Frequency comb generating device and method for generating frequency comb

Abstract

A frequency comb generating device (10) is described. The frequency comb generating device (10) comprises a pulsed optical light source (12), a sequence generator (16), a light receiving unit (14) and a switch unit (18). The sequence generator (16) is configured to generate a repetitive sequence signal and forward the repetitive sequence signal to at least the switch unit (18). The pulsed optical light source (12) is configured to generate an electromagnetic wave packet and is synchronized with the sequence generator (16). The light receiving unit (14) is configured to receive the electromagnetic wave packet and convert the electromagnetic wave packet into an electrical signal. Based on the repetitive sequence signal, the switch unit (18) is configured to control the pulsed optical light source (12), control the light receiving unit (14), attenuate the electromagnetic wave packet, phase shift the electromagnetic wave packet, attenuate the electrical signal and phase shift the electrical signal. In addition, a method for generating an optical frequency comb and a method for generating an electrical frequency comb are described.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to frequency comb generating devices, methods for generating optical frequency combs, and methods for generating electrical frequency combs. Background Art

[0002] An optical frequency comb or electrical frequency comb consists of a series of substantially equidistant electrical pulses that are approximately shaped as a Dirac delta function. These electrical frequency combs are often used for phase and amplitude calibration of spectrum analyzers or oscilloscopes, where the comb serves as a known reference for the calibration process.

[0003] In order to generate a reference frequency comb, there are two seemingly contradictory requirements. On the one hand, a certain minimum signal-to-noise ratio is required, which is associated with a minimum power level of the electrical frequency comb. The power level of the electrical frequency comb is in turn determined by the number of pulses per time interval, i.e. the pulse frequency in the time domain. Therefore, a high power level requires a high pulse frequency in the time domain.

[0004] On the other hand, a very fine frequency comb is usually required, i.e. the frequency spacing between the peaks in the frequency domain should be very small. However, this corresponds to a large time spacing between the peaks in the time domain, since the spacing in the time and frequency domains are inversely proportional to each other. Therefore, a fine frequency comb in the frequency domain requires a low pulse frequency in the time domain.

[0005] Therefore, there is a need for a frequency comb generating apparatus and a method for generating an optical frequency comb or an electrical frequency comb, which are capable of generating a fine frequency comb with a high signal-to-noise ratio. Summary of the invention

[0006] An embodiment of the present disclosure provides a frequency comb generating device. The frequency comb generating device includes a pulsed optical light source, a sequence generator, a light receiving unit and a switch unit. The sequence generator is configured to generate a repetitive sequence signal and forward the repetitive sequence signal to at least the switch unit. The pulsed optical light source is configured to generate an electromagnetic wave packet. The pulsed optical light source is synchronized with the sequence generator. The light receiving unit is configured to receive the electromagnetic wave packet and convert the electromagnetic wave packet into an electrical signal. The switch unit is configured to control the pulsed optical light source, control the light receiving unit, attenuate the electromagnetic wave packet, phase shift the electromagnetic wave packet, attenuate the electrical signal, and phase shift the electrical signal based on the repetitive sequence signal.

[0007] By combining a pulsed optical light source with a light receiving unit, high power levels can be achieved because independent electromagnetic wave packets can be generated at high frequencies. The switching unit changes the properties of the electrical frequency comb generated by the frequency comb generating device, in particular the pulsed optical light source, so that the spacing between independent Dirac functions in the frequency domain is reduced while still maintaining a high signal-to-noise ratio. Thus, a fine electrical frequency comb with a high signal-to-noise ratio is achieved.

[0008] In practice, the electromagnetic wave packets received by the light receiving unit correspond to optical radiation or more precisely electromagnetic waves in the optical wavelength range, for example between 100 nm and 1 mm.

[0009] Therein and hereinafter, the term "light" is to be understood as not being restricted to the visible range, but also including the infrared and ultraviolet frequency ranges.

[0010] Furthermore, the term "synchronous" means that the frequency of the generation of electromagnetic wave packets by the pulsed optical light source (i.e., the number of wave packets per time interval, not the optical frequency itself) and the number of information fragments generated per time interval (contained in the repeating sequence signal) have a predetermined ratio, such as one. Alternatively or additionally, there is a predetermined phase relationship between the generation of wave packets and the generation of information fragments.

[0011] A phase shift of the electromagnetic wave packet and / or of the electrical signal corresponds to delaying at least one specific signal portion in time. This becomes apparent because a pulsed optical light source can generate electromagnetic pulses, where the pulses can only be controlled in terms of amplitude and delay (phase).

