Optoelectronic Oscillator

Abstract

An optoelectronic oscillator (1) comprising at least one electrical-optical conversion unit (LD1) and one optoelectronic conversion unit (PD1), wherein light that can be emitted by the electrical-optical conversion unit (LD1) during operation can be modulated, and during operation, a portion of the light from the electrical-optical conversion unit (LD1) is irradiated onto the optoelectronic conversion unit (PD1), and a modulated electrical signal generated in the optoelectronic conversion unit (PD1) by the irradiated light of the electrical-optical conversion unit (LD1) is used to control the modulation of the light that can be emitted from the electrical-optical conversion unit (LD1) during operation, thereby forming an oscillation during operation.

Description

[Technical Field]

[0001] The present invention relates to an optoelectronic oscillator. [Background technology]

[0002] With the advancement of digitalization, there is an increasing demand for systems with optical clock and signal distribution, which require a specific average signal power with a specific optical modulation at various spatial locations.

[0003] In most cases, a laser followed by an electro-optical modulator and possibly an optical splitter is used for this purpose.

[0004] While it is possible to build such a system using discrete components, it would be very expensive and energy inefficient due to the need to bias the modulator at a specific operating point, and would also require an external electrical signal generator to control the modulator.

[0005] For example, in the paper "J. Lightwave Technol., Vol. 5, p. 380, DOI: 10.1109 / JLT.1987.1075509" by Stephens, WE and Joseph, TR, a system for generating an optical signal by modulating the current of a laser diode is shown as a known technique, in which the modulation signal itself is generated by an external source, and finally an electrical control signal is added to the DC current of the laser via BIAS-T.

[0006] Non-Patent Document 2, a paper by G.H. Smith, D. Novak, and Z. Ahmed published in International Topical Meeting on Microwave Photonics. MWP'96 Technical Digest. Satellite Workshop (Cat. No. 96TH8153), 1996, pp. 5-8 suppl., DOI: 10.1109 / MWP.1996.660352, describes a known technology for generating an optical signal using an electro-optic modulator, in which the optical signal is modulated using an electrical signal.

[0007] A similar configuration is known technology described in Non-Patent Document 3, a paper by Y. Cui, K. Xu, Y. Dai, and J. Lin, published in 2012 IEEE International Topical Meeting on Microwave Photonics, 2012, p103-106, DOI: 10.1109 / MWP.2012.6474066, where a pseudo-differential optical output is provided.

[0008] According to Non-Patent Document 4, a paper by X. S. Y. Ao and L. Maleki published in IEEE Journal of Quantum Electronics, vol. 32, no. 7, pp. 1141-1149, July 1996, DOI: 10.1109 / 3.517013, a system for modulating an optical signal using an optical modulator is known. The optical output signal of the modulator is converted into an electrical signal by a photodiode, amplified and filtered, and then becomes the control signal for the modulator. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Stephens, W.E. and Joseph, T.R. “System characteristics of direct modulated and externally modulated RF fiber-optic links” J. Lightwave Technol., vol. 5, p380, DOI: 10.1109 / JLT.1987.1075509 [Non-Patent Document 2] G.H. Smith, D. Novak; and Z. Ahmed, “Novel technique for generation of optical SSB with carrier using a single MZM to overcome fibre chromatic dispersion” International Topical Meeting on Microwave Photonics. MWP‘96 Technical Digest. Satellite Workshop (Cat. No. 96TH8153), 1996, p5 - 8 suppl., DOI: 10.1109 / MWP.1996.660352 [Non-Patent Document 3] Y. Cui, K. Xu, Y. Dai and J. Lin, “Suppression of second-order harmonic distortion in ROF links utilizing dual-output MZM and balanced detection” 2012 IEEE International Topical Meeting on Microwave Photonics, 2012, p103 - 106, DOI: 10.1109 / MWP.2012.6474066 [Non-Patent Document 4] X.S. Yao and L. Maleki, “Opto-electronic oscillator for photonic systems” IEEE Journal of Quantum Electronics, vol. 32, no. 7, p1141 - 1149, July 1996, DOI: 10.1109 / 3.517013 Summary of the Invention [Problem to be solved by the invention]

[0010] However, previous solutions are essentially characterized in that the optical signal is generated using an external signal generator, the output signal of which is used to modulate the optical signal.

