Optically based digital-to-analog converter

Abstract

The invention relates to an optically based digital-to-analog converter (1) comprising • A first pulse shaper (PS1) and a second pulse shaper (PS2), • A first combiner (C1) with a first input (I1) for a signal from the first pulse shaper (PS1) and a second input (I2) for another signal, • A second combiner (C2) with a first input (I3) for a signal from the second pulse shaper (PS2) and a second input (I4) for the further signal, • A first quantum pulse shaper (QPS1) and a second quantum pulse shaper (QPS2), • Where the first quantum pulse shaper (QPS1) receives the output signal of the first combiner (C1) during operation and the second quantum pulse shaper (QPS2) receives the output signal of the second combiner (C2) during operation, • A third combiner (C3) which, during operation, combines the output signals of the first quantum pulse shaper (QPS1) and the second quantum pulse shaper (QPS2), • an evaluation unit (AE) which evaluates the output signal of the third combiner (C3).

Description

[0001] The invention relates to an optically based digital-to-analog converter. background

[0002] Modern DACs are limited in their bandwidth by the bandwidth of their electrical components. To overcome this, nested architectures with multiplexers are used [1].

[0003] [1] E. Olieman, A.-J. Annema and B. Nauta, “An Interleaved Full Nyquist High-Speed ​​DAC Technique,” ​​in IEEE Journal of Solid-State Circuits, vol. 50, no. 3, pp. 704-713, March 2015, doi: 10.1109 / JSSC.2014.2387946.

[0004] These and similar solutions can only partially solve the problem of bandwidth limitation. To generate an arbitrarily high bandwidth, any number of DAC components must be interconnected. However, this solution cannot be expanded indefinitely, as the multiplexer eventually becomes the bandwidth-limiting element. While it is possible to use architectures with interconnected multiplexers, both interconnecting multiplexers and DAC components increases the complexity and the probability of failure of the entire DAC.

[0005] The system shown in [1] is limited in its bandwidth by the DAC components and multiplexers used. Furthermore, the nesting of the DAC components and multiplexers increases the overall complexity of the DAC, thus increasing the probability of failure and the DAC's power consumption.

[0006] In [2], a photonically assisted DAC was demonstrated that bypasses the multiplexer using Nyquist pulses. Thus, N DACs can be interconnected to generate almost arbitrarily high bandwidths.

[0007] [2] Christian Kress, Meysam Bahmanian, Tobias Schwabe, and J. Christoph Scheytt, “Analysis of the effects of jitter, relative intensity noise, and nonlinearity on a photonic digital-to-analog converter based on optical Nyquist pulse synthesis,” Opt. Express 29, 23671-23681 (2021)

[0008] Similar to the concept shown in [1], the concept shown in [2] also combines multiple DAC components to increase the bandwidth. As in [1], this increases the overall complexity of the DAC and thus the failure probability and energy consumption.

[0009] In [3] & [4] a DAC was shown which operates at cryogenic temperatures to realize the interface from classical electronics to a quantum computer.

[0010] [3] MEPV Zurita et al., “Cryogenic Current Steering DAC With Mitigated Variability,” in IEEE Solid-State Circuits Letters, vol. 3, pp. 254-257, 2020, doi: 10.1109 / LSSC.2020.3013443.

[0011] [4] MT Rahman, T. Lehmann, “A cryogenic DAC operating down to 4.2K,” Cryogenics, Volume 75, 2016, Pages 47-55, ISSN 0011-2275, https: / / doi.org / 10.1016 / j.cryogenics.2016.02.003.

[0012] The system shown in [3] and [4] operates at cryogenic temperatures and is therefore not suitable for mass market use. Furthermore, these DACs do not have any quantum support. The DACs shown in these works are intended to work only with a quantum system.

[0013] US patent application US 2021 / 0 278 746 A1 discloses an optical digital-to-analog converter with a 1:N splitter and a photodiode. A continuous laser signal is split using a splitter. One of the split light beams is combined with light from an N-bit optical DAC via a waveguide.

[0014] Although the known approaches represent an improvement, they are not able to solve the problems (internal noise as well as internal distortion) sustainably and cost-effectively, so that the resolution accuracy of the analog signal remains limited.

[0015] Based on this situation, the object of the invention is to provide an optically based analog-to-digital converter that enables the digitization of any desired high-resolution analog signals with high resolution accuracy, low distortion and low internal noise.

[0016] The object is achieved by an optically based digital-to-analog converter according to claim 1. Further advantageous embodiments are the subject matter of the dependent claims.

[0017] The invention is explained in more detail below with reference to the figures, which show: Fig. schematically different aspects of embodiments of an optically based digital-to-analog converter according to embodiments of the invention.

[0018] The invention will be described in more detail below with reference to the figures. It should be noted that various aspects are described, each of which can be used individually or in combination. This means that any aspect can be used with different embodiments of the invention unless explicitly presented as a mere alternative.

