KR100317655B1 - Channel waveguides and their applications - Google Patents

Abstract

The present invention relates to integrated optical channel waveguides and their applications as switches, modulators and sensors.

The channel waveguide has the shape of a channel-like structure located within or over the planar substrate material and narrowed geometrically narrowly, and the confinement is positioned perpendicular to the propagation direction of the light.

A single mode integrated optical broadband channel waveguide has been described which can deliver light from the entire visible wavelength range, for example a single mode, which is effective, i.e. with low light attenuation, . If necessary, the light can be converted or modulated in a wavelength-dependent or wavelength-independent manner, for example, by means of electro-optical means.

The channel waveguide is basically manufactured by means of known processes, for example refractive index change.

Description

Channel waveguides and their applications

The present invention relates to an integrated-optical channel waveguide. New features of channel waveguides open applications requiring modulation and / or switching and / or spatial integrated light components of different wavelengths and / or at least one wavelength range. The present invention relates to a patent application entitled " Splice Splitter Consisting of Channel Waveguide and Its Application " and " Color Image Generation System and Its Application "

Prior Art

One of the main methods established in integrated optics for representing integrated-optical channel waveguides and devices based on them is to select the shape and material parameters of the channel waveguide suitable for the limited wavelength given to the application purpose in a suitable manner. Due to the known facts prevalent in optical communication technologies, especially the transmission characteristics of standardized single mode and multimode optical fibers, currently available substrate materials, waveguide fabrication techniques and structural transfer processes (e.g. photolithography) The attention of integrated optics has so far focused almost exclusively on wavelength applications in the infrared spectrum. In contrast to this background, it has hitherto not been necessary in the integrated optics to study the optical bandwidth within the meaning of the definitions given herein, ie the wavelength range in which light is efficiently induced along the channel waveguide simultaneously in a single mode. In the entire paper of integrated optics, there is no study of channel waveguides on these topics, nor a description of the effective refractive index of the modes induced as a function of wavelength. Therefore, theoretical calculations on this subject have not been published, or channel waveguides have not been proposed, manufactured or studied, and the optical bandwidth defined above includes, for example, a wavelength range of 400 nm, particularly the entire visible wavelength spectrum.

For transmission, modulation and / or switching of light by an integrated optical device, it is necessary to fabricate an optical fiber waveguide, for example a channel waveguide or an optical fiber, which is based on an increase in refractive index in the waveguide region (in W. karthe, R. Intergrier Optics (Integrated Optics), Akademische Verlagsgesellschaft Geest & Porting K.-G., Leipzig, 1991).

Other choices for optical transmission or optical modulation are provided by quasi-waveguides such as ARROW (in: M. Mann, U. Trutschel, C .; L. Leine, F. Lederer "Directional coupler-based on antiresonant reflecting optical waveguide: Opt. Lett., Vol. 16 (1991), No. 11, pp 805-807).

For effective modulation and / or switching of light, the waveguide preferably derives only the fundamental mode. Thus, different light wavelengths require different values for the waveguide characteristic parameters, which generally require the use of different waveguides for different light wavelengths in general.

Single mode fibers, on the other hand, have known properties that efficiently transmit light in a single mode and within a wide spectral range.

However, until now, no channel waveguide on or within the substrate material has been known, which is characterized by the induction of light of different wavelengths, and the wavelengths are substantially 130 < RTI ID = 0.0 > Nm (value applied only to visible light).

Problems of the Invention

The present invention is based on the problem of inducing light of several wavelengths or wavelength ranges in a single mode in one same channel waveguide. And the light waves transmitted to the channel waveguide allow switching or modulation if desired. For a wavelength range of approximately 130 nm (a value that applies only to visible light), the emission of different wavelengths permits a sufficiently efficient transmission from a technical point of view. In addition, sensors with new features are developed.

Significance of invention

The object of the present invention is achieved for a channel waveguide having the feature according to the main claim. Claims 27 to 28 are advantageous to another embodiment based on the main claim.

The present invention is in the successful manufacture of a channel having the following features: a single mode and a narrowly defined narrow channel in the direction perpendicular to the propagation direction of light. Such a channel is also characterized by the property of transmitting light using a relatively wide bandwidth (claim 26).

Narrowly defined in two dimensions means that a channel can be fabricated, which represents a waveguide structure as a waveguide strip used on grooves or substrate recessed in a substrate, the structure being characterized by a narrowly defined cross-sectional shape. This cross-sectional shape may take any form, in particular in the form of strips, or in the form of rectangles, triangles, circles, ellipses or polygons.

The grooves or strips applied may be realized by specific modifications of the appropriate substrate material or by a combination of at least two materials. The processes necessary for this relationship are basically known. If dispersion d (n ₂ -n _s ) / dλ required for induction is greater than or equal to 0, broadband light transmission is advantageous (claim 28).