[0011] It should also be noted that multiple identical optical signals can only be generated using optical power splitters or multiple optical sources and modulators.

[0012] In the case of an optical power divider, the optical power in each branch is reduced by a factor of 1 / N, where N is the division ratio. Nevertheless, to obtain a sufficiently high optical power in each branch, either the light source must provide an arbitrary amount of optical power (which is not practical), or an arbitrary number of light sources in the optical domain must be phase- and frequency-locked.

[0013] Frequency locking can be achieved, for example, by using thermal elements, but this increases the power dissipation of the system. Phase locking requires additional optical phase shifters, and the additional hardware adds significantly to the complexity, cost, and size of the system overall.

[0014] It is also important to note that electro-optic modulators can only operate up to a maximum optical input power, beyond which they will be destroyed, so such a solution is only applicable in certain circumstances.

[0015] When multiple light sources and modulators are used, additional electrical amplifiers may be required to amplify the signal from the electrical signal generator. This increases the power loss of the system and the phase noise of the signal. Furthermore, optical modulators have nonlinear characteristics that generate additional harmonics of the desired signal to be distributed. Furthermore, separate optical modulators are very expensive, while integrated optical modulators have high attenuation and high assembly costs.

[0016] Therefore, this solution is also impractical.

[0017] Furthermore, the optical modulator is biased to obtain maximum linearity at the 3 dB point (quadrature point).

[0018] However, this results in a 3 dB loss of signal power, which is not available in the optical path.

[0019] Recognizing the above drawbacks, it is an object of the present invention to provide an improvement that provides higher performance at reasonable manufacturing costs.

[0020] Brief description of the invention The object of the invention is achieved by an electro-optical mixer having an electrical output according to claim 1. Further advantageous configurations of the invention are the subject of the dependent claims, the description and the drawings. [Brief explanation of the drawings]

[0021] Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which: [Figure 1] 1 is a first block diagram abstracted from an embodiment of the present invention; [Figure 2] FIG. 2 is a second block diagram abstracted from another embodiment of the present invention. [Figure 3] 1 is a schematic diagram of one embodiment of the present invention based on a cross-coupled LC oscillator. [Figure 4] 1 is a schematic diagram of one embodiment of the present invention based on a cross-coupled LC oscillator. [Figure 5] 1 is a schematic diagram of one embodiment of the present invention based on a cross-coupled LC oscillator. [Figure 6] 1 is a schematic diagram of one embodiment of the present invention based on a Colpitts oscillator. [Figure 7] 1 is a schematic diagram of one embodiment of the present invention based on a Colpitts oscillator. [Figure 8] 1 is a schematic diagram of one embodiment of the present invention based on a Colpitts oscillator. [Figure 9]1 is a schematic diagram of one embodiment of the present invention based on a Clapp oscillator. [Figure 10] 1 is a schematic diagram of one embodiment of the present invention based on a ring oscillator. [Figure 11] Schematic diagram of an inverter gate implementation. [Figure 12] 1 is a schematic diagram of an embodiment of the present invention based on a YIG oscillator. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will now be described in more detail with reference to the figures, where it is noted that different aspects are described which can be used either alone or in combination, i.e. each aspect can be used in different embodiments of the invention, unless expressly indicated as pure alternatives.

[0023] Furthermore, for simplicity of description, reference will generally be made hereinafter to only one entity. However, unless expressly stated otherwise, the present invention may include multiple entities. To that extent, the use of the singular term "one" should be understood only to indicate that at least one entity is used in an embodiment.