[0012] The switching units may be assigned to different components of the frequency comb generating device such that the switching units can interact directly with the optical light source.Alternatively or additionally, the switching units are connected to the light receiving units in order to control the light receiving units.

[0013] Alternatively or additionally, the switching unit is assigned to the optical components of the frequency comb generating device when the switching unit attenuates and / or phase-shifts the electromagnetic wave packets.

[0014] Alternatively or additionally, the switching unit is assigned to the electrical components of the frequency comb generating device when the switching unit attenuates and / or phase-shifts the electrical signal.

[0015] Typically, the switch unit interacts with the corresponding component based on a repetitive sequence signal generated by a sequencer.

[0016] In other words, based on the repetitive sequence signal, the switch unit is configured to control the pulsed optical light source to control the light receiving unit, attenuate the electromagnetic wave packet, phase shift the electromagnetic wave packet, attenuate the electrical signal and / or phase shift the electrical signal. For this purpose, the switch unit is connected to the pulsed optical light source, the light receiving unit, the optical components of the frequency comb generating device and / or the electrical components of the frequency comb generating device.

[0017] In one embodiment according to the present disclosure, the sequence generator is configured to generate a pseudo-random binary sequence. The binary sequence may correspond to a digital signal. Therefore, the independent information fragments contained in the repeating sequence signal are "0" and "1", or at least may be mapped to these two values, wherein the order of the independent information fragments is pseudo-randomly generated. After a predefined time interval, the same order may be repeated.

[0018] The light receiving unit may be a photodiode. Thus, the electromagnetic wave packet is converted into at least one electrical signal in a specific energy-efficient manner and in real time.

[0019] In another embodiment according to the invention, the pulsed optical light source is an optical pulsed laser. An optical pulsed laser is capable of generating high intensity electromagnetic wave packets of particularly short duration, thereby best approximating a Dirac comb.

[0020] For example, the sequencer, the light receiving unit and the switch unit are placed on the same chip or die. A compact frequency comb generating device is provided, because the corresponding components, namely the sequencer, the light receiving unit and the switch unit, are located on a common chip or more precisely on a common die. The optional control unit can also be located on a common chip or more precisely on a common die.

[0021] According to another aspect, the pulsed optical light source and the light receiving unit are optically connected to each other via an optical fiber. Due to the optical fiber, the pulsed optical light source and the light receiving unit do not need to be perfectly aligned. Therefore, intensity losses due to misalignment and / or other disturbances are reduced or even eliminated, which in turn simplifies the manufacture of the frequency comb generation device.

[0022] In one embodiment of the present invention, the switch unit is configured to control the pulsed optical light source to generate an electromagnetic wave packet for at least one specific current value of the repetitive sequence signal, and not to generate an electromagnetic wave packet for at least one other specific current value of the repetitive sequence signal. The current value corresponds to the corresponding actual value of the repetitive sequence signal. Compared with the all-optical frequency comb, the generated optical frequency comb in the time domain lacks some teeth, which translates into a shorter distance between independent Dirac functions in the frequency domain. Therefore, by canceling out some Dirac functions in the time domain (or more precisely not generating them in the first place), a fine optical frequency comb is achieved, which is then converted into a fine electrical frequency comb by the optical receiving unit.

[0023] The switch unit can be configured to control the pulsed optical light source to generate an electromagnetic wave packet for each bit of a binary sequence having one of two possible values, and not generate an electromagnetic wave packet for each bit of the binary sequence having the other of the two possible values. For example, the switch unit can control the pulsed optical light source to generate an optical pulse for each "1" in the binary sequence, and not generate an optical pulse for each "0" in the binary sequence, and vice versa.

[0024] According to another aspect, the switch unit is an electrical switch connected to the light receiving unit, the switch unit being positioned downstream of the light receiving unit. Thus, the switch unit is assigned to the electrical component of the frequency comb generating device. The switch unit is configured to attenuate and / or phase shift the electrical signal generated by the light receiving unit based on the current value of the repetitive sequence signal. For example, the switch unit is configured to cancel the electrical pulses for at least one value and not change the electrical pulses for other values. By canceling some electrical pulses, a fine electrical frequency comb is generated, as explained above. In particular, the switch unit can be a high bandwidth electrical switch.

