OPTICALLY BASED ANALOG-DIGITAL CONVERTER

Abstract

The invention relates to an optically-based analogue-to-digital converter comprising: a first combiner with a first input for an optical reference signal, and a second input for an input signal that is to be digitised, a second combiner with a first input for a pulsed laser signal, and a second input, which is connected to the output of the first combiner, an evaluation unit, which evaluates the output signal of the second combiner s.

Claims

1. An optically-based analogue-to-digital converter comprising: a first combiner with a first input for an optical reference signal (Ref) and a second input for an input signal that is to be digitised, a second combiner with a first input for a pulsed laser signal, and a second input, which is connected to the output of the first combiner, an evaluation unit, which evaluates the output signal of the second combiner s.

2. The optically-based analogue-to-digital converter in accordance with claim 1, wherein an optical modulator is arranged ahead of the input for the input signal that is to be digitised, which electro-optical modulator modulates an optical input signal by means of the input signal that is to be digitised.

3. The optically-based analogue-to-digital converter in accordance with claim 1, wherein an electro-optical modulator (MOD) is arranged ahead of the input for the input signal that is to be digitised, which electro-optical modulator modulates an optical input signal by means of the input signal that is to be digitised, wherein the input signal that is to be digitised is an electrical signal.

4. The optically-based analogue-to-digital converter in accordance with claim 3, wherein a first splitter is arranged ahead of the electro-optical modulator, which splits an optical input signal, wherein a first part of the optical input signal is made available to the electro-optical modulator while operation is in progress, and a second part of the optical input signal is fed to the first input of the first combiner as a reference signal (Ref) while operation is in progress.

5. The optically-based analogue-to-digital converter in accordance with claim 1, wherein an RF laser is arranged ahead of the input for the input signal that is to be digitised, which RF laser is controlled by means of the input signal that is to be digitised, wherein the input signal that is to be digitised is an electrical signal.

6. The optically-based analogue-to-digital converter in accordance with claim 1, wherein the optical reference signal (Ref) is provided by a second CW laser.

7. The optically-based analogue-to-digital converter in accordance with claim 1, wherein a pulse shaper is arranged ahead of the input for the pulsed laser signal.

8. The optically-based analogue-to-digital converter in accordance with claim 7, wherein the input signal for the pulse shaper is provided by a pulsed laser, or by a first CW laser followed by a pulse shaper.

9. The optically-based analogue-to-digital converter in accordance with claim 7, wherein a second splitter is arranged directly ahead of the pulse shaper, wherein a first part of the optical input signal to the second splitter is made available to the pulse shaper while operation is in progress, and a second part of the optical input signal is fed to the first input of the first combiner as a reference signal via an optical parametric oscillator (while operation is in progress.

10. The optically-based analogue-to-digital converter in accordance with claim 1, wherein the evaluation unit has a quantum pulse gate.

11. The optically-based analogue-to-digital converter in accordance with claim 10, wherein the quantum pulse gate is a multi-output quantum pulse gate.

12. The optically-based analogue-to-digital converter in accordance with claim 10, wherein the quantum pulse gate has a poled non-linear waveguide.

13. The optically-based analogue-to-digital converter in accordance with claim 10, wherein the quantum pulse gate has a poled lithium niobate waveguide, and/or a poled potassium titanyl phosphate waveguide.

14. The optically-based analogue-to-digital converter in accordance with claim 11, wherein the non-linear waveguide is periodically poled.

15. The optically-based analogue-to-digital converter in accordance with claim 11, wherein the non-linear waveguide is aperiodically poled.

16. The optically-based analogue-to-digital converter in accordance with claim 10, wherein the evaluation unit has at least one optoelectronic wall unit.

17. The optically-based analogue-to-digital converter in accordance with claim 1, wherein the evaluation unit has a first optical bandpass filter.

18. The optically-based analogue-to-digital converter in accordance with claim 1, wherein the optical-based analogue-to-digital converter is fully integrated.

19. The optically-based analogue-to-digital converter in accordance with claim 1, wherein the optically-based analogue-to-digital converter is at least partially integrated.

