DE3008022A1 - WAVE TYPE CONVERTER FOR ELECTROMAGNETIC WAVES - Google Patents

Description

Letter from Leaf Jr Dlpl.-Ing. G. Schliebs

the German Patent Office, Munch on Patent Attorney

The present invention relates to mode converters for electromagnetic waves, and more particularly to a mode converter which converts the _{TM Q} type to the TE _{Q type.} (The only index is for the orthoradial direction.)

In the electromagnetic wave range, which extends from ultra-short waves to light waves and beyond, the TE _Q propagation type is one of the most interesting. In waveguides with a round cross-section, it shows the lowest attenuation and the best piper properties. In DE-OS 28 05 732 it has been shown that when exciting plasmas of type TE _Q in the presence of an axial constant magnetic field is "inclusive", that is, that when a plasma is generated by placing a strong one on a plague Focused bundle of rays that spreads according to the TE _Q type, part of the plasma remains trapped in the center of the focal point and can reach a temperature there that is much higher than anywhere else.

One can use this property of the confinement of electrons by the type TE _Q to create pseudocathodes in electrolytes and thereby store solar energy by letting them carry out electrochemical reactions

In contrast, type TM ₀ is one of the easiest to generate and filter out. 3k light wave range, it is selected in lasers through conical diopters, the cone angle of which is equal to the Brewster angle. In the ultra-short wave range, the type TM ₀ naturally extends the coaxial basic type.

The mode converter according to the invention has a TM ₀ filter, consisting of a cavity resonator for the TM ₀ type and at least one according to the Brewster

030036/0886

Letter WM sheet Jf WpHne- CL ScMtebs

μ Sas German Patent Office, Munich Patent Attorney

Angle cut diopter in the path of the beam, and is characterized by the fact that it uses materials as plane-parallel plates, which are for those of interest electromagnetic waves are homogeneous but anisotropic. Their thickness and possibly the direction of their anisotropy are so determined that if they pass through a plane and rectilinearly polarized wave, they are the electric Let the field of the wave rotate by ^ - radian.

Sin material is isotropic if its dielectric tensor f, which links the electrical induction D ~ with the electric field Έ according to the equation D "= f · Έ , is a spherical tensor. In the other case it is anisotropic.

A general tensor can always be viewed as the sum of an antisymmetric and a symmetric tenaor. Thereby one can differentiate between two types of anisotropic substances: substances that have a "rotating power" and where f is the sum of a spherical and a symmetrical tensor, and the crystalline substances, where t is a symmetrical tensor but not a spherical one.

Many substances of natural organic origin, such as glucose, have an optical rotation, that is, that the electric field tet, rotates a plane, linearly polarized wave propagation through these substances is proportional to the distance traveled.

According to a first embodiment of the invention, substances with natural turning power are used, which are mostly liquid or in solution to produce a wave type converter. This is what these substances are for in containers closed with plane-parallel plates housed. These panels are see-through and

0 3 0 0 3 6/088)

Letter from the sheet «(Γ Dlpl.-Ing. G. Schllebs

to the German Patent Office, Munich Patent Attorney

are perpendicular to the direction of propagation of the wave and at a distance at which the rotation of the wave polarization equals V; is.

The substances with rotating ability can have an induced rotating ability, i.e. they can have a Faraday effect demonstrate. It is known that the natural turning ability of certain substances can be increased or even can induce a turning ability where originally there was no natural turning ability by using these substances introduces in the containers described in an axial magnetic field. - In this first type of wave type converter the anisotropy is linked to the antisymmetric component of the tensor f.

According to a second embodiment of the invention, use is made of the optical properties of the crystals, specifically the optical half-wave plates. It will be shown that when two half-wave plates are superposed so that the fast and slow axes of one are the bisectors of the angles between the fast and slow axes of the other, they are the plane of polarization of a plane and rectilinearly polarized wave passing through them turn around £ radian. The half-wave plates can be cut in quartz if they are light waves or infrared waves whose wavelengths are of the order of microns. For centimeter waves, anisotropic artificial substances will be described, with which the equivalent of a half-wave plate can be produced _o "

In the following the invention is described in detail with reference to the drawing; in this show:

030036/088 6

Letter from the sheet Ir ^ Dlpi.-Ing. G. Schttebs

to the German Patent Office, Münchsn patent attorney

1 shows a coaxial COg pump laser which _{emits the TM 0} type, with a mode converter which converts this type into the TE type;

2 shows a gas laser in which the filter selective _{for TM Q} and the mode converter _{TM 0 -TE 0} not

have the same relative position as in Fig. 1;

3a shows a device for using the arrangements shown in FIGS. 1 and 3b and 2 in the area of the electrolytes in order to store solar energy

can by making them electro-chemical reactions lets carry out;

Fig. 4a gas lasers in which the type TM _{0 is} filtered out and 4-b and the beam passes through two crossed half-wave plates, which the type

Convert TM ₀ to type TE _0;

Fig. 5 is an explanatory diagram;

Fig. 6 shows an application of the in Fig. 4a and 4b and 7 shown wave converter type in the centimeter wavelength range.

