Optoelectronic oscillator

Abstract

The invention relates to an optoelectronic oscillator (1) comprising at least one electro-optical conversion unit (LD1), which emits light that can be modulated during operation, and a photoelectric conversion unit (PD1), on which part of the light from the electro-optical conversion unit (LD1) impinges during operation, and on which part of the light from the electro-optical conversion unit (LD1) impinges on the photoelectric conversion unit (PD1). Light irradiated by the electro-optical conversion unit (LD1) generates a modulation electric signal in the photoelectric conversion unit (PD1), and the modulation electric signal is used for controlling modulation of light emitted by the electro-optical conversion unit (LD1) to form oscillation during operation.

Description

Technical Field

[0001] The present invention relates to a photoelectric oscillator. Background Art

[0002] With increasing digitalization, the demand for systems with optical clock distribution or optical signal distribution is also growing; these systems require a certain average signal power with a specific optical modulation at different spatial points.

[0003] Currently, in most cases this is achieved by using a laser with a subsequent electro-optical modulator and possibly an optical beam splitter.

[0004] While it is possible to build such a system using discrete components, this approach is costly and energy-intensive because the modulator requires biasing at any operating point. Furthermore, an external electronic signal generator is required to control the modulator.

[0005] For example, in the article "System Characterization of Directly and Externally Modulated Radio Frequency Fiber Links," published in the Journal of Lightwave Technology, Volume 5, page 380, DOI: 10.1109 / JLT.1987.1075509, Stephens, WE, and Joseph, TR, disclose a prior art system in which an optical signal is generated by modulating the current of a laser diode. The modulation signal itself is generated by an external source. Finally, an electrical control signal is added to the laser's DC current via a bias-T.

[0006] In the article "A New Technique for Overcoming Fiber Dispersion by Generating Optical Single-Sideband with a Carrier Using a Single MZM," published by G.H. Smith, D. Novak, and Z. Ahmed in the 1996 International Conference on Microwave Photonics Technical Digest Satellite Symposium (No. 96TH8153), pp. 5-8, DOI: 10.1109 / MWP.1996.660352, a prior art system is disclosed in which an optical signal is generated by an electro-optical modulator. The optical signal is then modulated using an electrical signal.

[0007] A similar device, in which a pseudo-differential optical output is provided, is disclosed in the article “Second-order harmonic distortion suppression in RoF links using dual-output MZM and balanced detection,” published by Y. Cui, K. Xu, Y. Dai, and J. Lin in the 2012 IEEE International Symposium on Microwave Photonics, pp. 103-106, DOI: 10.1109 / MWP.2012.6474066.

[0008] XS Yao and L. Maleki, in their article "Optoelectronic Oscillators for Photonic Systems," published in the July 1996 IEEE Journal of Quantum Electronics, Vol. 32, No. 7, pp. 1141-1149 (DOI: 10.1109 / 3.517013), disclose a prior art system in which an optical signal is modulated by an optical modulator. The modulator's optical output signal is converted to an electrical signal by a photodiode, amplified, and filtered, and then becomes the modulator's control signal.

[0009] However, a key feature of the solutions to date is that the optical signal is generated using an external signal generator, the output signal of which is used to modulate the optical signal.

[0010] It should also be noted that multiple identical optical signals can only be generated using optical power splitters or multiple light sources and modulators.

[0011] In the case of an optical power splitter, the power in each branch is reduced by a factor of 1 / N, where N is the splitting ratio. To still achieve sufficiently high optical power in each branch, either the light source must provide an arbitrary amount of power (which is not feasible) or an arbitrary number of light sources in the optical domain must be phase- and frequency-locked.

[0012] For example, frequency locking can be achieved using thermal elements that increase system power dissipation. Phase locking requires additional optical phase shifters. Overall, the additional hardware significantly increases system complexity, cost, and size.

[0013] It should also be mentioned that electro-optic modulators only work up to a maximum optical input power and are damaged above this level. Therefore, this solution is only feasible in certain situations.

[0014] In the case of multiple optical sources and modulators, additional electrical amplifiers may be required to amplify the signal from the electrical signal generator. This in turn increases system power loss and increases the signal's phase noise. Furthermore, due to their nonlinear characteristics, optical modulators generate additional harmonics of the desired distributed signal. Furthermore, discrete optical modulators are very expensive, while integrated optical modulators have high attenuation and high assembly costs.