20. The optically-based analogue-to-digital converter in accordance with claim 1, wherein the optically-based analogue-to-digital converter is implemented with discrete components.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention is explained in more detail below with reference to the figures. In these:

[0014] FIG. 1 shows schematically the basic principle of the quantum-assisted ADU in accordance with forms of embodiment of the invention,

[0015] FIG. 2 shows schematically the basic principle of the quantum-assisted ADU in accordance with forms of embodiment of the invention for an electrical input signal,

[0016] FIG. 3 shows schematically the basic principle of the quantum-assisted ADU in accordance with forms of embodiment of the invention, in which the reference signal is generated on the basis of the pulsed laser signal,

[0017] FIG. 4 shows schematically the basic principle of the quantum-assisted ADU in accordance with forms of embodiment of the invention for an electrical input signal, wherein both the reference signal and the input signal of the EO converter can be generated by means of OPO using the pulsed laser signal,

[0018] FIG. 5 shows schematically the basic principle of the quantum-assisted ADU in accordance with forms of embodiment of the invention with CW laser and pulse-forming element, and

[0019] FIG. 6 shows schematically the basic principle of the quantum-assisted ADU in accordance with forms of embodiment of the invention for an electrical input signal. Here, the input signal of the OE modulator and the reference signal originate from the same source.

DETAILED DESCRIPTION

[0020] In what follows, the invention will be described in more detail with reference to the figures. It should be noted that different aspects are described, each of which can be used individually or in combination. In other words, each aspect can be used with different forms of embodiment of the invention, unless explicitly shown as a pure alternative.

[0021] Furthermore, in what follows, for the sake of simplicity, reference will generally only be made to one entity. Unless explicitly stated, however, the invention may also comprise a plurality of the entities concerned. In this respect, the use of the word one is only to be understood as an indication that at least one entity is used in a simple form of embodiment.

[0022] Insofar as methods are described in what follows, the individual steps of a method can be arranged and/or combined in any order, unless the context explicitly indicates otherwise. Furthermore, the methods can be combined with each other, unless expressly indicated otherwise.

[0023] Data with numerical values are generally not to be understood as exact values, but also include a tolerance from +/1% up to +/10%.

[0024] References to standards or specifications are to be understood as references to standards or specifications in force at the time of the application and/orif priority is claimedat the time of the priority application. However, this is not to be understood as a general exclusion of applicability to subsequent or superseding standards or specifications.

[0025] FIGS. 1-6 show exemplary forms of embodiment of the invention.

[0026] In forms of embodiment of the invention, an optically-based analogue-to-digital converter 1 is provided.

[0027] The basic principle of the invention is shown in FIG. 1, and operates in accordance with the principle from the article Achieving the Ultimate Quantum Timing Resolution by the authors Vahid Ansari, Benjamin Brecht, Jano Gil-Lopez, John M. Donohue, Jaroslav Rehacek, Zdenek Hradil, Luis L. Snchez-Soto, and Christine Silberhorn, published in 2021-01 PRX Quantum, Vol. 2 American Physical Society p. 010301.

[0028] The optically-based analogue-to-digital converter 1 in accordance with the invention has a first combiner C1 with a first input I1 for an optical reference signal (Ref), and a second input I2 for an input signal (Analogue) that is to be digitised.

[0029] Furthermore, the optically-based analogue-to-digital converter 1 in accordance with the invention has a second combiner C2 with a first input I3 for a pulsed laser signal, and a second input 14, which is connected to the output of the first combiner C1.

[0030] In addition, the inventive optically-based analogue-to-digital converter 1 has an evaluation unit AE, which evaluates the output signal of the second combiner C2.

[0031] In the invention, two optical signals, the reference signal (Ref) and the analogue signal (that is to be digitised) are superposed in the first combiner C1 while operation is in progress. Here the amplitude of the reference signal is known.

[0032] This superposition of the two input signals is fed into an evaluation unit AE, together with a shaped pulse. The output signal of the evaluation unit AE can then be used to draw conclusions concerning the differences in intensity.

[0033] The value of the analogue signal can be determined by evaluating the measured signal and the reference signal, which is already known.

[0034] The pulsed laser signal can be used to provide a clock for temporal quantisation.