Further, if the dispersion of the refractive index increase required for induction, d (n ₂ -n _s ) / dλ, is greater than or equal to 0, then the waveguide having a channel not narrowly defined has the characteristic of transmitting light in a relatively wide bandwidth Was also found (claim 27).

In each case a single mode integrated optical broadband channel waveguide, hereinafter referred to as SOWCW, which allows wide bandwidth and single mode optical transmission. The wide bandwidth can be transmitted with a technically sufficient efficiency in a single mode with different wavelengths, in particular in the visible spectrum with a bandwidth of [Delta] [lambda]> 0.48 x [lambda] - 85 nm (where the units of lambda and DELTA lambda are nm) . For visible light, this means a bandwidth greater than about 100 nm (Figure 7b).

The single mode means that one effective refractive index can be assigned for each given wavelength in the wavelength range (FIG. 7a).

Here, light means visible light and invisible light, which are infrared and ultraviolet electromagnetic radiation. Transmission with a technically sufficient efficiency means that the effective refractive index N _eff of the mode induced to SOWCW is at least 5 x 10 ^-10, which is greater than the refractive index n _s of the surrounding material, where n _s is the substrate refractive index n ₁ ) or the value of the plate refractive index (n ₃ ). This is a necessary prerequisite to achieve low value waveguide attenuation in the 1dB / cm range and to meet the channel waveguide for efficient use in technical applications.

For each given wavelength in the range between [lambda] ₁ and [lambda] ₁ + [Delta] [lambda], one effective refractive index can be assigned which is the effective refractive index of the fundamental mode ( _N00 ). Single-mode range is by the effective vibration increase in the fundamental mode (N ₀₀₎ at a wavelength (λ ₁ + △ λ) from a technical point of view the one hand and on the other hand the first of the lateral direction at a wavelength (λ ₁₎ from a technical point of view, Is determined by the effective vibration increase of the mode (N ₀₁ ) or the depth-wise primary mode (N ₁₀ ). The values of [lambda] ₁ and [lambda] ₁ + [Delta] [lambda] are determined by the medium surrounding the shape / material fl ow meter and channel waveguide of the channel waveguide. In principle, the minimum value (? _Min ) of the wavelength that can be used and the maximum value (? _Max ) of the wavelength that can be used are determined by the transmission range of the material used.

For the crystal material KTiOPO ₄ , for example, the minimum value is almost 350 nm and the maximum value is approximately 4 μm.

Also, since light is commonly coupled in a SOWCW by a single mode optical fiber, technically efficient means that the optical coupling efficiency between the waveguide attenuation and the SOWCW and the single mode optical fiber in the wavelength range that can be induced in the entire single mode is more than 30% It means that you do not. Using standard channel waveguides, it is not possible, for example, to derive red and blue light in a single mode and in one and the same channel waveguide with technically sufficient efficiency. The refractive index of the parameter substrate, the refractive index of the SOWCW, the refractive index of the SOWCW or the one-dimensional or two-dimensional refractive index distribution, the sectional shape (for example, the width and the depth) and the position of the SOWCW in or on the substrate are Δλ> 130 nm ), That is, for a given wavelength within this range, one effective refractive index can be individually allocated (in: W. Karthe, R < RTI ID = 0.0 > . Integrated Optics, Akademische Verlagsgesellschaft Geest & Portig K.-G., Leipzing, 1991).

In particular, optical waves of the entire visible wavelength spectrum can be derived. The optical wave induction at one and the same SOWCW over the entire visible spectrum is single mode and has the same efficiency from a technical point of view. Thus, this is a practical single mode white light channel waveguide.

The SOWCW according to the present invention is characterized by a process specially adapted for its manufacture and its special properties. The physical requirements associated with the substrate material are the production of narrowly defined structures in the lateral direction (i.e., by using diffusion anisotropy during ion exchange), and / or the refractive index increase required for wave induction associated with the material surrounding the SOWCW by Is the variance of:

Wherein if the _{n 1> n 3, n s} = n 1; When n ₃ > n ₁ , n _s = n ₃ .