[0015] Therefore, this solution is also impractical.

[0016] Additionally, the EO modulator is biased at the 3dB point (quadrature point) for maximum linearity.

[0017] However, this results in a loss of 3 dB of signal power, which is not available in the optical path. Summary of the Invention

[0018] In view of the above disadvantages, the present invention aims to provide an improved solution to achieve higher performance at a moderate manufacturing cost.

[0019] The invention achieves this object by an electro-optical hybrid with an electrical output, an optoelectronic oscillator as claimed in claim 1. Further advantageous configurations of the invention are defined by the dependent claims, the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following describes the embodiments of the present invention in an exemplary manner with reference to the accompanying drawings, in which: Figure 1 is a first block diagram abstracted from one embodiment of the present invention, Figure 2 This is a second block diagram abstracted from another embodiment of the present invention. Figure 3-5 are schematic diagrams of an embodiment of the present invention based on a cross-coupled LC oscillator, Figure 6-8 are schematic diagrams of embodiments of the present invention based on a Colpitt oscillator, Figure 9 is a schematic diagram of an embodiment of the present invention based on a Clapp oscillator, Figure 10 is a schematic diagram of an embodiment of the present invention based on a ring oscillator, Figure 11 A schematic diagram for an inverter gate implementation; and Figure 12 Schematic diagram of an embodiment of the present invention based on a YIG (yttrium iron garnet) oscillator. DETAILED DESCRIPTION

[0021] The present invention is described in more detail below with reference to the accompanying drawings. It should be noted that different aspects are described below, and each aspect can be used alone or in combination. In other words, unless expressly stated as a pure alternative, each aspect can be used in combination with different embodiments of the present invention.

[0022] In addition, in the following text, usually only one entity is mentioned, unless otherwise explicitly stated, the present invention may also include multiple related entities. In this regard, the word "a" only means that at least one entity is used in a simple implementation form.

[0023] When describing method hereinafter, unless context clearly indicates otherwise, the individual steps of method can be arranged and / or combined in any order.In addition, unless otherwise clearly indicated, these methods can be combined with each other.

[0024] Generally speaking, data with numerical values should not be understood as exact values; rather, they should be understood to include a tolerance of + / - 1% to + / - 10%.

[0025] References to standards, codes or regulations should be understood as references to those applicable at the time of filing and / or, if priority is claimed, also to those applicable at the time of the priority application. This should not be construed as excluding the applicability of subsequent or superseding standards, codes or regulations.

[0026] Figures 1 to 12 Different embodiments of the present invention are shown. The common point of these embodiments is that the present invention shows an optoelectronic oscillator 1. The optoelectronic oscillator 1 includes at least one electro-optical conversion unit LD1 and one photoelectric conversion unit PD1.

[0027] When optoelectronic oscillator 1 operates, the light emitted from electro-optical conversion unit LD1 can be modulated. During operation, a portion of the light from electro-optical conversion unit LD1 is irradiated onto photoelectric conversion unit PD1, where a modulated electrical signal is generated in photoelectric conversion unit PD1. This modulated electrical signal is used to control the modulation of the light emitted from electro-optical conversion unit LD1 during operation, thereby forming an oscillation during operation.

[0028] Figure 1 A first exemplary block diagram of the present invention is shown. A system having an (electrical) control loop transfer function H(jω) and / or an (optical) control loop transfer function G(jω) controls control signals for one or any number of optical emission sources and / or optical modulators LD1...LDN. These optical emission sources and / or optical modulators LD1...LDN can be interconnected in any desired manner, such as partially in series, partially in parallel, or a combination of both topologies.

[0029] The optical output signal ψ of the optical emission source and / or the optical modulators LD1 . . . LDN is the output signal of the system.

[0030] The control loop can be closed by electrical and / or optical signals.

[0031] If the (electrical) transfer function H(jω) and / or the (optical) transfer function of the control loop are chosen appropriately, the oscillation conditions are met and the optical signal will oscillate.

[0032] Generally, a modulatable light emission source can be designed as a directly modulatable emission source or an indirectly modulatable emission source. An indirectly modulatable light emission source can, for example, have an emission source that emits light continuously, as opposed to modulated light, and be modulated by a modulator M. For example, a continuous wave laser diode can be used in conjunction with a modulator.