In the example of FIG. 1, 10 _{denotes a C0 2} laser which emits a wave TE. It consists of the COg laser itself, which emits a TM ₀ wave, and a TM * TE _Q wave type converter. The cavity resonator of the laser is delimited by a planar and annular metal mirror 13 and a semi-reflective window 14. In the cavity resonator there are two coaxial cylinder electrodes 101 and 102, between which the ultra-high frequency pulse generator 103 generates pulses. A voltage divider 104 allows the metal mirror 13 to a middle

6/088:

Letter from the sheet fif DIpl.-lng. G. Schliebs

to the German Patent Office, Munich Patent Attorney

The position of the mirror 13 can be adjusted more precisely by means of its holder 105 and micrometers (not shown). The CO ₂ is contained in a container 100 from which it is extracted the cavity resonator is passed approximately below atmospheric pressure.

The COg laser emits a wave TM ₀ . The TM type is filtered by conical diopters 25 and 27 which delimit the transparent block 26 which lies in the cavity resonator. This block is inclined at the Brewster angle of incidence with respect to the axially parallel rays, ie the angle of incidence of this ray is such that its tangent is equal to the optical refractive index of the transparent block. Zinc sulfide and zinc selenide are mostly used as transparent substances for the optics of the waves of 10 μm emitted by COp lasers.

The thickness of the block 26 is chosen to be large enough to focus the rays on the axis. Between the mirror 13 and the diopter 25, the structure of the electric field of the shaft is very similar to the basic coaxial types.

Between the diopter 27 and the window 14 is the propagation type much more similar to type TM in metallic waveguides, at least in its midfield. The decrease of the field at the edge of the beam depends on the exact shape of the mirror. It has been assumed until now that they are flat, but it is advisable to curve the meridians of these mirrors slightly in order to maintain the stability of the To secure steel. The center of curvature must be of one meridian lie on the other, as is known per se. Under these conditions one speaks of an Iiaguerre-Gauss type, doh, that the amplitude of the electric field as a function of the center distance

030036/0886

Letter from the sheet ^ DIpl.-Ing. G. Schliebs

to the German Patent Office, Munich Patent Attorney

a Gauss function multiplied by a Laguerre polynomial, can be represented. In practice, in this case, the radial electric field Ep can be applied to a Point with axis distance ρ by the following Represent function:

E and er are each an electric field and a reference length, which were chosen so that Ep is a maximum and equal to E ₀ when α goes to tr.

The cross-sections of the bundles of rays are large enough to to be able to neglect the axial component of the electric field.

The rays pass through the window 14 into the container 15, which is filled with a fluid with rotating ability. This container is wound with a coil 16.

The turning ability can be natural; in this case the length of the container must be such that the rotation angle of the polarization is equal to "^ radians. In the case of an induced rotation, the strength of the axial magnetic field must be adjusted so that the same value" p of the rotation angle of the polarization is achieved . Thus the direction of the electric field of the TM mode is rotated by "^ -, ie the TK _{Q mode} is converted into the TE _Q type. The rays of this propagation type are then focused by the parabolic mirror 17 on the substance whose core fusion is achieved This substance can be crystallized deuterium, for example, because it is easiest to fuse. The property of the TE mode to enclose a plasma also allows the more difficult fusions of borohydride and lithium hydride or of double hydrides such as

030036/088 5

Letter from sheet ^ DIpl.-lng. G. Schliebs

to the German Patent Office, Munich Patent Attorney

Boranates. ' The fusible hydride is on the magnetic pole 19 laid. The hydride and the magnet form a rotating system that can be rotated about an axis 20 so that the fusible substance that is located at the point of impact of the laser is located, is constantly renewed.

In DE-OS 29 03 175 an X-ray laser is described which has a wave type selector IM ₀ and a container with Faraday effect _{through which the wave QM 0} passes. In this prior publication, the container with the rotating fluid is not used as a wave type converter, but only as a pulse generating system by reducing the overvoltage of the cavity resonator for the wave TM ₀ .