SOWCW is manufactured by one of the following processes:

- ion exchange and ion diffusion in dielectric crystals such as KTiOPO ₄ (KTP), LiNbO ₃ and LiTiO ₃

- ion exchange in glass,

- injection molding, stamping or centrifuging processes with polymers on suitable substrates such as Si, which produce ribs or inverted ribs or Peterman waveguides,

- SOWCW in II-VI or III-V semiconductor materials produced by epitaxial deposition on suitable substrate materials such as SiO ₂ for use in infrared wavelength spectrum,

- SOWCW in II-VI or III-V semiconductor materials produced by doping or alloying for use in the infrared wavelength spectrum,

SOWCW in heterostructures of triple or quaternary II-VI or III-V semiconductor materials,

- ribs or inverted ribs in II-VI or III-V semiconductor materials or Peterman waveguides,

- a suitable substrate material by combining Si, SiO ₂ , SiON layers, and / or other oxide and / or nitride layers, preferably in Si or on top of SOWCW,

- Sol-Gel process on suitable substrate materials (S. Pelli, GC Righini, A. Verciani: "Laser Writing of optical waveguides in sol-gel films", SPIE 2213, International Symposium on Integrated Optics, pp. 58-63, 1995),

- ion implantation in all of the above materials.

Ion exchange and ion diffusion in dielectric crystals, or ion exchange processes in glass, are advantageously coupled to the ion implantation process to obtain a narrowly defined structure.

The SOWCW according to the present invention allows optical wave guidance, optical modulation, and / or optical switching in a wide spectral range.

Phase, amplitude modulation and / or polarization of light are performed in SOWCW according to one of the following principles.

- electro-optic, acousto-optical, thermo-optic, magnetic-optical, opto-optical or photo-

A change in the effective refractive index due to injection or depletion of a free charge carrier in the semiconductor material,

Opto-electric, opto-electro-optic, opto-optic, or opto-thermo-optic, acousto-optic, thermo-optic,

Modulation that changes the effective refractive index by injection or depletion of a free charge carrier in a semiconductor material, using the Fabry-Perot effect;

Opto-electric, opto-optic, acousto-optic, thermo-optic,

Blocking modulation to change the effective refractive index by injection or depletion of a free charge carrier in a semiconductor material,

- Controllable waveguide amplification,

- Controllable polarization conversion,

- waveguide mode conversion, or

- Electron-absorption modulation.

The light modulation can also be performed outside the SOWCW by the following means.

A change in the coupling efficiency between the light source and the channel waveguide, or

Modulation of the light source itself, or

A light attenuation device (e.g., a wedge filter), or

A phase shifter (for example, a fork cell) or

A polarization converter as an external device,

The light modulation in the SOWCW can also be performed in phase, amplitude and polarization directions.

The external electric field (E _elektr. ) Influences the refractive index of the substrate material as well as the effective refractive index of the mode to be induced, with a reasonable approximation, according to the following formula.

Where the refractive index of the material is n _ij , the linear electron-optical tensor is r _ijk, and i, j is 1, 2, 3.

By activating an appropriate tensor component, the refractive index of the material itself and / or the double refraction of the material can be changed. For a given linear optical polarization, n _ij is reduced to the active effective refractive index.

The phase modulation is changed by changing the propagation constant, i.e., the effective refractive index N _eff , with respect to the wavelength in accordance with the following equation in the phase of the induced mode.

Where L is the length of the electric field affecting the SOWCW, which is typically the active electrode length. In addition, the following equation applies to the channel waveguide.

Amplitude modulation or luminance modulation in SOWCW refers to modulation using blocking modulation or an integrated-optic Fabry-Perot resonator. Since the blocking modulation implies that the refractive index increase (n ₂ -n _s ) required for wave induction is reduced, the attenuation of the waveguide mode increases strongly and, in extreme cases, it is no longer possible to propagate to the waveguide mode. Thus, the brightness of the light at the light output of the SOWCW can be set to a value between 0 and the maximum value.

The polarization modulation means that the double refraction change caused by the above-mentioned effect is changed in the polarization state of the light to be induced.

In all the forms of modulation referred to here, the channel waveguide has the property that the null induces wavelengths from the spectral range into a single mode.

If the above principles are used, the light in the entire spectrum of the visible light can be derived and modulated in a single mode by one SOWCW.

Simultaneous induction of electromagnetic radiation into a single mode within several wavelengths or wavelength ranges within the range of Δλ> 0.48 × - 85 nm is also possible in other spectral ranges, eg ultraviolet or infrared wavelength spectrum, if the SOWCW exhibits an appropriate size Loses. The above-mentioned range is limited by the transmission range of the material used.

The SOWCW characteristic enables applications that provide a basis for a new group of microsystem-technology devices, for example, by using interference processes, for example, for measurement techniques, sensor science, photometric measurement and spectral spectroscopy.

The SOWCW according to the present invention provides the following advantages.

