WO2003003502A1

WO2003003502A1 - Ring resonator method for separating orthogonal resonance modes and method for adjusting a ring resonator

Info

Publication number: WO2003003502A1
Application number: PCT/EP2002/006011
Authority: WO
Inventors: Martin Josef Schallner
Original assignee: Marconi Communications Gmbh
Priority date: 2001-06-29
Filing date: 2002-05-31
Publication date: 2003-01-09
Also published as: EP1271686A1

Abstract

The invention relates to a ring resonator (10) for use in microwave systems wherein orthogonal resonance modes are formed and geometrical characteristics influence at least one of the resonance modes. Said geometric characteristics include at least one recess (12, 14, 16, 18, 20, 22, 24, 26) which partially interrupts the ring resonator (10) in a radial direction, whereupon the frequency of at least one of the orthogonal resonance modes is influenced. The invention also relates to a method for separating orthogonal resonance modes in a ring resonator (10). The invention further relates to a method for adjusting a ring resonator (10).

Description

Ring resonator, method for separating orthogonal resonance modes and method for balancing a ring resonator

The invention relates to a ring resonator for use in microwave systems in which orthogonal resonance modes are formed and in which geometric features influence at least one of the orthogonal resonance modes. The invention further relates to a method for separating orthogonal resonance modes in a ring resonator, in which at least one of the orthogonal resonance modes is influenced by geometric features. The invention further relates to a method for adjusting a ring resonator.

State of the art

Planar ring resonators are used in numerous applications, for example as notch filters, bandpass filters and oscillators. Compared to other known resonators, they can be produced in a particularly simple manner, for example using thin-film techniques on aluminum oxide ceramics. Furthermore, they generally have a high quality Q in comparison to other planar resonators. Due to the symmetrical structure of the ring resonator and the different coupling mechanisms of the microwaves, there are always two orthogonal resonance modes. These generally differ slightly in their frequency. For some applications, for example for filters, both resonance modes are used specifically. In other applications, however, it is necessary to suppress a mode. This applies in particular to oscillator applications, where the oscillator resonance frequency must be clearly defined.

It has already been proposed to influence the ring resonators by means of geometric features with regard to their resonance modes, namely by introducing a gap into the ring resonator. This is described, for example, in Lu, Shih-Lin and Ferendeci, A.M. : "Varactor tuned ring resonator microwave oscillator", Electronics Letters, Vol. 32, No. 1, 1996, pages 46-48. However, a disadvantage of this solution is that it leads to an increase in radiation losses, as a result of which the quality of the resonator decreases. Another disadvantage of this solution is that in addition to harmonic resonance modes (for example 2 λ, 3 λ, 4 λ, ...) resonance modes at fractions (for example 1.5 λ, 2.5 λ, 3.5 λ) , ... ) may occur.

Advantages of the invention

The invention builds on the generic ring resonator in that the geometric features include at least one recess, which the resonator in radial Direction partially interrupts, so that the frequency is influenced by at least one of the orthogonal resonance modes. To provide a clear resonance frequency in a ring resonator, it is therefore not necessary, for example for oscillator applications, to completely suppress the undesired resonance mode. Rather, it is sufficient to separate the two orthogonal modes with respect to their resonance frequencies by a certain amount. In this way, unambiguous operation at the desired resonance frequency can be provided based on only one resonance mode.

The ring resonator according to the invention is developed in a particularly advantageous manner in that the arrangement of the at least one recess as a function of the position of at least one coupling line is selected such that the position of the at least one recess lies in the range of a current maximum of the resonance mode to be influenced , The recesses, which can also be referred to as notches, lie at the geometric positions or in the vicinity of the geometric positions at which the current maximum of one of the resonance modes occurs. In this way, the resonance frequency of this mode is shifted to lower frequencies. Due to the orthogonality of the two resonance modes in the ring resonator, there is minimal influence on the other mode. A satisfactory separation of the resonance frequencies can thus be achieved. In a particularly advantageous embodiment of the ring resonator according to the invention it is provided that two diametrically opposite recesses are provided. If the ring resonator is a resonant of length λ, the current maxima of a mode are completely detected by two diametrically opposite recesses. In the case of a 2λ ring, two of four possible positions are recorded in the case of two diametrically opposite recesses, in the case of a 3λ ring, two out of six possible positions and so on.

