GB2452960A - Optical device and method for generating an electrical signal with a wideband arbitrary waveform - Google Patents

Optical device and method for generating an electrical signal with a wideband arbitrary waveform Download PDF

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Publication number
GB2452960A
GB2452960A GB0718385A GB0718385A GB2452960A GB 2452960 A GB2452960 A GB 2452960A GB 0718385 A GB0718385 A GB 0718385A GB 0718385 A GB0718385 A GB 0718385A GB 2452960 A GB2452960 A GB 2452960A
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GB
United Kingdom
Prior art keywords
optical
pulses
pulse
output
optical combiner
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB0718385A
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GB0718385D0 (en
GB2452960B (en
Inventor
John Heaton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RFMD UK Ltd
Filtronic PLC
Original Assignee
Filtronic PLC
Filtronic Compound Semiconductors Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Priority to GB0718385.8A priority Critical patent/GB2452960B/en
Publication of GB0718385D0 publication Critical patent/GB0718385D0/en
Priority to PCT/GB2008/002216 priority patent/WO2009037418A1/en
Publication of GB2452960A publication Critical patent/GB2452960A/en
Application granted granted Critical
Publication of GB2452960B publication Critical patent/GB2452960B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03828—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
    • H03K3/42—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B14/00—Transmission systems not characterised by the medium used for transmission
    • H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
    • G02B26/04—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light by periodically varying the intensity of light, e.g. using choppers

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Power Engineering (AREA)
  • Lasers (AREA)
  • Optical Communication System (AREA)

Abstract

A device 1 for generating an electrical signal with a wideband arbitrary waveform uses a plurality of continuous wave lasers 2, each producing light at a different wavelength. A plurality of optical modulators 4 receives an optical signal from one of the lasers 2 and modulates the optical signal in response to an electromagnetic signal. An optical combiner 6, ideally an arrayed waveguide grating, combines the optical signals received at its input ports into one output signal. Each input port of the optical combiner 6 is arranged to receive the output of an associated optical modulator 4 by an optical signal path 9, whereby each optical signal path 9 comprises an optical chopper 10, such as a pulse generator, for chopping the optical signal received from the modulator 4 into optical pulses. A photodetector 11 then receives the output of the optical combiner 11 and produces an electrical signal in response.