- single-mode broadband transmission of light;

Within the technical sense, effective optical modulation and / or switching capacity in the GHz range (depending on current state of the art);

Depending on the requirements, it is possible to select a wavelength-dependent modulation device or a wavelength-independent modulation device (for example, electro-absorption modulation, light source modulation, wedge filters)

- a low electro-optic modulation voltage (several volts), thus a good combination of processes, structures and devices in microelectronics, compared to a fork or Kerr cell;

When using KTP as the substrate material, high optical performance density can be induced in SOWCW without interfering with any phase change (high resistance of material to photoinduced change of refractive index)

Aggregation for the entire visible light spectrum - Optical broadband channel waveguides represent a fundamental innovation in integrated optics, for example in the field of multi-media, sensor science, measurement technology and spectral spectroscopy, which in principle allows the classification of entirely new solutions.

Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 shows a diagram of the structure and progress of the refractive index in a Ti: LiNbO ₃ channel waveguide,

FIG. 2 shows a single mode range of a Ti: LiNbO ₃ channel waveguide,

FIG. 3 shows a diagram of the structure and the progress of the refractive index in Rb: KTP-SOWCW,

FIG. 4 shows a single mode range of Rb: KTP-SOWCW,

5 shows the arrangement of the SOWCW in the substrate material or on the top and the cross-sectional shape of the waveguide region,

6 shows Rb: KTP-SOWCW with a phase modulator,

7 shows a general view of a technically related wavelength range for single mode wave induction in the SOWCW,

Figure 8 shows the sensor application of the SOWCW.

Implementation of the invention

The characteristics of the known titanium-diffusion channel waveguide in LiNbO ₃ are shown in FIG. 1 and FIG. 2.

In the present invention, this is in contrast to the characteristics of the single mode integrated-optical broadband channel waveguide (SOWCW), which is characterized in that the bandwidth of the waveguide using rubidium ← → potassium ion exchange channel waveguide in KTP is shown in FIGS. Is shown in FIG. 4, as well as in the second figure, the selected figure is the effective refractive index N _eff which is related to the refractive index value n ₁ of the substrate as a function of the wavelength λ. Each waveguide mode can be assigned a larger effective refractive index N _eff between n ₂ and n ₁ or n ₃ . The value of _Neff depends on the wavelength, substrate and waveguide refractive index, or substrate and waveguide refractive index distribution, and waveguide shape. Thus, each mode having an exponential ik (i, k > = 0, integer) is diagrammed by the effective refractive index N _ik as a line, where 1 represents the order of the depthwise mode, Order.

For a given wavelength from the wavelength range, if the effective refractive index can be assigned, the waveguide is in a single mode. From a technical point of view, for sufficient light induction, the effective refractive index of the associated mode is at least 5 x 10 ^{-5, which} is greater than n ₁ and / or n ₃ . Thus, the bandwidth can be read directly. Figure 7a is a general view of a single mode wavelength range that can be efficiently derived (from a technical point of view) in a channel waveguide.

7b according to the direct dependency of the wavelength itself in turn LiNbO ₃ standard titanium-diffused channel waveguide, as well as it shows a single mode wavelength range derivable for SOWCW according to the invention in KTP. Also in FIG. 7b, the region of the SOWCW according to the present invention can be generally scoped from the channel waveguide of the state of the art.

Figures 1 and 2 provide an initial drawing using an embodiment of a titanium-diffusion channel waveguide.

Figure 1 shows a channel waveguide (2) in a substrate material (1).

To produce a standard channel waveguide, titanium-diffusion is performed in X-section lithium niobate (LiNbO ₃ ) in this embodiment (RV Schmidt, I, P. kaminow, Appl. Phys. Lett., Vol. ), No. 8, pp. 458-460). For this purpose, the titanium strip 11 is sputtered on the substrate surface. At temperatures above 950 ° C, titanium diffuses into the crystal. In the lateral direction, the diffusion constant is almost twice the depth direction, which is why the strip is considerably wider. Following the diffusion time period (t _d ), the refractive index distribution for the initial strip width (w) obtains the shape described by the formula below.

Titanium-diffused channel waveguides can not induce light with a bandwidth of several hundred nanometers in the visible light wavelength spectrum in a single mode (see Fig. 7b). The waveguide 2 is provided with a groove having a width (a) and a depth (t) which are mostly not geometrically defined.

The flaw has a refractive index distribution with a surface refractive index (n ₂ = n _w (x '''= 0, y''' = 0), which increases the refractive index n ₁ of the surrounding substrate material. The diagram of FIG. 1 shows the qualitative progress of the refractive index in the x and y directions. Safe transition of refractive index progression is common in the x direction (direction x "is shown here substantially) and in the y direction (direction y" is shown here substantially).

The second figure shows the single mode range of the titanium-diffused channel waveguide in the X-section LiNbO ₃ selected as the embodiment (X = crystallographic X-axis corresponds to the y-axis of FIG. 1). The graph shows the effective refractive index for the Z-polarization of the fundamental mode N ₀₀ and the lateral mode first mode N ₀₁ (N _eff , _z , Z = the crystallographic Z axis corresponds to the x axis of FIG. 1 ). A sputtering titanium strip of w = 3.0 μm wide and 15 nm thick is used as a diffusion source. The diffusion temperature is 1000 占 폚, and the diffusion time is 3 hours.