[0035] In forms of embodiment of the invention, see for example FIG. 2, 3 or 6, an optical modulator MOD is arranged ahead of the input for the input signal that is to be digitised; the modulator modulates an optical input signal by means of the input signal that is to be digitised.

[0036] In one form of embodiment of the invention, an electro-optical modulator MOD is arranged ahead of the input I2 for the input signal that is to be digitised; the modulator modulates an optical input signal by means of the input signal that is to be digitised, wherein the input signal that is to be digitised is an electrical signal.

[0037] That is to say, if the analogue signal that is to be digitised is present as an electrical signal, the electrical signal can be converted into an optical signal using the optical modulator MOD. The design of the optical modulator can be selected in an appropriate manner by a person skilled in the art.

[0038] In the form of embodiment in accordance with FIG. 3, a first splitter SP1 is arranged ahead of the electro-optical modulator MOD; the splitter splits an optical input signal, wherein a first part of the optical input signal is made available to the electro-optical modulator MOD while operation is in progress, and a second part of the optical input signal is fed to the first input I1 of the first combiner C1 as the reference signal Ref while operation is in progress.

[0039] In one form of embodiment of the inventionsee FIGS. 3 and 4the reference signal can also be generated by means of an optical parametric oscillator OPO based on the pulsed laser signal of the source PL. In one form of embodiment, both the reference signal and the input signal of the EO modulator MOD can be generated by means of an optical parametric oscillator OPO based on the pulsed laser signal PL.

[0040] In accordance with a further form of embodiment of the invention, an RF laser is arranged ahead of the input I2 for the input signal that is to be digitised; the laser is controlled by means of the input signal that is to be digitised, wherein the input signal that is to be digitised is an electrical signal.

[0041] That is to say, it is also possible to convert an analogue electrical signal that is to be digitised directly into an optical signal using an RF laser.

[0042] In accordance with yet another form of embodiment of the inventionsee FIG. 2the optical reference signal Ref can also be provided by a second CW laser CW2.

[0043] In one form of embodiment of the inventionsee figuresa pulse shaper PS can be arranged ahead of the input I3 for the pulsed laser signal.

[0044] In yet another form of embodiment of the invention, the input signal for the pulse shaper PS is provided by a pulsed laser PLsee FIGS. 1-4 and 6or by a first CW laser CW1 followed by a pulse shaper PFsee FIG. 6.

[0045] In accordance with a further form of embodiment of the invention, a second splitter SP2 is arranged directly ahead of the pulse shaper PSsee FIGS. 3 and 4wherein a first part of the optical input signal from the second splitter SP2 is made available to the pulse shaper PS while operation is in progress, and a second part of the optical input signal is fed to the first input I1 of the first combiner C1 as a reference signal Ref via an optical parametric oscillator OPO while operation is in progress.

[0046] In accordance with yet another form of embodiment of the invention, the evaluation unit AE has a quantum pulse gate QPG. In particular, the quantum pulse gate QPG can also be a multi-output quantum pulse gate.

[0047] Similarly, in one form of embodiment of the invention, the quantum pulse gate QPG can be provided with a polarised non-linear waveguide. The polarisation can be both periodic and aperiodic.

[0048] In a further form of embodiment of the invention, the quantum pulse gate QPG has a periodically polarised lithium niobate waveguide, or a polarised potassium titanyl phosphate waveguide. The polarisation can be both periodic and aperiodic.

[0049] Furthermore, in one form of embodiment of the invention, provision can be made for the evaluation unit Ae to comprise at least one optoelectronic conversion unit OE, e.g. a photodiode or a phototransistor.

[0050] In a further form of embodiment of the invention, the evaluation unit AE further comprises a first optical bandpass filter BP1.

[0051] In accordance with yet another embodiment, the optically-based analogue-to-digital converter 1 is fully integrated, or partially integrated, or designed with discrete components.

[0052] The invention provides an analogue-to-digital converter that makes it possible to digitise any analogue optical and electrical signals with high resolution accuracy, low distortion and low internal noise.

[0053] The inventive analogue-to-digital converter is limited in its resolution accuracy solely by the quantum noise. This means that the disadvantages of the current state of the art in terms of resolution accuracy can be overcome. In addition, the ADU can also be used for quantum applications without the need to be cooled down to cryogenic temperatures.