[0024] Insofar as methods are described below, the individual steps of the methods can be arranged and / or combined in any order unless the context explicitly dictates otherwise. Furthermore, unless otherwise stated, these methods can be combined with each other.

[0025] Information containing numerical values ​​should generally not be understood as exact values ​​but may include a tolerance of + / -1% to + / -10%.

[0026] References to standards or specifications should be understood as references to the standards or specifications that are / were in force at the time of filing the application and / or to which priority is claimed, i.e. at the time of the priority application, but should not be understood as a general exclusion of applicability to subsequent or superseding standards or specifications.

[0027] 1 to 12 show various embodiments of the present invention. What these have in common is that the present invention shows an optoelectronic oscillator 1. This optoelectronic oscillator 1 has at least one electrical-optical conversion unit LD1 and one optoelectronic conversion unit PD1.

[0028] During operation, the photoelectric oscillator 1 can modulate the light emitted from the electro-optical conversion unit LD1. During operation, a portion of the light from the electro-optical conversion unit LD1 is irradiated onto the optoelectric conversion unit PD1, and a modulated electrical signal is generated within the optoelectronic conversion unit PD1 by the light irradiated from the electro-optical conversion unit LD1. This modulated electrical signal is used to control the modulation of the light emitted from the electro-optical conversion unit LD1 during operation, resulting in the generation of an oscillation during operation.

[0029] 1 illustrates a first block diagram according to the present invention. A system having a control loop (electrical) transfer function H(jω) and / or (optical) transfer function G(jω) controls control signals in the signal paths of one or more light sources and / or optical modulators LD1 to LDN. These light sources and / or optical modulators LD1 to LDN can be interconnected as needed, for example (partially) connected in series or (partially) connected in parallel. It is also possible to interconnect a combination of these two circuit topologies.

[0030] The optical output signals ψ from the light sources and / or optical modulators LD1 to LDN become the output signals of the system.

[0031] The control circuit can be closed by an electrical signal and / or an optical signal.

[0032] If the (electrical) transfer function H(jω) and / or the (optical) transfer function of the control loop are appropriately selected, the oscillation conditions are met and the optical signal oscillates.

[0033] In general, a modulatable light source can be designed as either a directly modulatable light source or an indirectly modulatable light source. An indirectly modulatable light source can, for example, have a light source that continuously emits light independently of the modulation, which is modulated by a modulator M. For example, a continuous wave laser diode can be used in combination with a modulator.

[0034] 2 illustrates a second block diagram according to the present invention. A system with an open (electrical) control loop transfer function H(jω) and / or an (optical) control loop transfer function (jω) controls the control signals of one or more light sources and / or optical modulators LD1 to LDN. These light sources and / or optical modulators LD1 to LDN can be interconnected as required, for example (partially) in series, (partially) in parallel, or as a combination of these two circuit topologies.

[0035] The optical output signals of the light sources and / or optical modulators LD1 to LDN, or a portion (1-c)ψ of the output signals of the light sources and / or optical modulators, are optically connected via an optical channel to a photodiode PD1 connected to the input of the control loop, thereby closing the control loop.

[0036] If the (electrical) transfer function H(jω) and / or the (optical) transfer function G(jω) are appropriately selected and the optical system is sufficiently coupled, the oscillation conditions are met and the optical signal oscillates.

[0037] 3 to 11 show embodiments of the present invention. It should be noted that these embodiments are merely examples and are used to illustrate the functional schematic diagram, but the functional schematic diagram is not limited to these embodiments.

[0038] For example, the electrical-to-optical conversion can be implemented using modulated light sources and / or optical modulators LD1 to LDN.

[0039] In particular, the (directly) modulated light sources LD1 to LDN can be implemented as LEDs or lasers. Alternatively, a continuously emitting light source can be combined with an optical modulator to be used as a modulated light source LD1 to LDN.

[0040] In particular, in some embodiments, the light emitted from the light source during operation can be configured to be modulatably controlled by a controllable modulator M.