Fig. 2 shows a variant of the laser according to Fig. 1. The cavity resonator of the laser, the mode selector TM _Q and the mode converter TM ₀ - * TE _Q are no longer arranged in this order along the beam, but in the order of the cavity resonator of the laser, Wave type converter TM ₀ - * TE ₀ and wave type selector TM ₀ .

The mode selector includes the Brewster cone 404.

The Faraday Effect Container 415 and the Coil are identical to elements 14 and 15 shown in FIG. 1 have the same functions. The cavity resonator of the gas laser is surrounded by a floodlight lamp and limited by the reflective mirror 405 and the semi-reflective mirror 406.

3a and 3b show the use of the arrangements described so far in the field of electrolytes in order to be able to store solar energy by letting them carry out electrochemical reactions. In Fig. 1, the TE _Q type beam collected the electrons of the generated plasma in its focal point, and the nuclei converged on the negative charges. In Fig. 3a collects

030036/0886

Letter from the BIaH V? IHpL-Jng. 6. Close »

to the German Patent Office, Munich Patent Attorney

The type of wave obtained from solar radiation ΪΕ _{Ο are} the free electrons of the electrolyte (which were released by the photoelectric effect). The negative charges "collected in this way" form the equivalent of a cathode, which attracts the positive ions and then neutralizes them, while other electrons are led to the central zone. This results in electrolysis and thus the possibility of storing solar energy in chemical form.

In Fig. 3a a distinction is made between the same components as in Pig. 1: The wave type filter 126 is like the wave type filter 26 of FIG. 1 by two conical diopters 125 and 127 limited. These diopters are at the Brewster angle of incidence inclined against the planar solar waves that propagate parallel to the axis.

The sunlight is polarized in a statistically isotropic way. The filter 126 only _{transmits the TM 0} mode and reflects approximately half of the energy. The lens 114 closes off the container 115. This container is divided by the wall 121 and contains two rotatable liquids 122 and 123 whose role is to rotate the electric field by 75 · radians. If it were a monochromatic wave, as is the case in lasers, a liquid would suffice. But you need a stable rotation of the electric field in the entire received light wave range. The achromatism is generated using a method known in optics. It is a matter of laying two substances on top of one another, the properties of which change depending on the wavelength in such a way that they balance each other out and produce an achromatic resultant. The coil 116 creates a magnetic field that has the ability to rotate

030036/08 8

Letter from the sheet tC D! Pl.-Ing. G. Schllebs

to the German Patent Office, Mtüichsn patent attorney

of fluids 122 and 123 amplified. The wave type TE _Q generated in this way is focused around the point 118, which is in the vicinity of the pole of the permanent magnet 119. This permanent magnet strengthens the axial magnetic field. The point 118 is located in a cavity 128 in which the liquid that is to be penetrated _{by the TE 0 wave type circulates.} The liquid is supplied to the cavity with line 120 and leaves it through line 120 '. Several cells according to FIG. 3 a are fastened on a metal support 131 with rings 132 and screws 133. This perforated metal support 131 orients a group of cells in the direction of the sun.

4a and 4b show a gas laser which _{emits a wave TM 0} , and behind it a mode converter OM ₀ * TE ₀ .

In FIG. 4 a, the gas-filled cavity resonator of the laser is delimited by the reflecting mirror 201 and the semi-reflecting mirror 202. The flood lamp 203 pumps the active gas. A conical diopter 204 filters the shaft TM _Q. It is raised on the transparent plate, the other side of which carries the mirror 201. _{The TM 0} * TE _Q wave type converter is constructed with two birefringent half wave plates 205 and 206. These plates are oriented so that the fast and slow axes of the first plate are the bisector of the angle formed by the fast and slow axes of the second plate. Such a combination of half-wave plates causes the polarization to be rotated by 75 · radians.

The mode filter of FIG. 4a cannot be used for the high power density because the concentration the energy generated by the rear sight would destroy it.

030036/0886

Letter from the Platt ^ IMpL-lng. G. Schliebs

to the German Patent Office, Müncheo patent attorney

Fig. 5 * explains in detail a Brewster diopter. The direction (i-r) of a ray that is parallel to the axis runs and penetrates the diopter is

tg (i - r) = - ^ (n - -) (See. Formula (1) from DE-OS 29 03 175).

After that the beam at the mirror 201, which is perpendicular to the axis is reflected, it emerges parallel to the axis. Its distance from the ray of incidence is then a. If h is the distance between the tip of the conical diopter and the mirror surface and if one considering that i-tr = U, one can write:

The power that enters the rear sight between rays R and (R + dR) occurs between rays (a - R) and (a - R. - dR) from. You can only use the electric PeId E. write according to the law of the conservation of energy:

2HE ² (R) x RdR = 2llE ² (aR) x (aR) dR (3)

This equation shows that R E (R) must be a symmetric function of R and of (a - R). on the other hand E must increase proportionally to R near the axis.