[0033] Figure 2A second exemplary block diagram of the present invention is shown. A system having an open (electrical) control loop transfer function H(jω) and / or an (optical) control loop transfer function controls control signals for one or any number of optical emission sources and / or optical modulators LD1...LDN. These optical emission sources and / or optical modulators LD1...LDN can be interconnected in any desired manner, such as partially in series, partially in parallel, or a combination of both topologies.

[0034] The optical output signal of one of the emission sources and / or optical modulators LD1...LDN, or a portion (1-c)ψ of the output signal of the optical emission source and / or optical modulator, is connected to the photodiode PD1 via an optical channel, and the photodiode PD1 is connected to the input of the control loop, thereby closing the control loop.

[0035] If the (electrical) transfer function H(jω) and / or the (optical) transfer function G(jω) are chosen appropriately (and the optical system is sufficiently coupled), the oscillation conditions are met and the optical signal will oscillate.

[0036] Figures 3 to 11 It should be noted that these implementations are only examples used to illustrate the functional block diagram, but the functional block diagram is not limited thereto.

[0037] For example, electro-optical conversion can be achieved by modulating the emission source and / or the optical modulators LD1...LDN. Specifically, the (direct) modulated sources LD1...LDN can be implemented using LEDs or lasers. A continuous light source with an optical modulator can also serve as the modulated sources LD1...LDN. In certain embodiments, the light emitted by the emission sources LD1...LDN during operation can be directly modulated, controlled by a modulated modulator M.

[0038] In the embodiment of the present invention, the modulator M may be designed as an intensity modulator, a Mach-Zehnder modulator or a ring modulator.

[0039] According to other forms of embodiment, the electro-optical conversion PD1 , PD2 may be implemented by an optical antenna and / or a photodiode and / or a phototransistor.

[0040] In some configurations of the present invention, the optoelectronic oscillator 1 can be designed as a cross-coupled LC oscillator, such as Figures 3 to 5 shown. Figures 3 to 5 The main difference is that the light sources and / or light modulators LD1, LD2 are arranged differently. However, in addition to one light source and / or one light modulator LD1, any number of light sources LD1...LDN can also be used. Specifically, in Figure 5 The light source in the middle emitter branch can also be used for feedback.

[0041] In an alternative configuration of the present invention, the optoelectronic oscillator 1 can be designed as a Colpitt oscillator, such as Figures 6 to 8 shown.

[0042] In another alternative configuration of the present invention, the optoelectronic oscillator 1 can also be designed as a Clapp oscillator, such as Figure 9 shown.

[0043] In another alternative configuration of the present invention, the optoelectronic oscillator 1 can also be designed as a ring oscillator, such as Figure 10 Specifically, the ring oscillator can have an inverting gate, such as Figure 12 shown.

[0044] According to a further alternative configuration of the present invention, the optoelectronic oscillator 1 can also be designed as a YIG oscillator, such as Figure 11 shown.

[0045] Without limiting the generality, the present invention is advantageous in arranging a plurality of electro-optical conversion units LD2...LDN having an optoelectronic oscillator 1 according to the present invention, wherein the plurality of electro-optical conversion units LD2...LDN are controlled by the optoelectronic oscillator 1, wherein at least some of the plurality of electro-optical conversion units can be connected in parallel or in series.

[0046] Without limiting the generality, the optoelectronic oscillator 1 of the present invention may be constructed not only in a fully integrated manner but also in a partially integrated manner, that is, at least partially using discrete components, or using only discrete components.

[0047] In the embodiment of the present invention, it is further provided that the output frequency of the optoelectronic oscillator 1 , or the frequency of the envelope, or the frequency of the optical output signal of the optoelectronic oscillator 1 is adjustable.

[0048] According to other forms of embodiment, the adjustability of the optoelectronic oscillator (1) can be achieved by electrical elements and / or optical elements.

[0049] Specifically, the adjustability of the optoelectronic oscillator 1 can be achieved through 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.

[0050] In particular, in the case of tuning via an optical modulator, the optical modulator can be designed as an intensity modulator, a Mach-Zehnder modulator, or a ring modulator.

[0051] The resonator shown in the figure can also be designed in particular as a tunable resonator. Furthermore, the optical signal ψ can be split in order to direct it to different locations (with lower intensity).