[0025] In one embodiment of the present disclosure, the switch unit is an optical switch connected to the light receiving unit, and the switch unit is located upstream of the light receiving unit. Therefore, the switch unit is assigned to the optical component of the frequency comb generating device. The switch unit is configured to attenuate and / or phase shift the electromagnetic wave packet generated by the pulsed optical light source based on the current value of the repetitive sequence signal. For example, the switch unit is configured to cancel the electromagnetic wave packet for at least one value and not change the electromagnetic wave packet for other values. By canceling some electromagnetic wave packets, a fine optical frequency comb is generated, as explained above. In particular, the switch unit can be a high-bandwidth optical switch.

[0026] In another embodiment according to the present disclosure, the switch unit is configured to control the optical receiving unit to convert the received electromagnetic wave packet into an electrical signal with a predefined property, wherein the predefined property depends on the current value of the repeating sequence signal. Thus, the generated electrical frequency comb is changed so that the interval between independent Dirac functions in the frequency domain is reduced while still maintaining a high signal-to-noise ratio.

[0027] The repeating sequence signal may comprise a ternary sequence. Thus, the independent information pieces are "-1", "0" and "1", or at least the actual values ​​may be mapped onto these three values.

[0028] According to one aspect, the switch unit is configured to control the light receiving unit to generate a positive voltage pulse, a negative voltage pulse, or a no voltage pulse based on the current value of the ternary sequence. The light receiving unit can generate a positive voltage electrical pulse for each "1" in the ternary sequence, a negative voltage electrical pulse for each "-1" in the ternary sequence, and can not generate an electrical pulse for each "0" in the ternary sequence. Of course, any other mapping of the current value of the repeating sequence signal to the properties of the electrical pulse is also possible. Again, this results in a fine electrical frequency comb with a high signal-to-noise ratio.

[0029] According to another aspect, the light receiving unit is a switchable photodiode including two conversion elements, wherein the switch unit is configured to selectively activate the conversion elements based on the current value of the ternary sequence. In particular, one conversion element is configured to generate a negative voltage pulse, while the other conversion element is configured to generate a positive voltage pulse.

[0030] In another embodiment, the light receiving unit is a switchable photodiode, which includes two conversion elements and a control unit, wherein the switch unit is configured to forward the repetitive sequence signal to the control unit, and wherein the control unit is configured to selectively activate the two conversion elements based on the repetitive sequence signal. In particular, one conversion element is configured to generate a negative voltage pulse, and the other conversion element is configured to generate a positive voltage pulse.

[0031] An embodiment of the present invention also provides a method for generating an optical frequency comb, comprising the following steps: generating a repetitive sequence signal; and generating an optical electromagnetic wave packet; wherein a portion of the optical electromagnetic wave packet is filtered out based on the repetitive sequence signal, or the step of generating the electromagnetic wave packet is controlled based on the repetitive sequence signal.

[0032] In other words, the optical frequency comb is obtained by directly generating the optical frequency comb by controlling a light source, in particular an optical pulsed light source, or by generating an all-optical frequency comb and cancelling some Dirac functions in the time domain, as explained above. Compared to the all-optical frequency comb, the generated optical frequency comb in the time domain lacks some teeth, which translates into a shorter distance between independent Dirac functions in the frequency domain. Therefore, by cancelling some Dirac functions in the time domain (or more precisely not generating them in the first place), a refined optical frequency comb is achieved. The modified optical frequency comb can then be forwarded to other devices, for example, for the purpose of calibrating the device.

[0033] With regard to further advantages, reference is made to the explanations given above.

[0034] According to one aspect, the repetitive sequence signal comprises a binary or ternary sequence.

[0035] The embodiments of the present disclosure also provide a method for generating an electrical frequency comb, comprising the following steps: generating a repetitive sequence signal; generating an optical electromagnetic wave packet; receiving the optical electromagnetic wave packet; converting the optical electromagnetic wave packet into an electrical signal; wherein, based on the repetitive sequence signal, a portion of the optical electromagnetic wave packet or a portion of the electrical signal is filtered out, or wherein the step of generating the electromagnetic wave packet is controlled based on the repetitive sequence signal, or the step of receiving and converting the optical electromagnetic wave packet is controlled based on the repetitive sequence signal. With regard to the advantages, reference is made to the explanation given above.