The simplest function that fits this definition is R ⁵ (a - R) ⁵ . So that will

The wave which passes through the cone 204 twice by being reflected on the mirror 201 has because of the properties of Brewster's angle is type TM. Your axial

Letter from sheet V ^ Dlpl.-Ing. G. Sdiliebs

to the German Patent Office, Munich Patent Attorney

Component is negligible because the radius a des The beam is large compared to the wavelength.

To increase energy accumulation along the axis 4b, the raised conical rear sight 204 according to FIG. 4a was replaced by a recessed conical one Rear sight 204 'replaced. The plane mirror 201 becomes a concave mirror 201 ', which reflects the rays in itself. The other components of Fig. 4b are otherwise with those identical to Figo 4a

The two half-wave plates 205 and 206 are laid out in such a way that the fast and slow axes of one are the bisectors of the fast and slow axes of the other. It is known that when two half-wave plates are cascaded so that the slow and fast axes of one form an angle Jf with the slow and fast axes of the other, the vector of the electric field is two on top of each other the following rotations with respect to two axes which form an angle T experiences. He then turns 2 tf. If T = U,

Tl

the electric field E rotates by £ · As a result, the TM mode changes to the TE _{Q mode} .

The wave type converter according to Figo 4a and 4b is especially suitable for light waves and for infrared waves, since one is used for these waves use birefringent substances.

Since one has no substances that are naturally anisotropic for the centimeter waves, one makes the substance artificially anisotropic, as shown in FIG. 6. In a cylindrical transparent block 250 a plurality of parallel grooves 251 and 252 is incorporated, with lamellae 253 and 254 remain between the grooves. The thickness of the lamellas is aj, the width of the grooves is a ₂ »

030036/088 3

Letter from the sheet '/ £ Dlpl.-Ing. G. Sehlieb "

to the German Patent Office, Munich Patent Attorney

the associated dielectric constants are ß-i and tg. If the sum Ca ₁ + a ₂ ) is much smaller than the wavelength, the stacking reacts to the waves like a homogeneous anisotropic substance whose apparent dielectric constant can be calculated. Pure waves with a polarization that is parallel to the surfaces of the plane-parallel plates can be used to calculate the mean dielectric constant £ //

r - ^a l * ^a 2

V / - a, Va ₂ (5)

ει ε ₂

and for waves with a polarization that is perpendicular to the faces of the plates:

H ⁽⁶⁾

You can find these formulas in the work on layered dielectrics, e.g. "Waves in Layered Media" by Leonid M. Brekhovskikh, Academic Press, 1960, page 83, formula 7.13 and page 84, formula 7.20.

In order to produce a half-wave plate with the stacking of FIG. 6 to be able to, the cuts must have a depth Δ ζ, so that:

izi'SZyy - / T ^) = λ / 2 (7)

^a 1

Appropriately, one chooses the ratio - so that the fact

^ Sin

tor (y ^ // - / F7) becomes a maximum to get the maximum effect to achieve with the smallest room filling and also, thus small tolerances in the ratio grj, which are manufacturing-related not disturb the system. To be able to calculate this optimal ratio, used man the parameter

0 3 J J 3 6/0 8 & ■

Letter from BIaH I ^ Dipl.-lng. G. Schlieb »-

to the German Patent Office, Künchen patent attorney

A ₁ . - a _o Al. - ε.2

^a l ^{+ a} 2 e _x ⁺ e ₂

With this parameter ft, the formulas (5) and (6) write like this:

ει. . + t-2

V / "(ei + ε ₂ ) (1 - ß) ⁽¹⁰⁾

If you set the first derivative g-rr "^ / ^ //" ¹ ^ tT) equal to Full, you get:

1 + β (ει + ε ₂ ) 2

Since ρ »is assumed to be very small, the first part can be used Replace equation (11) with a series expansion in ß> en and then you get:

i \ l

^ε 1 + E

and using equation (8) from / b:

(12)

Λ Ji = IJ-. (13)

^a l ^{+ a} 2 ⁴ C ₁ + C ₂

As an example one can take polystyrene sheets with β ^ 2.56, with gaps from air with £ „= 1 · One obtains then:

= O, lWahsp 4z = O _# 55 and r4e 1 ^a 2 ^a l ^{+ a} 2 ^a l ^a 2

= O _# 55 and r4e: = 0 _r 44 (H) ^aa

030036/0886

Letter from the sheet #T Dlpl.-Ing. G. Schliebe

to the German Patent Office, Munich Patent Attorney

Formula (7) gives the thickness ζ of the half-wave plates, calculated in the direction of the expansion axis

It can be shown that:

= 23 /

e ₂ (ει - ε ₂ )

₁ / - "
is.