It can also be provided that four recesses are provided, which are diametrically opposed in pairs. In the case of a ring with a length of 2λ, all positions can thus be occupied with maximum current through recesses. It is also conceivable that more than four recesses are provided, in particular in the case of ring resonators, which have a length which is a multiple of the wavelength.

It is particularly useful that the at least one recess is arranged on the inner radius of the ring resonator. Since the current through the ring structure is generally concentrated on the inner radius of the ring resonator, a recess on the inner radius of the ring edge is particularly efficient. Therefore a frequency shift of a mode that can be achieved with a recess on the inner radius is greater than with. a recess of the same size on the outer radius of the ring resonator.

Nevertheless, it can also be useful that the at least one recess on the outer radius of the ring resonator nators is arranged. In this way, the frequency shift of the positioning of the recess can be specifically influenced by ^'.

For the same reason, it can be useful to develop the ring resonator according to the invention in such a way that the at least one recess is arranged between the inner radius and the outer radius of the ring resonator. In addition to the different positioning of the recesses, it is also possible to influence the effect of the recesses by shaping. For example, the recesses can have essentially rectangular boundaries. However, it is also conceivable that the boundary describes a rounded shape without corners.

The invention is based on the generic method for separating orthogonal resonance modes in a ring resonator in that the geometric features include at least one recess which partially interrupts the resonator in the radial direction, so that the frequency is influenced by at least one of the orthogonal resonance modes. To provide a unique resonance frequency in a ring resonator, it is therefore not necessary, for example for oscillator applications, to completely suppress the unwanted resonance mode. Rather, it is sufficient to separate the two orthogonal modes with respect to their resonance frequencies by a certain amount. In this way, clear operation can be provided at the desired resonance frequency based on only one resonance mode. The method according to the invention is developed in a particularly advantageous manner in that the arrangement of the at least one recess as a function of the position of at least one coupling line is selected such that the position of the at least one recess lies in the range of a current maximum of the resonance mode to be influenced. The recesses, which can also be referred to as notches, are located at the geometric positions or in the vicinity of the geometric positions at which the current maximum of one of the resonance modes occurs. In this way, the resonance frequency of this mode is shifted to lower frequencies. Due to the orthogonality of the two resonance modes in the ring resonator, there is minimal influence on the other mode. A satisfactory separation of the resonance frequencies can thus be achieved.

In a particularly advantageous embodiment of the method according to the invention it is provided that the two recesses are arranged diametrically opposite one another. If the ring resonator is a resonator of length λ, the current maxima of a mode are completely detected by two diametrically opposite recesses. In the case of a 2λ ring, two of four possible positions are recorded in the case of two diametrically opposite recesses, in the case of a 3λ ring, two out of six possible positions and so on.

The method can also be carried out in such a way that four recesses are diametrically opposed in pairs. be arranged accordingly. In the case of a ring with a length of 2λ, all positions can thus be occupied with maximum current through recesses. It is also conceivable that more than four recesses are provided, in particular in the case of ring resonators, which have a length which is a multiple of the wavelength.

It is particularly useful that, in the context of the method according to the invention, the at least one recess is arranged on the inner radius of the ring resonator. Since the current through the ring structure is generally concentrated on the inner radius of the ring resonator, a recess on the inner radius of the ring edge is particularly efficient. Therefore, a frequency shift of a mode can be achieved with a recess on the inner radius, which is larger than with a recess of the same size on the outer radius of the ring resonator.

Nevertheless, it can also be useful in the context of the method according to the invention that the at least one recess is arranged on the outer radius of the ring resonator. In this way, the limit displacement can be influenced in a targeted manner by positioning the recess.

For the same reason, it can be useful to develop the method according to the invention in such a way that the at least one recess is arranged between the inner radius and the outer ^" radius of the ring resonator. In addition to the different positioning of the recesses, it is also possible to use the To influence the effect of the recesses by shaping. For example, the recesses can have essentially rectangular boundaries. However, it is also conceivable that the boundary describes a rounded shape without corners.

The invention further relates to a method for producing a coordinated ring resonator, in which at least one recess is made in the ring resonator by a laser, said recess partially interrupting the ring resonator in the radial direction. The use of a laser during the adjustment process of the ring resonator to make the recesses enables particularly precise structures to be achieved, as a result of which a ring resonator with precise adjustment can also be provided.

In particular, it is useful that the adjustment method according to the invention is carried out while the ring resonator is in operation. It can thus be observed during the insertion of the recess in which way the resonance frequency of the mode in question shifts, so that ultimately a desired frequency splitting can be made available.