[0036] Therefore, the method for generating an electrical frequency comb may include a method for generating an optical frequency comb at least in part because a repetitive sequence signal and an optical electromagnetic wave packet are generated. In addition, a portion of the optical electromagnetic wave packet is filtered out based on the repetitive sequence signal, or the step of generating the electromagnetic wave packet is controlled based on the repetitive sequence signal.

[0037] Thus, the method for generating an electrical frequency comb can be rewritten to perform the method for generating an optical frequency comb as defined above, wherein optical electromagnetic wave packets are received and converted into electrical signals.

[0038] Furthermore, part of the electrical signal is filtered out based on the repetitive sequence signal, or the step of generating the electromagnetic wave packet is controlled based on the repetitive sequence signal, or the step of receiving and converting the optical electromagnetic wave packet is controlled based on the repetitive sequence signal.

[0039] According to one aspect, the repetitive sequence signal comprises a binary or ternary sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The foregoing aspects and many of the attendant advantages of the claimed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings, wherein:

[0041] - Figure 1 Schematically shows a first variation of a frequency comb generating device according to the present disclosure;

[0042] - Figure 2 schematically shows a second variation of the frequency comb generating device according to the present disclosure;

[0043] - Figure 3 schematically shows a third variation of the frequency comb generating device according to the present disclosure;

[0044] - Figure 4 schematically shows a fourth variation of the frequency comb generating device according to the present disclosure;

[0045] - Figure 5 schematically shows a flow chart of a first variant of a method for generating an electrical frequency comb according to the present disclosure;

[0046] - Figure 6 schematically shows a flow chart of a second variant of the method for generating an electrical frequency comb according to the present disclosure;

[0047] - Figure 7 schematically shows a flow chart of a third variant of the method for generating an electrical frequency comb according to the present disclosure; and

[0048] - Figure 8 A flow chart of a fourth variant of the method for generating an electrical frequency comb according to the present disclosure is schematically shown. DETAILED DESCRIPTION

[0049] The detailed description set forth below in conjunction with the accompanying drawings (in which like reference numerals refer to like elements) is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided only as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the claimed subject matter to the precise form disclosed.

[0050] In the following, the term "light" is to be understood as not being limited to the visible range, but also including the infrared and ultraviolet frequency ranges.

[0051] Figures 1 to 4 Schematically shown are different variants of a frequency comb generating device 10. In all variants, the frequency comb generating device 10 comprises a pulsed optical light source 12, a light receiving unit 14, a sequencer 16 and a switching unit 18.

[0052] exist Figures 1 to 4 In the figure, dotted lines represent connections that send signals in any manner. This can include wired or wireless communications between independent device functional units (also called components). Short-dashed lines represent optical connections, that is, light can be transmitted between different devices through air, through a vacuum and / or via one or more optical fibers. Finally, solid lines represent connections based on electrical wires. When an arrow is attached to a connecting line, it should be understood that the arrow depicts the direction of travel of the corresponding optical signal or electrical signal, respectively.

[0053] The sequencer 16 is configured to generate a repetitive sequence signal and to forward the repetitive sequence signal to a switch unit 18 to which the sequencer 16 is signalingly connected.

[0054] The repeating sequence may include a binary and / or ternary sequence which repeats after a predefined time interval with a sequence frequency f S In other words, the sequence generator 16 generates independent information fragments at a frequency f S Information segments are generated, wherein each information segment can have one of two values ​​or one of three values, respectively.

[0055] In particular, the repetitive sequence may be a pseudo-random binary sequence (PRBS).

[0056] The pulsed optical light source 12 is configured to generate electromagnetic wave packets, which will be referred to as optical pulses in the following. The pulsed optical light source 12 generates electromagnetic wave packets at a fundamental pulse frequency f p Generate optical pulses, which means the time between two pulses is usually T p =1 / f p In particular, the optical light source 12 is configured to generate short optical pulses or ultrashort optical pulses, ie, even for high frequencies f p , the width of an independent pulse is also much smaller than the time between two pulses. For example, the optical light source 12 can be an optical pulse laser.

[0057] In the time domain, each optical pulse typically has the form of a sinusoid, with the maximum amplitude limited by a Gaussian function. Since the individual optical pulses are very short, without being limited in generality, each optical pulse will be approximated to have the form of the following Dirac function.

[0058] The pulsed optical light source 12 is synchronized with the sequencer 16, which means that the pulse frequency f p and sequence frequency f s With a predefined ratio n = f p / f s .

[0059] In a particular embodiment, the ratio n is equal to 1, which means that the optical pulses contained in the repetitive sequence signal and the independent information fragments are generated with the same frequency.