The ratio of the titanium-ion diffusion constant in LiNbO ₃ is D _x / D _y 2.

The depth distribution is calculated as follows.

The lateral refractive index distribution is calculated as follows.

Here, a _x = 2 (D _x t _d ) ^{l / 2} , which corresponds to width a / 2 in FIG. Also, a _y = 2 (D _y t _d ) ^{l / 2} , corresponding to depth t in Fig. When? = 500 nm, n ₁ = 2,2492, n ₂ - n ₁ = 0.0080, the dispersion of the substrate refractive index (n ₁ ) is smaller than zero. The value t _d represents the diffusion time and erf represents the error function (cf J. Ctyroky, M. Hofman, J. Janta, J. Schrofel, " 3-D Analysis of LiNbO ₃ : Ti channel Waveguides and Directional Couplers, J. of Quantum Electron., Vol. QE-20 (1984), No. 4, pp. 400-409). The channel waveguide described here has a technically effective meaning, which leads only to the fundamental mode in the range of 490 nm to 620 nm, that is, the bandwidth becomes [Delta] [lambda] = 130 nm. The effective refractive index is calculated using the effective index method (GB Hocker, Wk Burns, "Mode dispersion in diffused channel waveguides by the effective index method", Appl. Optics, Vol. 16 (1977) 118).

In the present invention, Figure 3 shows, in this embodiment, a single mode integrated optical broad band channel waveguide (SOWCW) 2 in a substrate material 1 made of Z-section KTiOPO ₄ (KTP). , J.-P. Ruske, K. Hornig, A. Rasch, "Fabrication and Characterization of Singlemode Channel Waveguides and Modulators in KTiOPO ₄ for the Short Visible Wavelength Region", SPIE 2213, International Symposium on Integrated Optics (1994) pp. 152-163).

The substrate material 1 is provided as a mask opening the gap only at the following waveguide positions. Rubidium-potassium ion exchange is effective in melting nitric acid rubies with barium nitrate and potassium nitrate components. The diffusion has a remarkable effect only in the depth direction with the refractive index distribution formation described below. And becomes a stepwise distribution of the refractive index in the lateral direction. The fabrication of a narrow structure with an abruptly defined range ensures that transmission from the mask to the waveguide occurs at a ratio of 1: 1 due to the lack of lateral diffusion.

The dispersion in Rb: KTP is d (n ₂ -n ₁ ) / d? This dispersion is suitable for the single mode characteristics of the waveguide within a relatively wide wavelength range ([Delta] [lambda]). This SOWCW (2) is a single mode over a wavelength range of approximately 400 nm. The SOWCW (2) is provided with a groove of a very limited shape with a width (a) and a depth (t). The grooves have a refractive index distribution with a surface refractive index (n ₂ = n _w (-a x '' 0, y '' = 0)), which increases the refractive index n ₁ of the surrounding substrate material.

The diagram of FIG. 3 shows the qualitative progress of the refractive index in the x and y directions. a relatively large increase in refractive index from n ₁ to n ₂ in the y direction (the y 'direction is substantially shown here) is common in the x direction (the x "direction is shown substantially here) .

FIG. 4 shows the characteristics of a rubidium-potassium ion exchange SOWCW selected in KTiOPO ₄ according to the present invention.

The graph shows the effective refractive index (N _eff , _z , Z = the crystallographic Z-axis corresponds to the y-axis of the third _figure ) for the Z-polarization of the fundamental mode N ₀₀ and the first mode N ₀₁ in the lateral direction Respectively. At? = 500 nm, n ₁ = 1.9010; The variance of the substrate refractive index (n ₁ ) is less than zero (described in: LPShi, Application of crystals of the KTiOPO ₄ -type in the field of integrated optics, Dissertation Univ, Cologne (1992)).

The effective refractive index is calculated using the effective index method.

Also, n ₂ -n ₁ = 0.0037 = (constant) is applied to the entire wavelength range.

With respect to the diffusion constant, the following holds. D _x / D _y ? 10 ^-3 .

The lateral refractive index distribution is a stepped distribution with width a = 4.0 [micro] m (see FIG. 3). The depth distribution is calculated as follows.

_{n w = n 1 + (n} 2 - n 1) * erfc (-y "/ t) where, t = 4.0㎛, = erfc is complementary erotic SOWCW function described in this embodiment are - technical means available And within the range of 470 nm to 870 nm-only the fundamental mode, i.e. the bandwidth is [Delta] [lambda] = 400 nm.