[0041] In embodiments of the present invention, the modulator M may be implemented as an intensity modulator, a Mach-Zehnder modulator, or a ring modulator.

[0042] In other embodiments, the electrical-optical converters PD1, PD2 can be implemented as optical antennas and / or photodiodes and / or phototransistors.

[0043] In some configurations of the present invention, the optoelectronic oscillator 1 can be implemented as a cross-coupled LC oscillator, as illustrated in Figures 3 to 5. Here, Figures 3 to 5 essentially differ in that the light sources and / or optical modulators LD1, LD2 are arranged in different ways. However, instead of one light source and / or optical modulator LD1, any number of light sources LD1 to LDN can also be used. In particular, the light sources in the emitter branches of Figure 5 can also be used for feedback.

[0044] In another alternative configuration of the present invention, the optoelectronic oscillator 1 can be implemented as a Colpitts oscillator, as illustrated in FIGS.

[0045] In another alternative configuration of the present invention, the optoelectronic oscillator 1 may be implemented as a Clapp oscillator, as illustrated in FIG.

[0046] In yet another alternative configuration of the present invention, the optoelectronic oscillator 1 may be implemented as a ring oscillator, as illustrated in Figure 10. In particular, the ring oscillator may include inverter gates, as shown in Figure 12.

[0047] In a further alternative configuration of the invention, the optoelectronic oscillator 1 can also be designed as a YIG oscillator, as illustrated in FIG.

[0048] The present invention allows for the arrangement of a plurality of electro-optical converting units LD2 to LDN each including an optoelectronic oscillator 1 and controlled by the optoelectronic oscillator 1, without loss of generality.

[0049] In particular, at least some of the electrical-optical conversion units may be connected in parallel or in series.

[0050] Without limiting generality, the optoelectronic oscillator 1 of the present invention can be constructed not only in a fully integrated form, but also in a partially integrated form, i.e., a form including at least partially discrete components, and a form using only discrete components.

[0051] Some embodiments of the present invention are further configured to allow the output frequency, or the frequency of the envelope of the optoelectronic oscillator 1, or the frequency of the optical output signal of the optoelectronic oscillator 1 to be adjustable.

[0052] According to other embodiments, the tunability of the optoelectronic oscillator (1) can be implemented by electrical and / or optical components.

[0053] In particular, the tuning functionality of the optoelectronic oscillator 1 can be implemented by a tunable resonator, and / or a phase shifter, and / or a capacitor, and / or a coil, and / or a delay line, and / or a frequency shifter, and / or an optical modulator M.

[0054] In particular, in the case of frequency tuning by an optical modulator, the optical modulator can be implemented as an intensity modulator, a Mach-Zehnder modulator, or a ring modulator.

[0055] The resonators shown in the figures can also be constructed as particularly tenable resonators.

[0056] Additionally, the optical signal ψ can be split and sent to different locations at lower powers.

[0057] The present invention makes it possible to generate an optical output signal without using an external signal source, for which purpose an optical return channel without an optical modulator is used, whereby the light sources and / or the optical modulators LD1 to LDN are directly modulated by the system.

[0058] Directly modulating the light source means that no additional costly components such as modulators are required.

[0059] Furthermore, any number of light sources and / or optical modulators LD1 to LDN can be cascaded or connected in parallel, and any number of paths that can utilize the maximum laser power can be secured. If the optical amplitude and / or extinction ratio of the light sources and / or optical modulators LD1 to LDN is too large, the output signal from each light source can be divided again into an appropriate number of paths.

[0060] In the case of a differential oscillator structure, the optical signal is also pseudo-differential.

[0061] Due to its simple and robust design, the invention is also suitable for demanding environmental conditions, and in particular can be used in radar systems, for example in the vehicle field.