[0019] Furthermore, for the sake of simplicity, reference will generally only be made to one entity in the following. Unless explicitly stated, the invention may also comprise several of the entities in question. Therefore, the use of the words "a," "an," and "another" is to be understood merely as an indication that at least one entity is used in a simple embodiment.

[0020] Where procedures are described below, the individual steps of a procedure can be arranged and / or combined in any order, unless the context explicitly indicates otherwise. Furthermore, the procedures can be combined with one another unless expressly indicated otherwise.

[0021] Numerical values ​​are generally not to be understood as exact values ​​but also include a tolerance of + / - 1% up to + / - 10%.

[0022] References to standards or specifications are to be understood as references to standards or specifications that are / were in effect at the time of the application and / or, if priority is claimed, at the time of the priority application. However, this does not imply a general exclusion of applicability to subsequent or replacing standards or specifications.

[0023] Fig. show exemplary embodiments of the invention.

[0024] In embodiments of the invention, an optically based digital-to-analog converter 1 is provided.

[0025] The basic principle is in Fig. The optically based digital-to-analog converter 1 has a first pulse shaper PS1 and a second pulse shaper PS2, as well as a first combiner C1 with a first input I1 for a signal from the first pulse shaper PS1 and a second input I2 for a further signal, a second combiner C2 with a first input I3 for a signal from the second pulse shaper PS2 and a second input I4 for the further signal.

[0026] Furthermore, the optically based digital-to-analog converter 1 has a first quantum pulse shaper QPS1 and a second quantum pulse shaper QPS2.

[0027] During operation, the first quantum pulse shaper QPS1 receives the output signal of the first combiner C1 and the second quantum pulse shaper QPS2 receives the output signal of the second combiner C2.

[0028] In addition, the optically based digital-to-analog converter 1 has a third combiner C3, which combines the output signals of the first quantum pulse shaper QPS1 and the second quantum pulse shaper QPS2 during operation, and an evaluation unit AE, which evaluates the output signal of the third combiner C3.

[0029] In operation, an optical pulsed signal is split into two paths and then its spectral properties are modified using a pulse-shaping element. This pulse shaper can be controlled by a digital element. For example, Hermite Gaussian modes (HGMs) can be used.

[0030] These two signals, together with two further signals, which are also provided by splitting the light of a (second) source, are fed into two quantum pulse shapers QPS1, QPS2, which, for example, have a non-linear waveguide (PPPLN WG).

[0031] The nonlinear process in the quantum pulse shapers QPS1, QPS2 generates an output signal that has the desired spectral properties.

[0032] Heterodyne detection within an evaluation unit (AE), such as a detector, can generate an electrical signal proportional to the difference between the two optical signals. The number of HGMs used allows for the output signal to be finely resolved as desired.

[0033] The invention thus realizes a quantum-assisted DAC.

[0034] The optically based digital-to-analog converter 1 shown in this invention is only slightly limited in bandwidth by the surrounding electronic hardware. A "limitation"—if it could even be perceived as such (at least compared to previous approaches)—is essentially determined by the bandwidth of the evaluation unit AE.

[0035] However, photodiodes that can be used as detectors with a bandwidth of more than 300 GHz have already been shown in the literature, see for example the article “Over 300 GHz bandwidth UTC-PD module with 600 GHz band rectangular-waveguide output” by the authors T. Kurokawa, T. Ishibashi, M. Shimizu, K. Kato, & T. Nagatsuma, published in Electronics Letters, 2018, 54, pages 705-706.

[0036] Furthermore, the optically based digital-to-analog converter 1 shown in this invention can also circumvent the limiting influence of the detector by interleaving techniques similar to those of classical DACs or optically assisted DACs.

[0037] In one embodiment of the invention (see in particular Fig. ), the optically based digital-to-analog converter 1 further comprises a first splitter SP1, which splits a pulsed input signal during operation and makes it available to the first pulse shaper PS1 and the second pulse shaper PS2.

[0038] According to one embodiment of the invention, the optically based digital-to-analog converter 1 further comprises a first splitter SP1, which splits a pulsed input signal during operation and makes it available to the first pulse shaper PS1 and the second pulse shaper PS2, wherein the pulsed optical input signal previously passes through an optical parametric oscillator OPO (see in particular Fig. ).

[0039] In a further embodiment of the invention, the input signal for the first pulse shaper PS1 and the second pulse shaper PS2 is provided by a continuous wave laser CW and a pulser P during operation (see in particular Fig. ).

[0040] According to a further embodiment of the invention, the further signal is generated by a further laser L, wherein the further signal is split during operation by a second splitter SP2 before being fed to the first combiner C1 and the second combiner C2 (see in particular Fig. 1-3).

[0041] In yet another embodiment of the invention, the input signal to the first pulse shaper PS1 and the second pulse shaper PS2 and the further signal originate from a common source (see Fig. ), wherein the input signal to the first pulse shaper PS1 and the second pulse shaper PS2 is changed in frequency by a non-linear element NL during operation.