The manufacture of the SOWCW described in this embodiment is basically known. Waveguides are prepared by ion-exchanging rubidium with potassium in a Z-section potassium titanyl phosphate substrate material (KTiOPO ₄ , KTP) (JD Bierlein, A. Ferretti, LH Brixner, WY Hsu, " Fabrication and characterization of optical waveguides in KTiOPO _{4 &} quot ;, Appl. Phys. Lett., Vol. 50 (1987), No. 8, pp. 1216-1218).

The Z-section means that the crystal level at which the waveguide is produced lies perpendicular to the crystallographic Z-axis.

Here, the fact that diffusion during ion exchange occurs only in the depth direction is used (JD Bierlein, H. Vanherzeele, " Potassium titanyl phosphate: properties and new applications ", J Opt. Soc. (1989), No. 4, pp. 622-633).

FIG. 5 shows a possible cross-sectional shape of the SOWCW in or on the substrate material.

5a shows a waveguide 2 inserted into the substrate material 1 as a rectangular, trapezoidal or triangular groove,

5b shows the waveguide 2 inserted into the substrate material 1,

5c shows a waveguide 2 disposed on the substrate material 1 as a rectangular, trapezoidal or triangular channel,

Figure 5d shows that a rectangular, trapezoidal or triangular strip 5 is formed on a waveguide with a stripe-shaped overlay ensuring lateral guidance of light (ridge guide)

5e shows a rib waveguide, and

5f shows the inverted rib waveguide.

In all embodiments of FIG. 5, the optical parameters are set such that SOWCW is produced as shown in Figures 3 and 4 in the case of Rb: KTP.

FIG. 6 shows the application of the SOWCW according to the invention with an electrode structure 4 for phase modulating the light derived from the SOWCW 2. The possibility of optical modulation is realized using a substrate material that allows for selection to change the phase of the input optical signal. The input optical signal is a light of wavelength lambda or several individual wavelengths lambda _i and / or light of one or several wavelength ranges DELTA lambda _i .

By using large linear electro-optic coefficients, KTiOPO ₄ offers the possibility of using electro-optic phase modulation. On the KTP substrate 1, the SOWCW 2 and the electrode 4 are arranged to form an electro-optic modulator. The light from the light source 3 is connected to the light input E of the SOWCW 2. The voltage V applied to the electrode 4 controls the phase that can be used at the light output A for other uses do. SOWCW has the property of deriving light from a broad spectral range in a single mode (Δλ> 130 nm applies only to visible light).

SOWCW of FIG. 6 is prepared with ion exchange (rubidium for potassium) in a Z-section potassium titanyl phosphate substrate material (KTiOPO ₄ , KTP). To use the largest coefficient r ₃₃₃ of the linear electro-optical tensor (r _ijk ), the electrode arrangement according to FIG. 6 is required on the substrate surface, where the first electrode is flatly applied next to the waveguide bumps , And the second electrode covers the SOWCW (2).

Due to the voltage U applied to the electrodes, the component of the electric field E _z is generated in the Z direction in the illustrated region (Z = the crystallographic Z axis corresponds to the y direction in FIG. 3).

In the following equation,

This has a phase shift effect that can be described as:

Where r ₃₃₃ is a linear electro-optic coefficient for Z-polarization, an electric field is applied in the Z direction, Γ is an overlap factor between the electric field and the induced optical mode in the channel waveguide, d is the electrode length, Length.

In addition, the following equations apply to channel waveguides.

For a given control voltage (U), the phase shift _i are different from the different wavelengths [lambda] _i .

In the first embodiment, the light of the individual wavelength? ₁ is connected to the optical input E of the SOWCW 2. This light is phase modulated. The effect corresponds to a known channel waveguide.

In the second embodiment, at least two separate wavelengths? ₁ and? _{2 are} connected to the SOWCW (2) input (E). Depending on the applied modulation voltage, the phase shift ₁ ) has a phase shift? ₂ ). However, the SOWCW (2) does not lose the property of guiding light into a single mode. In contrast to the background of the present state of the art, such modulation is possible up to frequencies in the GHz range and includes frequencies in the GHz range. The control voltage U for complete modulation is between 0 and almost 4 volts for electrode lengths in the mm range and electrode distances in the micrometer range.