[0060] Furthermore, the optical light source 12 and the sequencer 16 may be phase-synchronized, which means that there is a predetermined time delay interval between the generation of an optical pulse and a corresponding information segment contained in the repetitive sequence signal.

[0061] The light receiving unit 14 is configured to receive electromagnetic wave packets, ie, optical pulses, and convert the optical pulses into corresponding electrical signals. For example, the light receiving unit 14 is a photodiode.

[0062] The functionality of the switch unit 18 depends at least in part on the embodiment and will be described below with respect to Figures 1 to 4 Each embodiment of the frequency comb generating device 10 is described in more detail.

[0063] exist Figure 1 In the embodiment shown in , the switch unit 18 is configured to control the pulsed optical light source 12 based on the repetitive sequence signal generated by the sequence generator 16, more specifically based on the current value of the repetitive sequence signal.

[0064] The switch unit 18 may be separate from the sequencer 16 and the pulsed optical light source 12. Alternatively, the switch unit 18 may be integrated into the sequencer 16 or into the pulsed optical light source 12.

[0065] In practice, the pulsed optical light source 12, the sequencer 16 and / or the switch unit 18 may be formed integrally with one another, such that the respective components are accommodated in a common housing.

[0066] In this embodiment, an electrical frequency comb 20 having known characteristics is generated, as described below with reference to Figure 1 and Figure 5 Explained.

[0067] First, a repetitive sequence signal is generated via a sequence generator as described above (step S1 a ).

[0068] The switch unit 18 controls the pulsed optical light source 12 to generate an optical pulse whenever the current information segment contained in the repetitive sequence signal is equal to at least one possible value, and does not generate an optical pulse when the current information segment contained in the repetitive sequence signal is equal to one of the other possible values ​​(step S2). a ).

[0069] For example, if the repeating sequence is a binary sequence, possible independent information fragments are "0" and "1". In this case, the switch unit 18 can control the pulsed optical light source 12 to generate an optical pulse for each "1" in the binary sequence and not generate an optical pulse for each "0" in the binary sequence, and vice versa.

[0070] Without any additional control, the pulsed optical light source 12 will generate a pulse at a frequency f p Generate optical pulses, which will result in an optical frequency comb 22 with a spacing of f of independent Dirac functions in the frequency domain p .

[0071] However, step S2 a The result is that the spacing of the modified optical frequency comb 22' is much smaller than the spacing between independent Dirac functions. p And has a high signal-to-noise ratio.

[0072] Then the modified optical frequency comb 22' is received (step S3 a ) and converts it into the electrical frequency comb 20 via the light receiving unit 14 (step S4 a ).

[0073] Step S4 aThe result (ie, electrical frequency comb 20) is characterized by small spacing between independent Dirac functions in the frequency domain and a high signal-to-noise ratio.

[0074] exist Figure 2 In the embodiment shown in FIG. 1 , the switch unit 18 is an optical switch connected to the pulsed optical light source 12 and the light receiving unit 14. The switch unit 18 is positioned downstream of the pulsed optical light source 12 and upstream of the light receiving unit 14. In other words, the switch unit 18 is positioned between the pulsed optical light source 12 and the light receiving unit 14.

[0075] The switch unit 18 is configured to attenuate and / or phase-shift the optical pulses (also referred to as electromagnetic wave packets) generated by the pulsed optical light source 12 based on the current value of the repetitive sequence signal.

[0076] In this embodiment, an electrical frequency comb 20 having known characteristics is generated, as described below with reference to Figure 2 and Figure 6 Explained.

[0077] First, a repetitive sequence signal is generated via a sequence generator as described above (step S1 b ).

[0078] In addition, an optical light source 12 is used to generate a p Generate optical pulses (step S2 b ), which results in the spacing of the optical frequency comb 22 being the f of the independent Dirac functions in the frequency domain p .

[0079] The switch unit 18 filters the optical frequency comb 22 based on the current value of the repetition frequency signal (step S3 b ).

[0080] More specifically, the switch unit 18 attenuates and / or phase shifts the optical pulse passing through the switch unit 18 whenever the current information segment contained in the repetitive sequence signal is equal to at least one possible value, and does not change the optical pulse when the current information segment contained in the repetitive sequence signal is equal to one of the other possible values.