Claims

1. An optoelectronic oscillator (1) comprising at least one electrical-optical conversion unit (LD1) and one optoelectronic conversion unit (PD1), The light that can be emitted by the electrical-optical conversion unit (LD1) during operation can be modulated, and during operation, a portion of the light from the electrical-optical conversion unit (LD1) is irradiated onto the optoelectronic conversion unit (PD1), and a modulated electrical signal generated in the optoelectronic conversion unit (PD1) by the irradiated light from the electrical-optical conversion unit (LD1) is used to control the modulation of the light that can be emitted from the electrical-optical conversion unit (LD1) during operation, forming an optoelectronic oscillator that generates oscillation during operation.

2. An optoelectronic oscillator (1) according to claim 1, characterized in that the electrical-optical conversion is performed by means of a modulated light source (LD1 to LDN) and / or an optical modulator (M).

3. An optoelectronic oscillator (1) according to claim 1 or claim 2, characterized in that the directly modulated light sources (LD1 to LDN) are implemented as LEDs and / or lasers.

4. An optoelectronic oscillator (1) according to any one of claims 1 to 3, characterized in that the electrical-optical conversion unit (LD1) has a modulator (M), and the modulator (M) is implemented as an intensity modulator.

5. An optoelectronic oscillator (1) according to claim 4, characterized in that the modulator (M) is implemented as a Mach-Zehnder modulator or a ring modulator.

6. An optoelectronic oscillator (1) according to claim 1, characterized in that the electrical-to-optical conversion (LD1-LDN) is performed by means of an optical antenna.

7. An optoelectronic oscillator (1) according to claim 1, characterized in that the optoelectronic conversion (PD1) is performed by means of a photodiode, a phototransistor or an optical antenna.

8. An optoelectronic oscillator (1) according to any one of claims 1 to 7, characterized in that the optoelectronic oscillator (1) is implemented as a cross-coupled LC oscillator, a Colpitts oscillator, a Clapp oscillator or a ring oscillator, or the optoelectronic oscillator (1) is designed as a YIG oscillator.

9. An optoelectronic oscillator (1) according to claim 5, characterized in that the ring oscillator comprises an inverter gate.

10. An optoelectronic oscillator (1) according to any one of claims 1 to 9, comprising an arrangement of a plurality of electrical-optical conversion units (LD2 to LDN), the plurality of electrical-optical conversion units (LD2 to LDN) being controlled by the optoelectronic oscillator (1).

11. An optoelectronic oscillator (1) according to claim 10, characterized in that at least some of the plurality of electro-optical units are connected in parallel.

12. An optoelectronic oscillator (1) according to claim 10, characterized in that at least some of the plurality of electro-optical units are connected in series.

13. An optoelectronic oscillator (1) according to any one of claims 1 to 12, characterized in that the optoelectronic oscillator (1) is built up from individual components.

14. An optoelectronic oscillator (1) according to any one of claims 1 to 13, characterized in that the optoelectronic oscillator (1) is partially integrated or fully integrated.

15. An optoelectronic oscillator (1) according to any one of claims 1 to 14, characterized in that the output frequency of the optoelectronic oscillator (1), or the frequency of the envelope of the optoelectronic oscillator (1), or the frequency of the optical output signal of the optoelectronic oscillator (1) can be tuned.

16. An optoelectronic oscillator (1) according to any one of claims 1 to 15, characterized in that tuning of the optoelectronic oscillator (1) is performed by means of electrical components or by means of optical components.

17. An optoelectronic oscillator (1) according to any one of claims 1 to 16, characterized in that tuning of the optoelectronic oscillator (1) is performed by means of an adjustable resonator, a phase shifter, a capacitor, a coil, a delay line or a frequency shifter.

18. An optoelectronic oscillator (1) according to any one of claims 1 to 17, characterized in that tuning of the optoelectronic oscillator (1) is performed by an optical modulator (M).

19. An optoelectronic oscillator (1) according to any one of claims 1 to 18, characterized in that the modulator (M) of the optoelectronic oscillator (1) is implemented as an intensity modulator, a Mach-Zehnder modulator or a ring modulator.

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