The invention is based on the knowledge that it is not necessary for the reliable functioning of ring resonators, in which a clear resonance frequency is required, to completely suppress the undesired mode. It is therefore not necessary to introduce a gap in the ring resonator and thus to accept the disadvantages mentioned in connection with radiation losses. Rather, a frequency splitting of the two orthogonal modes by the provision of recesses or notches according to the invention in the ring resonator.

drawings

The invention will now be explained by way of example with reference to the accompanying drawings using preferred embodiments.

It shows:

1 shows a ring resonator with an adjacent coupling line;

Figure 2 shows a first arrangement of coupling line and ring resonator with two recesses;

3 shows a second arrangement of coupling line and ring resonator with two recesses;

Figure 4 shows a first arrangement of coupling line and ring resonator with four recesses;

Figure 5 shows a second arrangement of coupling line and ring resonator with four recesses;

FIG 6 ^'sonator onierten a Ringre having different positive and shaped recesses; Figure 7 shows an arrangement of ring resonator and two coupling lines; and

Figure 8 shows another arrangement of ring resonator and two coupling lines.

Description of the embodiments

FIG. 1 shows a ring resonator 10 with an adjacent coupling line 28. In the arrangement shown consisting of ring resonator 10 and coupling line 28, there is an essentially inductive coupling. Such an inductively coupled arrangement is used as an example in the following explanations of preferred embodiments of ring resonators according to the invention.

FIG. 2 shows a first arrangement of coupling line 28 and ring resonator 10 with two recesses 12. A resonance mode in the ring resonator 10 can be shifted with respect to its frequency through the recesses 12. If the ring resonator 10 has a length of λ, the recesses 12 for one of the modes (mode A) have the two possible positions which correspond to the current maxima. In the case of a resonance ring 10 of length 2λ, the two recesses 12 assume two of four possible positions for mode A. For a resonance ring 10 of length 3λ, the recesses 12 occupy two of six possible positions. The same applies accordingly to rings of a length of further multiples of the wavelength λ. FIG. 3 shows a second arrangement of coupling line 28 and ring resonator 10 with two recesses 14. Here, ring resonator 10 with recesses 14 is arranged with respect to coupling line 28 in such a way that a frequency shift of the mode B orthogonal to mode A from FIG. 2 takes place. For a ring resonator 10 of length λ, the recesses 14 are in two of two possible positions for shifting the resonance frequency of mode B. For a ring resonator 10 of length 2 λ, the recesses 14 are in two of four possible positions for shifting the Resonance frequency of mode B. With a ring of length 3λ two of six possible positions for the recesses 14 are shown when the resonance frequency of mode B is shifted. The same applies correspondingly to larger multiples of the wavelength λ.

FIG. 4 shows a first arrangement of coupling line 28 and ring resonator 10 with four recesses 16. Here, the relative arrangement of ring resonator 10 and coupling line 28 is selected such that the four recesses 16 are located in positions in the ring resonator 10, so that for fashion A in the case of a ring resonator 10 of length 2λ there is a frequency shift, o in the case of the stated length of the ring resonator 10 all four possible positions for the recesses 16 are exhausted. In the case of ring resonators 10 with a greater length, not all possible positions are covered by the positions of the recesses 16 shown.

FIG. 5 shows a second arrangement of coupling line 28 and ring resonator 10 with four recesses 18. Here the relative arrangement of the ring resonator 10 and the coupling line 28 is selected such that the four recesses 18 are located at positions in the ring resonator 10, so that for mode B a frequency shift takes place in the case of a ring resonator 10 of length 2λ, with said length of the ring resonator 10 all four possible positions for the recesses 18 are exhausted. In the case of ring resonators 10 with a greater length, not all possible positions are covered by the positions of the recesses 18 shown.

FIG. 6 shows a ring resonator 10 with differently positioned and shaped recesses 20, 22, 24 and 26. The recess 20 is arranged on the inner radius 30 of the ring resonator 10. Such an arrangement leads to a large frequency shift, since the current is concentrated on the inner radius 30 of the ring resonator 10. However, for the purpose of a smaller frequency shift, it is also possible to provide a recess 22 which is arranged on the outer radius 32 of the ring resonator 10. It is also possible to arrange a recess 24 between the inner radius 30 of the ring resonator 10 and the outer radius 32 of the ring resonator 10. Furthermore, a recess 26 is shown on the outer radius 32 of the ring resonator 10, which differs in shape from the recesses 20, 22 and 24. In contrast to the recesses 20, 22, 24, which have a substantially rectangular shape, the recess 26 has a rounded shape. A recess with a rounded shape such as the recess 26 does not have to lie on the outer radius 32 of the ring resonator 10. Rather, it can also on the inner radius 30 and between the inner radius 30 and the outer radius 32 of the ring resonator 10 may be arranged.