[0081] For example, if the repeating sequence is a binary sequence, possible independent pieces of information would be "0" and "1". In this case, the switch unit 18 may change the optical pulse for each "1" in the binary sequence and may not change the optical pulse for each "0" in the binary sequence, and vice versa.

[0082] In one specific example, the switch unit 18 completely filters out some optical pulses based on the corresponding values ​​of the repetitive sequence signal.

[0083] Step S3 bThe result is a modified optical frequency comb 22' which is identical to the optical frequency comb described above in the context of the first possible embodiment.

[0084] Therefore, the remaining steps are the same, namely receiving the modified optical frequency comb 22' (step S3 b ) and converts it into the electrical frequency comb 20 via the light receiving unit 14 (step S4).

[0085] exist Figure 3 In the embodiment shown in , the switch unit 18 is an electrical switch connected to the light receiving unit 14, wherein the switch unit 18 is located downstream of the light receiving unit 14. Therefore, the electrical signal generated by the light receiving unit is forwarded to the switch unit 18.

[0086] The switch unit 18 is configured to attenuate and / or phase-shift the electrical pulse generated by the light receiving unit 14 based on a current value of the repetitive sequence signal.

[0087] In this embodiment, an electrical frequency comb 20 having known characteristics is generated, as described below with reference to Figure 3 and Figure 7 Explained.

[0088] First, a repetitive sequence signal is generated via a sequence generator as described above (step S1 c ).

[0089] In addition, an optical light source 12 is used to generate a p Generate optical pulses (step S2 c ), which results in the spacing of the optical frequency comb 22 being the f of the independent Dirac functions in the frequency domain p .

[0090] The optical frequency comb 22 is converted by the light receiving unit 14 into a corresponding intermediate electrical frequency comb 24 (step S3 c ).

[0091] The switch unit 18 filters the intermediate electrical frequency comb 24 based on the current value of the repetition frequency signal (step S4 c ).

[0092] More specifically, the switching unit 18 attenuates and / or phase shifts the electrical pulse passing through the switching unit 18 whenever the current information segment contained in the repetitive sequence signal is equal to at least one possible value, and does not change the electrical pulse when the current information segment contained in the repetitive sequence signal is equal to one of the other possible values.

[0093] For example, if the repeating sequence is a binary sequence, the possible independent pieces of information would be "0" and "1." In this case, the switch unit 18 may change the electrical pulse for each "1" in the binary sequence and may not change the optical pulse for each "0" in the binary sequence, and vice versa.

[0094] In one specific example, the switch unit 18 completely filters out some electrical pulses based on the corresponding values ​​of the repeating sequence signal.

[0095] Step S4 c The result is an electric frequency comb 20 which is identical to the one described in the context of the first embodiment.

[0096] exist Figure 4 In the embodiment shown in , the switch unit 18 is configured to control the light receiving unit 14 based on the repetitive sequence signal, more specifically based on the current value of the repetitive sequence signal.

[0097] The switch unit 18 may be separate from the sequencer 16 and the light receiving unit 14. Alternatively, the switch unit 18 may be integrated into the sequencer 16 or into the light receiving unit 14.

[0098] The light receiving unit 14, the sequencer 16 and the switch unit 18 can be placed on the same chip or the same die, also referred to as a common chip or more precisely a common die. Thus, a compact frequency comb generating device 10 is obtained.

[0099] In this embodiment, an electrical frequency comb 20 having known characteristics is generated, as described below with reference to Figure 4 and Figure 8 Explained.

[0100] First, a repetitive sequence signal is generated via the sequence generator 16 as described above (step S1 d ).

[0101] In addition, an optical light source 12 is used to generate a p Generate optical pulses (step S2 d ), which results in the spacing of the optical frequency comb 22 being the f of the independent Dirac functions in the frequency domain p .

[0102] Then, the optical pulse is received via the light receiving unit 14 (step S3 d ), wherein the light receiving unit 14 is controlled by the switch unit 18 to convert each received optical pulse into a corresponding electrical pulse having predefined properties (step S4 d ), thereby generating an electrical frequency comb 20.

[0103] In step S4 dIn this case, the predefined properties of each electrical pulse depend on the current value of the repetitive sequence signal.

[0104] More precisely, the light receiving unit 14 generates an electrical pulse whenever the current information segment contained in the repetitive sequence signal is equal to at least one possible value, and does not generate an electrical pulse when the current information segment contained in the repetitive sequence signal is equal to one of the other possible values.