[0042] According to yet another embodiment of the invention, the first quantum pulse shaper QPS1 comprises a first nonlinear waveguide PPLN-WG1 and a first optical bandpass filter BP1, and the second quantum pulse shaper QPS2 comprises a second nonlinear waveguide PPLN-WG2 and a second optical bandpass filter BP2.

[0043] According to one embodiment, the first quantum pulse shaper QPS1 and / or the second quantum pulse shaper QPS2 (each) comprises a poled nonlinear waveguide.

[0044] According to a further embodiment, the first quantum pulse shaper QPS1 and the second quantum pulse shaper QPS2 each comprise a poled lithium niobate waveguide or a poled potassium titanyl phosphate waveguide.

[0045] In embodiments of the invention, the nonlinear waveguide may be periodically or aperiodically poled.

[0046] According to another embodiment, the optically based digital-to-analog converter 1 is fully integrated, or partially integrated, or implemented with discrete components.

[0047] A further embodiment of the invention may use either two optical sources instead of the first optical source and / or two optical sources instead of the second optical source.

[0048] Another embodiment is in Fig. shown. In this embodiment, the first optical source, which was previously implemented as a pulsed source, is replaced by a continuous source with a downstream pulse-generating element. It should be noted that the pulse-generating element can also take over pulse shaping.

Claims

[1] Optically based digital-to-analog converter (1) comprising • a first pulse shaper (PS1) and a second pulse shaper (PS2), • a first combiner (C1) with a first input (I1) for a signal from the first pulse shaper (PS1) and a second input (I2) for a further signal, • a second combiner (C2) with a first input (I3) for a signal from the second pulse shaper (PS2) and a second input (I4) for the further signal, • a first quantum pulse shaper (QPS1) and a second quantum pulse shaper (QPS2), • wherein the first quantum pulse shaper (QPS1) receives the output signal of the first combiner (C1) during operation and the second quantum pulse shaper (QPS2) receives the output signal of the second combiner (C2) during operation, • a third combiner (C3) which, during operation, combines the output signals of the first quantum pulse shaper (QPS1) and the second quantum pulse shaper (QPS2), • an evaluation unit (AE) which evaluates the output signal of the third combiner (C3). [2] Optically based digital-to-analog converter (1) according to claim 1, characterized by that the optically based digital-to-analog converter (1) further comprises a first splitter (SP1) which splits a pulsed input signal during operation and makes it available to the first pulse shaper (PS1) and the second pulse shaper (PS2). [3] Optically based digital-to-analog converter (1) according to claim 1, characterized by that the optically based digital-to-analog converter (1) further comprises a first splitter (SP1) which splits a pulsed input signal during operation and makes it available to the first pulse shaper (PS1) and the second pulse shaper (PS2), wherein the pulsed optical input signal previously passes through an optical parametric oscillator (OPO). [4] Optically based digital-to-analog converter (1) according to one of the preceding claims, characterized bythat the input signal for the first pulse shaper (PS1) and the second pulse shaper (PS2) is provided by a continuous wave laser (CW) and a pulser (P) in operation. [5] Optically based digital-to-analog converter (1) according to one of the preceding claims, characterized by that the further signal is generated by a further laser (L), wherein the further signal is split during operation by a second splitter (SP2) before being fed to the first combiner (C1) and the second combiner (C2). [6] Optically based digital-to-analog converter (1) according to one of the preceding claims 1 to 4, characterized by that the input signal to the first pulse shaper (PS1) and the second pulse shaper (PS2) and the further signal originate from a common source, wherein the input signal to the first pulse shaper (PS1) and the second pulse shaper (PS2) is changed in frequency during operation by a non-linear element (NL). [7] Optically based digital-to-analog converter (1) according to one of the preceding claims, characterized by that the first quantum pulse shaper (QPS1) has a first nonlinear waveguide (PPLN-WG1) and a first optical bandpass filter (BP1) and that the second quantum pulse shaper (QPS2) has a second nonlinear waveguide (PPLN-WG2) and a second optical bandpass filter (BP2). [8] Optically based digital-to-analog converter (1) according to claim 7, characterized by that both the first quantum pulse shaper (QPS1) and the second quantum pulse shaper (QPS2) each have a poled nonlinear waveguide. [9] Optically based digital-to-analog converter (1) according to one of the preceding claims 7 or 8, characterized by that the first quantum pulse shaper (QPS1) and the second quantum pulse shaper (QPS2) each comprise a poled lithium niobate waveguide or a poled potassium titanyl phosphate waveguide. [10] Optically based digital-to-analog converter (1) according to one of the preceding claims 7 to 9, characterized by that the nonlinear waveguide is periodically poled. [11] Optically based digital-to-analog converter (1) according to one of the preceding claims 7 to 9, characterized by that the nonlinear waveguide is aperiodically poled. [12] Optically based digital-to-analog converter (1) according to one of the preceding claims, characterized by that the optical-based digital-to-analog converter is fully integrated.

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