3 Cladding part 4 Upper electrode 5 Lower electrode 6 Substrate of element 7 Use polymer showing electro-optical effect The core part 8 The core part using the polymer which does not show the electro-optic effect 9 The clad part 10 The substrate of the element 11 The electrode

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Michiyuki Amano 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Toshio Watanabe 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo No. Japan Telegraph and Telephone Corp. (72) Inventor Haruki Ozawaguchi 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corp.

Claims (2)

[Claims] 1. At least two core parts, a clad part having a refractive index lower than those of the core parts, and an upper electrode and a lower electrode arranged so as to sandwich the core parts, and at least two of the core parts are provided. The core portion is a waveguide type optical non-linear element arranged with a cladding portion sandwiched in a direction perpendicular to the substrate, wherein one of the core portions is made of a non-linear polymer material exhibiting a first-order electro-optical effect, and the other of the core portions is formed. A waveguide type optical non-linear element, characterized in that the core portion is made of a polymer material that does not exhibit an electro-optical effect. 2. At least two core parts, a clad part having a refractive index lower than those of the core parts, and an electrode arranged above or below the clad, wherein at least two core parts are provided. In a waveguide type optical non-linear element arranged with a clad part sandwiched in a direction perpendicular to a substrate, one of the core parts is composed of a non-linear polymer material exhibiting a first-order electro-optical effect, and the other core part is A waveguide type optical non-linear element characterized by being composed of a polymer material which does not exhibit an electro-optic effect.