Figure 7a shows a general view of the wavelength range technically relevant for a single mode wave induction in the SOWCW according to claim 26; By "technically relevant" is meant that the effective refractive index (N _eff ) is at least 5 × 10 ^-5 , greater than n _s , where n _s is the substrate index of refraction (to ensure a sufficiently small waveguide attenuation, eg 1 dB / n ₁ ) or the plate refractive index (n ₃ ). For each given wavelength in the range between λ ₁ and λ ₁ + Δλ, one effective refractive index, ie the fundamental mode N ₀₀ ) can be assigned. The single mode range on the one hand, from the technical point of view, by effective oscillation enhancement of the fundamental mode (N ₀₀ ) at the wavelength (λ ₁ + Δλ) (λ ₁₎ the lateral direction a first mode (N ₀₁₎ or the depth direction the first mode is determined by the effective vibration increase of the (N _10). λ ₁ to the value of λ ₁ + △ λ is the material parameters of the shape and the waveguide in And the medium surrounding the waveguide. In general, the minimum value (λ _min) and a maximum (λ _max) which can be used with a wavelength that can be used is determined by the transmission range of the material used. Thus, for example, λ _min is little with respect to a crystallized material KTP 350m and λ _max is nearly 4㎛.

The 7b turns Ti: as a function of wavelength (λ) the wavelength range (△ λ) that can be transmitted in a single mode of: (KTP Rb) channel waveguide and SOWCW according to the invention according to the current state of the art consisting of LiNbO ₃ Respectively.

Calculation of the effective refractive index on which the determination of the wavelength range DELTA lambda that can be transmitted in the single mode is performed is performed according to an effective index method similar to that of FIGS. 2 and 4, wherein the reference wavelength (? ₁ = 500 nm) Is calculated.

Based on the known wavelength dependence (dispersion) of the refractive index increase (n ₂ -n ₁ ) required for light induction as well as the wavelength dependence (dispersion) of the substrate index of refraction n ₁ and from the specific reference wavelength λ ₁ Initially, the first waveguide depth t, then waveguide width a (until each of the vibration amplitudes for the first mode), and finally the wavelength lambda (when the fundamental mode N ₀₀ disappears) Is changed in this calculation.

The upper limit of the wavelength range that can be transmitted in the single mode is the wavelength (? ₁ + ??), where the effective refractive index of the channel waveguide is 5 x 10 ^-5 larger than the substrate refractive index (n ₁ ). The size of the wavelength range that can be transmitted in a single mode is dependent on each reference wavelength (λ ₁ ). (Rb: KTP) in KTP, corresponding to the standard titanium-diffusion channel waveguide (Ti: LiNbO ₃ ) in lithium niobate from the state of the art, , The size of the wavelength range DELTA lambda that can be transmitted in the single mode satisfies the inequality DELTA lambda > 0.48 x lambda-85 nm. (Where [lambda] and [Delta] [lambda] are described as nm)

The area corresponding to SOWCW is indicated in gray in FIG. 7B. If necessary, the wavelength range that can be induced into the single mode is limited by the light transmission range limit of the substrate material, for example, when λ ₁ <λ _min or λ ₁ + Δλ> λ _max (see also FIG. do.

Using an appropriate substrate or waveguide material, the inequality may also be applied to wavelengths greater or less than those shown in Figures 7a and 7b.

FIG. 8 shows an embodiment for using the SOWCW (2) in a sensor application. 8a, the absorption effect of the measurement medium (gas, liquid, solid) on the equatorial field of the wave guided to the SOWCW (2) (placed on the plate) is measured and evaluated. For this purpose, the surface of the substrate material 1 in contact with the medium is covered with a buffer layer 7 (e.g. SiO ₂ ), except for the interaction window region 6. In this way, the imaginary field can only be accessed in the interactive window region 6. In the area of only a predetermined length, the interaction window 6 does not constrain SOWCW (2). At the optical input (E) of the SOWCW (2), light is coupled. At the light output A of the SOWCW 2, the light affected by the measuring medium can be used for evaluation, for example, the light intensity measurement can be achieved by the detector 8. SOWCW (2) is characterized by deriving a light component of a different wavelength (? _I ) from a broad wavelength spectrum.

In contrast to known channel waveguides, the measured wavelengths can be adapted to the material being irradiated as well as the material being irradiated over a relatively wide spectrum of wavelengths. Measurements can be made immediately on the measurement medium at various wavelengths ([lambda] _i ).

It is advantageous that the light components in SOWCW are modulated by an amplitude modulator (not shown) corresponding to SOWCW.

A change in the waveguide attenuation occurs due to the absorption of the measurement medium itself or by a change in the surface dispersion. Here, the fact that an electric field or a part of the magnetic field distribution is induced outside of the channel waveguide itself (the imaginary field) is used by using the induced wave. Thus, such electric or magnetic field components can be accessed outside the channel waveguide. If the absorption medium is on the channel waveguide, i. E. In the plate, the absorption-dependent equatorial field is attenuated or the surface dispersion of the channel waveguide is changed by using the medium in the interaction window 6, Not necessary. Both change the waveguide attenuation and this can be measured by the photometer test facility.