[0105] For example, if the repeating sequence is a binary sequence, possible independent information fragments will be "0" and "1". In this case, the light receiving unit 14 may generate an electrical pulse for each "1" in the binary sequence, and may not generate an electrical pulse for each "0" in the binary sequence, and vice versa.

[0106] In another example, if the repeating sequence is a ternary sequence, the independent pieces of information would be "-1", "0", and "1", or at least the actual values ​​could be mapped to these three values.

[0107] In this case, the light receiving unit 14 may generate a positive voltage electrical pulse for each "1" in the ternary sequence, a negative voltage electrical pulse for each "-1" in the ternary sequence, and may not generate an electrical pulse for each "0" in the ternary sequence. Of course, any other mapping of the current value of the repeating sequence signal to the properties of the electrical pulse is also possible.

[0108] In order to generate the positive voltage electrical pulse and the negative voltage electrical pulse, the light receiving unit 14 may include a first conversion element 26 configured to generate the positive voltage electrical pulse and a second conversion element 28 configured to generate the negative voltage electrical pulse.

[0109] The switch unit 18 may be configured to selectively activate one of the two conversion elements 26 , 28 based on the current value of the ternary sequence.

[0110] Alternatively, the light receiving unit 14 may include a control unit 30 configured to selectively activate the conversion elements 26 , 28 based on corresponding control signals received from the switch unit 18 .

[0111] Since the control unit 30 is a part of the light receiving unit 14 , the control unit 30 may also be located on the same chip, or more precisely, on the same die.

[0112] As described above, the switch unit 18 may be assigned to different components of the frequency comb generating device 10 , which includes optical components and electrical components separated by the light receiving unit 14 .

[0113] therefore, Figure 1 and Figure 2The variant shown in FIG. 1 shows that the switching unit 18 is assigned to the optical components of the frequency comb generating device 10, while Figure 3 In the variant shown in FIG. 1 , a switching unit 18 is assigned to the electrical components of the frequency comb generating device 10 .

[0114] according to Figure 4 A variation of shows that the switch unit 18 is assigned to the light receiving unit 14 itself while controlling the light receiving unit 14. Therefore, the conversion property can be controlled via the switch unit 18.

[0115] like Figure 1 and Figure 2 The components of the frequency comb generating device 10 shown in FIG. 1 (in particular the pulsed optical light source 12, the sequencer 16 and the switching unit 18) can also be used to generate only a modified optical frequency comb 22', ie, the conversion of the modified optical frequency comb 22' into the electrical frequency comb 20 can be omitted.

[0116] This can be done by just executing Figure 1 and Figure 5 Explanation of step S1 a and S2 a , or by just executing the above reference Figure 2 and Figure 6 Explanation of step S1 b 、S2 b and S3 b to achieve.

[0117] Compared to the full optical frequency comb, the generated modified optical frequency comb 22' in the time domain lacks some teeth, which translates into shorter distances between independent Dirac functions in the frequency domain. Therefore, by canceling some Dirac functions in the time domain (or more precisely not generating them in the first place), a finely modified optical frequency comb 22' is achieved.

[0118] The modified optical frequency comb 22' may then be forwarded to a further device, for example for the purpose of calibrating said device.

Claims

1. A frequency comb generating device (10), comprising: A pulse optical light source (12), a sequence generator (16), a light receiving unit (14) and a switch unit (18), The sequence generator (16) is configured to generate a repetitive sequence signal and forward the repetitive sequence signal to at least the switch unit (18), wherein the repetitive sequence signal is a pseudo-random binary sequence or a ternary sequence, The pulsed optical light source (12) is configured to generate electromagnetic wave packets, and the pulsed optical light source (12) is synchronized with the sequencer (16), wherein the generated electromagnetic wave packets are optical pulses, wherein the pulsed optical light source (12) is configured to generate optical pulses having a fundamental pulse frequency, The light receiving unit (14) is configured to receive the electromagnetic wave packet, and the light receiving unit (14) is configured to convert the electromagnetic wave packet into an electrical signal, The switch unit (18) is configured to perform at least one of the following based on the repetitive sequence signal: control the pulsed optical light source (12), control the light receiving unit (14), attenuate the electromagnetic wave packet, phase-shift the electromagnetic wave packet, attenuate the electrical signal, and phase-shift the electrical signal. The switch unit (18) is configured to change the properties of the electrical frequency comb generated by the frequency comb generating device (10) so that the intervals between independent Dirac functions in the frequency domain are reduced.