The block 250 of Fig. 6 has two parts with lamellae, which form an angle of 45 ° with each other. One can Make it by making parallel and closely spaced saw cuts on either side of a cylindrical Attaches blocks of dielectric. The saw cuts are made so that a full part 255 is in the center of the Block remains.

Some dielectric can be used within the scope of the invention leave the slats to keep the space between the slats. The cut of such a dielectric Block in a plane parallel to xOy is shown in FIG. It shows a series of holes 256 between narrow webs 257. In order to facilitate the shaping of the part, the holes 256 can be slightly conical.

As an example for the use of a mode converter according to Fig. 6, Fig. 8 shows an antenna feeder with a swivel joint. This feeder has a waveguide 301, in which the Y / ellen in type TE _Q spread, a swivel joint 302 with a ball bearing 303, which is driven by a motor 304, and a wave type converter TE ₀₁ - * TM ₀₁ 25Ο according to Fig. 6, which is fixed in the metal housing with 305 polyethylene * screws. With 306 there is a transition

0 3 *. J 3 S / 0 ί L

Letter from the sheet] ^ Dlpl.-Ing. G. Schliebs

to the German Patent Office, Munich Patent Attorney

between the waveguide 307 and the coaxial cable 308 denotes that feeds an antenna (not shown here) ο

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Claims (8)

92260 PONTMAY-AUX-ROSES (France) Wave type converter for electromagnetic waves Patent claims Wave type converter for electromagnetic waves of the Hi ₀ type into those of the TE _Q type with a TM ₀ -PiIter consisting of a cavity resonator for the TM type and at least one diopter cut according to the Brewster's angle in the path of the beam, characterized in that it also Has means which lie in the path of the beam and make the electrical peId of the V / eile TM rotate by ^ radians. 2. Wave type converter according to claim 1, characterized in that that the means consist of a container through which the beam passes and is filled with a liquid with natural rotatory power, the length of the container being in 030036/0886 The fee schedule of the German Chamber of Patent Attorneys applies to the contractual relationship · Place of jurisdiction for performance and payment: Darmstadt Telephone calls are not legally binding I Letter from sheet f Dlpl.-Ing. Q. Loves to the German Patent Office, Munich. Patent attorney Beam direction is chosen so that the angle of rotation of the electric field of the type TM _{0 is} equal to ⁷ ^ radians. 3. wave type converter according to claim 1, characterized in that the means consist of a container (400) which is penetrated by the beam and is filled with a liquid with Faraday effect, and means (416) which are in the liquid generate a variable electric field in the direction of the beam, the intensity of which is selected so that the angle of rotation of the electric field of the TM type is equal to % radian. 4. wave type converter according to claim 1, characterized in that that the funds from two halves enplated for the frequency of the wave TM, which is transmitted by the / Bundles of rays are penetrated and are so placed, that the slow and fast axes of the first half-wave plate are the bisectors of the angles between the slow and fast axes of the second plate are. 5. wave type converter according to claim 1, characterized in that the means consists of an elongated block (250) exist, which has lamellae (253, 254) of a first transparent material at each end, which of lamellae (251, 252) of a second transparent material are separated, and in the middle a full part has, the planes of the lamellas of one end with the planes of the lamellas of the other end one Form a 45 ° angle. 6. mode converter according to one of claims 1 to 5, characterized in that the cavity resonator is that of a gas laser. 030036/0883 ORIGINAL INSPECTED Letter from the sheet ϊΓ WpHng. Q. Schllebs to the German Patent Office, Munich Patent Attorney 7. Wave type converter according to claim 2 or 3 for a broadband wave of the TM _Q type, characterized in that the container (115) has at least two compartments (122, 123), each of which is filled with a fluid that has a natural or induced rotational ability that changes differently with frequency. 8. mode converter according to claim 6, characterized in that one end of the cavity resonator (200) of a plane mirror (201) is bounded by a projecting cone (204) of transparent fabric carries whose cone angle is equal to the complement of Brewster's angle, so that the cone axis parallel rays on the mirror at the Br ewster angle get an idea. 9 · Wave type converter according to claim 6, characterized in that that one end of the cavity resonator (200) is limited by a conical mirror (201 ·), the one has recessed cone (204 ') made of transparent fabric, the cone angle of which is equal to the complement Brewster's angle is so that the cone axis parallel rays incident on the mirror at the Breweter angle and reflected by this in itself will. 30036 / 03Λ