FIG. 7 shows an arrangement of ring resonator 10 and two coupling lines 34. Here, an embodiment is shown in which there is an essentially capacitive coupling between ring resonator 10 and coupling lines 34. The features of the present invention explained in connection with FIGS. 2 to 6 can equally be used for the coupling structure shown in FIG.

FIG. 8 shows a further arrangement of ring resonator 10 and two coupling lines 36. The principles of the present invention explained above also apply to such an arrangement with two coupling lines 36, which couple essentially inductively with ring resonator 10.

The preceding description of the exemplary embodiments according to the present invention is only for illustrative purposes and not for the purpose of restricting the invention. Various changes and modifications are possible within the scope of the invention without leaving the scope of the invention and its equivalents.

Claims

Expectations

1. ring resonator (10) for use in microwave systems,

- in which orthogonal resonance modes are formed and

where geometric features influence at least one of the orthogonal resonance modes,

characterized in that the geometric features comprise at least one recess (12, 14, 16, 18, 20, 22, 24, 26) which partially interrupts the ring resonator (10) in the radial direction, so that the frequency of at least one of the orthogonal ones Resonance modes is influenced.

2. Ring resonator (10) according to claim 1, characterized in that the arrangement of the at least one recess (12, 14, 16, 18, 20, 22, 24, 26) is chosen as a function of the position of at least one coupling line (28) is that the position of the at least one recess (12, 14, 16, 18, 20, 22, 24, 26) is in the range of a current maximum of the resonance modes to be influenced.

3. Ring resonator (10) according to claim 1 or 2, characterized in that two diametrically opposite recesses (12, 14) are provided.

4. ring resonator (10) according to any one of the preceding claims, characterized in that four recesses (16, 18) are provided which are diametrically opposed in pairs.

5. Ring resonator (10) according to one of the preceding claims, characterized in that the at least one recess (12, 14, 16, 18, 20) is arranged on the inner radius (30) of the ring resonator (10).

6. ring resonator (10) according to any one of the preceding claims, characterized in that the at least one recess (22, 26) on the outer radius (32) of the ring resonator (10) is arranged.

7. ring resonator (10) according to any one of the preceding claims, characterized in that the at least one recess (24) between the inner radius (30) and the outer radius (32) of the ring resonator (10) is arranged.

8th . Method for separating orthogonal resonance modes in a ring resonator (10)

in which at least one of the orthogonal resonance modes is influenced by geometric features, characterized in that the geometric features comprise at least one recess (12, 14, 16, 18, 20, 22, 24, 26) which partially interrupts the ring resonator (10) in the radial direction, so that the frequency of at least one of the orthogonal ones Resonance modes is affected.

9. The method according to claim 8, characterized in that the arrangement of the at least one recess (12, 14, 16, 18, 20, 22, 24, 26) is selected as a function of the position of at least one coupling line (28) so that the position of the at least one recess (12, 14, 16, 18, 20, 22, 24, 26) is in the range of a current maximum of the resonance modes to be influenced.

10. The method according to claim 8 or 9, characterized in that the two recesses (12, 14) are arranged diametrically opposite.

11. The method according to any one of claims 8 to 10, characterized in that four recesses (16, 18) are arranged diametrically opposite in pairs.

12. The method according to any one of claims 8 to 11, characterized in that the at least one recess (12,

14, 16, 18, 20) is arranged on the inner radius (30) of the ring resonator (10).

13. The method according to any one of claims 8 to 12, characterized in that the at least one recess (22,

26) is arranged on the outer radius (32) of the ring resonator (10).

14. The method according to any one of claims 8 to 13, characterized in that the at least one recess (24) between the inner radius (30) and the outer radius (32) of the ring resonator (10) is arranged.

15. A method for adjusting a ring resonator (10), in particular according to one of claims 1 to 7, characterized in that at least one recess (12, 14, 16, 18, 20, 22, 24, 26) of a laser in the ring resonator (10) is introduced, which partially interrupts the ring resonator (10) in the radial direction.

16. The method according to claim 15, characterized in that the adjustment method according to the invention during the

Operation of the ring resonator (10) is performed.