[0052] The present invention allows the generation of optical output signals without the need for an external signal source. In the context of the present invention, an optical return channel is used for this purpose without the need for an optical modulator. In this case, the light source and / or the optical modulators LD1 ... LDN are modulated directly by the system.

[0053] Directly modulating the optical emission source means that no additional costly components such as modulators are required.

[0054] Furthermore, any number of light sources and / or optical modulators LD1...LDN can be cascaded or connected in parallel to provide any number of paths with maximum laser power. If the optical amplitude and / or extinction ratio output by a light source and / or optical modulator LD1...LDN is too large, the output signal of each light source can be redistributed to an appropriate number of paths.

[0055] In the case of a differential oscillator structure, the optical signal is also pseudo-differential. Due to its simple and robust design, the present invention is suitable for environments with high environmental requirements. In particular, the present invention can be used in radar systems, such as vehicle-mounted radars.

Claims

1. A photoelectric oscillator (1), comprising at least one electro-optical conversion unit (LD1) and one photoelectric conversion unit (PD1), characterized in that: The electro-optical conversion unit (LD1) emits light that can be modulated during operation, wherein part of the light from the electro-optical conversion unit (LD1) is irradiated onto the photoelectric conversion unit (PD1) during operation, wherein the light irradiated by the electro-optical conversion unit (LD1) generates a modulated electrical signal in the photoelectric conversion unit (PD1), and the modulated electrical signal is used to control the modulation of the light emitted by the electro-optical conversion unit (LD1), thereby forming an oscillation during operation.

2. The optoelectronic oscillator (1) according to claim 1, characterized in that The electro-optical conversion is achieved by modulation sources (LD1...LDN) and / or optical modulators (M).

3. The optoelectronic oscillator (1) according to claim 1 and 2, characterized in that The modulation sources (LD1...LDN) are LEDs and / or lasers.

4. The optoelectronic oscillator (1) according to any one of the preceding claims, characterized in that The electro-optical conversion unit (LD1) has a modulator (M), and the modulator (M) is an intensity modulator.

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

6. The optoelectronic oscillator (1) according to claim 1, characterized in that The electrical-to-optical conversion (LD1 . . . LDN) is achieved via an optical antenna.

7. The optoelectronic oscillator (1) according to claim 1, characterized in that The photoelectric conversion (PD1) is achieved by a photodiode, a phototransistor or an optical antenna.

8. Optoelectronic oscillator (1) according to any one of the preceding claims, characterized in that The optoelectronic oscillator (1) is a cross-coupled LC oscillator, a Colpitt oscillator, a Clapp oscillator, a ring oscillator, or a YIG oscillator.

9. The optoelectronic oscillator (1) according to claim 5, characterized in that The ring modulator has an inverting gate.

10. A device having a plurality of electro-optical conversion units (LD2...LDN), characterized in that: The device comprises the optoelectronic oscillator (1) according to any one of the preceding claims, wherein the plurality of electro-optical conversion units (LD2 . . . LDN) are controlled by the optoelectronic oscillator (1).

11. The device according to claim 10, characterized in that At least some of the plurality of electro-optical conversion units are connected in parallel.

12. The device according to claim 10, characterized in that At least some of the plurality of electro-optical conversion units are connected in series.

13. The optoelectronic oscillator (1) according to any one of the preceding claims, characterized in that The photoelectric oscillator (1) is composed of discrete components.

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

15. The optoelectronic oscillator (1) according to any one of the preceding claims, characterized in that The output frequency of the optoelectronic oscillator (1), the envelope frequency of the optoelectronic oscillator (1) or the frequency of the optical output signal of the optoelectronic oscillator (1) are tunable.

16. Optoelectronic oscillator (1) according to any one of the preceding claims, characterized in that The tunability of the optoelectronic oscillator (1) is achieved through electrical elements or through optical elements.

17. The optoelectronic oscillator (1) according to any one of the preceding claims, characterized in that The tunability of the optoelectronic oscillator (1) is achieved through a tunable resonator, a phase shifter, a capacitor, a coil, a delay line or a frequency shifter.

18. The optoelectronic oscillator (1) according to any one of the preceding claims, characterized in that The tunability of the optoelectronic oscillator (1) is achieved through an optical modulator (M).

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

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