Also, the propagation constant of the induced mode is changed due to the influence of the measurement medium. This can be measured by an interferometer test fixture, for example using a Mickelson interferometer according to FIG. 8b.

The substrate 1 having the SOWCW 2 is disposed in the optical path between the beam splitter 10 and the reflector 9.

Another embodiment is that the interaction window 6 is coated with a material which is responsive to physical, chemical or biological external influences and which influences the response of the light and / or the waveguide itself when the material is reacted to external influences .

8C, the reflectance of the channel waveguide section B of the SOWCW 2 is determined by the amount of measurement in the sensor. The following variants are provided.

a) The measuring medium acts as the reflector 9 itself and is in contact with or at a constant distance from the cross-section (B) of the waveguide, or

b) the reflector 9 uses a reaction material as a reflective coating, or the reaction material itself is a reflector 9, wherein the reaction material changes the reflectance according to the ambient measurement medium, or

c) The reflector 9 is disposed at a certain distance from the cross section B of the waveguide, and the measurement medium is disposed between the waveguide section B and the reflector 9.

If the distance is short, for example in the range of only a few micrometers, no additional beam forming device is needed.

Using such a facility, the light of at least one wavelength? _{I is} connected from the - wideest possible wavelength spectrum to the optical input E of the SOWCW (2). For the optical output A, the light component of the reflected light or fluorescence, which is influenced by the measuring medium, corresponding to the optical input E, is measured by the beam splitter 10. The integrated optical performance of the measuring equipment according to FIG. 8 is suitable for the application of the reduced structure and micro system technology.

Since the minimum sample amount is used and the measurement is performed with a significant measurement sensitivity, and the interaction window 6 is larger than SOWCW (2), the length of the interaction window is within the millimeter range.

By means of the measuring equipment, all physical, biological and chemical quantities of gases, liquids and solids which influence the action of the induced light or the action of the SOWCW (2) itself can be measured.

And for a given measurement facility, including SOWCW, the wavelength and wavelength range can be freely selected from the broad wavelength spectrum.

Claims (13)

A surface-type substrate material (1) The channel-like structure is fabricated in or on the surface-type substrate material 1 by a process of changing the refractive index of the substrate material or by applying an appropriate material, The refractive index n ₁ of the substrate, the refractive index n _s of the substrate, the refractive index n _w = f (xy) in the waveguide region of the channel structure, the cross-sectional shape (width a and depth t and the position of the channel waveguide 2 in or on the substrate material are set according to the dependency of the wavelength? transmitted in at least one ultraviolet, visible or infrared region, The waveguide 2 is characterized in that single mode light induction is performed in a wavelength range DELTA lambda given that DELTA lambda is greater than or equal to 0.48 x -85 nm and one effective refractive index is assigned to each wavelength in the wavelength region Channel waveguide. The method according to claim 1, Wherein the channel structure is narrowly defined in two dimensions perpendicular to the propagation direction of light (Z axis). The method according to claim 1, Wherein the wavelength dependency in the channel-type structure is d (n ₂ -n _s ) / dλ greater than or equal to zero. The method according to claim 1, Wherein the channel waveguide is composed of rubidium ← → potassium ion exchange potassium titanyl phosphate (KTiOPO ₄ , KTP), and the wavelength range (Δλ) includes a wavelength range greater than 350 nm in the visible light wavelength spectrum. The method according to claim 1, Wherein the cross-section of the channel-type structure is one of the following types: a rectangular, an oval, a circular, a triangle, or a polygon. The method according to claim 1, The channel- Embedded in the substrate material 1 as a channel, or Inserted into the surface of the substrate material 1, or Is applied to the surface of the substrate material (1). The method according to claim 1, Characterized in that the substrate material (1) comprises glass or dielectric crystals and the process for varying the refractive index comprises an ion exchange process or an ion diffusion process. 8. The method of claim 7, Wherein the dielectric crystal includes diffusion anisotropy and the diffusion constant in the depth direction is larger than the diffusion constant in the lateral direction. The method according to claim 1, Wherein a substrate material (KTP) having a high linear electro-optic coefficient is used for electro-optic modulation of light. The method according to claim 1, Characterized in that the channel-like structure is applied by injection molding, stamping or centrifuging using at least one polymer on the substrate material (1). The method according to claim 1, The substrate material 1 is a II-IV or III-V11 semiconductor material, The process of changing the refractive index An epitaxial deposition process, or Doping process, or Alloy process, or Injection of a heterostructure of semiconductor material, or And forming a rib waveguide or an inverted rib waveguide. 8. The method of claim 1 or 7, Wherein the step of varying the refractive index is a sol-gel process. The method according to claim 1, Wherein the step of changing the refractive index is an ion implantation step.