2. The frequency comb generating device (10) according to claim 1, wherein the light receiving unit (14) is a photodiode and / or wherein the pulsed optical light source (12) is an optical pulsed laser.

3. The frequency comb generating device (10) according to claim 1 or 2, wherein: The sequence generator (16), the light receiving unit (14) and the switch unit (18) are placed on the same chip or the same die.

4. The frequency comb generating device (10) according to claim 1 or 2, wherein: The pulse optical light source (12) and the light receiving unit (14) are optically connected to each other via an optical fiber.

5. The frequency comb generating device (10) according to claim 1 or 2, wherein: The switch unit (18) is configured to control the pulsed optical light source (12) to generate an electromagnetic wave packet for at least one specific current value of the repetitive sequence signal and not to generate an electromagnetic wave packet for at least one other specific current value of the repetitive sequence signal.

6. The frequency comb generating device (10) according to claim 5, wherein the switching unit (18) is configured to control the pulsed optical light source (12) to generate an electromagnetic wave packet for each bit of a binary sequence having one of two possible values, and not to generate an electromagnetic wave packet for each bit having the other of the two possible values.

7. The frequency comb generating device (10) according to claim 1 or 2, wherein: The switch unit (18) is an electrical switch connected to the light receiving unit (14), and the switch unit (18) is located downstream of the light receiving unit (14).

8. The frequency comb generating device (10) according to claim 1 or 2, wherein: The switch unit (18) is an optical switch connected to the light receiving unit (14), and the switch unit (18) is positioned upstream of the light receiving unit (14).

9. The frequency comb generating device (10) according to claim 1, wherein: The switch unit (18) is configured to control the optical receiving unit (14) to convert the received electromagnetic wave packet into an electrical signal with a predefined property, wherein the predefined property depends on the current value of the repetitive sequence signal.

10. The frequency comb generating device (10) according to claim 1 or 2, wherein: The switch unit (18) is configured to control the light receiving unit (14) to generate a positive voltage pulse, a negative voltage pulse, or a no voltage pulse based on a current value of the ternary sequence.

11. The frequency comb generating device (10) according to claim 10, wherein the light receiving unit (14) is a switchable photodiode comprising two conversion elements (26, 28), and the switching unit (18) is configured to selectively activate the conversion elements (26, 28) based on the current value of the ternary sequence.

12. The frequency comb generating device (10) according to claim 10, wherein the light receiving unit (14) is a switchable photodiode, which includes two conversion elements (26, 28) and a control unit (30), wherein the switch unit (18) is configured to forward the repetitive sequence signal to the control unit (30), and wherein the control unit (30) is configured to selectively activate the two conversion elements (26, 28) based on the repetitive sequence signal.

13. A method for generating an optical frequency comb (22), comprising the steps of: - generating a repeating sequence signal, wherein the repeating sequence signal is a pseudo-random binary sequence or a ternary sequence; and - generating optical electromagnetic wave packets by a pulsed optical light source (12), wherein the generated electromagnetic wave packets are optical pulses, wherein the pulsed optical light source (12) is configured to generate optical electromagnetic wave packets having a fundamental pulse frequency f p Optical pulses; Part of the optical electromagnetic wave packet is filtered out based on the repetitive sequence signal, or the step of generating the electromagnetic wave packet is controlled based on the repetitive sequence signal, so that the generated optical frequency comb in the time domain lacks some teeth compared to the all-optical frequency comb, which translates into a shorter distance between independent Dirac functions in the frequency domain.

14. A method for generating an electrical frequency comb, comprising the steps of: - generating a repeating sequence signal, wherein the repeating sequence signal is a pseudo-random binary sequence or a ternary sequence; - generating optical electromagnetic wave packets by a pulsed optical light source (12), wherein the generated electromagnetic wave packets are optical pulses, wherein the pulsed optical light source (12) is configured to generate optical electromagnetic wave packets having a fundamental pulse frequency f p Optical pulses; - receiving the optical electromagnetic wave packet; and - converting the optical electromagnetic wave packet into an electrical signal; Wherein, part of the optical electromagnetic wave packet or part of the electrical signal is filtered out based on the repetitive sequence signal, or the step of generating the electromagnetic wave packet is controlled based on the repetitive sequence signal, or the step of receiving and converting the optical electromagnetic wave packet is controlled based on the repetitive sequence signal, so that the properties of the generated electrical frequency comb are changed so that the intervals between independent Dirac functions in the frequency domain are reduced.

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