Description

A Device and Method for Generating an Electrical Signal with a Wideband Arbitrary Waveform The present invention relates to a device and method for generating an electrical signal with a wideband arbitrary waveform. More particularly, but not exclusively, the present invention relates to a method comprising the steps of modulating the output of a plurality of continuous wave lasers, chopping the modulated outputs into pulses, combining the pulses and providing them to a photodetector. More particularly, but not exclusively, the present invention also relates to a device for performing the method steps.
Devices for generating arbitrary wideband electrical waveforms are known. Such devices however involve time division multiplexing and are difficult and expensive to manufacture.
The present invention seeks to overcome these problems.
In a first aspect the present invention provides a device for generating an electrical signal with a wideband arbitrary waveform comprising a plurality of continuous wave lasers each being adapted to produce light at a different wavelength; a plurality of optical modulators, each optical modulator adapted to receive an optical signal from a continuous wave laser and modulate the optical signal in * 25 response to an electromagnetic signal; * .** *** an optical combiner comprising a plurality of input ports and an output port, the **** . . . . . s,.. optical combiner being adapted to combine the optical signals received at the * input ports at the output port; S * * ** * S**I* each input port of the optical combiner being arranged to receive the output of an associated optical modulator by an optical signal path; each optical signal path comprising an optical chopper for chopping the optical signal received from the modulator into optical pulses; the device further comprising a photodetector for receiving the output of the optical combiner and producing an electrical signal in response thereto.
The device according to the invention can be manufactured from relatively simple components. It is straightforward to manufacture and is lightweight. This makes is particularly suitable for use in avionic applications including radar jamming and false target generation systems.
Preferably, the device further comprises at least one control circuit adapted to control the relative timing of the optical choppers for the generation of optical pulses.
The control circuit can be adapted such that at least some of the pulses are emitted simultaneously by the optical combiner.
The control circuit can be adapted such that at least some of the pulses emitted by the optical combiner overlap in time.
The control circuit can be adapted such that at least one of the pulses emitted by the * 25 optical combiner does not overlap in time with any other pulse.
. ***. *.
Preferably, the control circuit is adapted such that the optical combiner produces a **** plurality of non-overlapping pulses, the pulses forming a series of consecutive pulses.
*.s.**
S
The control circuit can be adapted such that each pulse in the series of non-overlapping 0 * * pulses is spaced apart in time from the next pulse in the series.
0.***S
S
Alternatively, the control circuit is adapted such that the non-overlapping pulses form a contiguous series of pulses.
Preferably, the device further comprises a sampling pulse modulator between the output of the optical combiner and the photodetector for reducing pulse length.
The device can further comprise a pulse compression means for compressing the pulses from the optical combiner in time before being received by the photodetector.
Preferably, the pulse compression means receives the pulses output from the sampling pulse modulator.
Preferably, the device further comprises a low pass filter adapted to smooth the output of the photodetector.
At least one optical signal path of the device can comprise an optical delay element to delay optical signals in the path.
In a further aspect of the invention there is provided a method of generating an electrical signal with a widebarid arbitrary waveform comprising the steps of providing a plurality of continuous wave lasers each emitting light at a different wavelength; passing the light from each of the lasers through a different modulator where it is S. modulated by an electromagnetic signal; *I* S * 55* chopping the modulated light into optical pulses; * * *S ** S
S
S..... S *
providing the pulses to an optical combiner which combines the pulses into a single output; and, providing the combined pulses to a photodetector which produces an electrical signal in response thereto.
At least some of the pulses can be emitted simultaneously by the optical combiner.
At least some of the pulses emitted by the optical combiner can overlap in time.
Preferably, at least one of the pulses emitted by the optical combiner does not overlap in time with any other pulse Preferably, the optical combiner produces a plurality of non-overlapping pulses, the pulses forming a series of consecutive pulses.
Each pulse in the series of non-overlapping pulses can be spaced apart in time from the next pulse in the series.
Alternatively, the non-overlapping pulses can form a contiguous series of pulses.
The method can further comprise the step of passing the combined pulses through a sampling pulse modulator to reduce the pulse length before passing the pulses to the * 25 photodetector. *.* S** *
The method can further comprise the step of passing the pulses from the sampling pulse *** modulator to a pulse compression means for compressing the pulses before passing the *:* pulses to the photodetector. * .s* * * * ** * * *
The method can further comprise the step of passing the output of the photodetector through a low pass filter.
The present invention will now be described by way of example only and not in any limitative sense with reference to the accompanying drawings in which Figure 1 shows, in schematic form, a first embodiment of the invention; Figure 2 shows, in schematic form, a second embodiment of the invention; Figure 3 shows, in schematic form, a third embodiment of the invention; Figure 4 shows, I schematic form, a fourth embodiment of the invention; and, Figure 5 shows, in schematic form, a fifth embodiment of the invention.
Shown in figure 1 is a device I for generating an electrical signal with a wideband arbitrary waveform according to the invention. The device I comprises a plurality of continuous wave lasers 2, each laser 2 being adapted to generate light at a different wavelength.
Connected to the output of each laser 2 is an optical modulator 3. Each optical modulator 3 comprises an input port 4 for receiving the light from its associated laser 2, an output port 5 and at least one optical path (not shown) therebetween. As light passes between input and output ports 4,5 it is modulated by a received electromagnetic signal. The operation of such modulators 3 is known and will not be described in detail. **SS
*.,. The output from the modulators 3 is passed to an optical combiner 6 which in this embodiment is an arrayed waveguide grating. The optical combiner 6 comprises a plurality of input ports 7 and an output port 8. Optical signals received at the input ports 7 * * S are combined at the output port 8. * *
The output port 5 of each optical modulator 3 is connected to the associated input port 7 of the optical combiner 6 by an optical signal path 9. Arranged in each optical signal path 9 is an optical chopper 10. The chopper 10 can be switched between a transmit state and a block state. In the transmit state optical signals received by an optical chopper 10 from an associated modulator 3 on an optical signal path 9 pass through the optical chopper 10 to an input port 7 of the optical combiner 6. In the block state the optical signals do not pass through the optical chopper 10.
The output of the optical combiner 6 is connected to a photodetector 11. Optical pulses received by the optical combiner 6 are received by the photodetector 11 where they are converted into an electrical output signal.
In use the continuous wave lasers 2 each generate a continuous wave optical output, each of a different wavelength. Each optical output is received by an associated optical modulator 3 where it is modulated by an electromagnetic signal. Each optical modulator 3 receives a different modulating electromagnetic signal.
The modulated optical signals are then each passed to a different optical chopper 10. The optical choppers 10 are rapidly turned on and off by a control circuit (not shown) to convert the modulated optical signals into pulses as shown. The pulses are then combined into a single output by the optical combiner 6 before being passed to the photodetector 11.
The electromagnetic modulation signal provided to an optical modulator 3 need only
S
have the correct amplitude at the times when the associated optical chopper 10 is in the eS transmit state. These times can be relatively far apart and hence the modulation signal can *.I.
*,.. be of a relatively low frequency. The output from the optical combiner 6 is made up of s.. pulses from all the different optical modulators 10 and hence can be of a relatively high frequency compared to the individual electromagnetic modulation signals. * * * * *
S
S....' S * In this embodiment the optical choppers 10 are arranged such that the output from the optical combiner 6 is a series of singly produced contiguous pulses. The pulses from different optical signal paths 9 are interdigitated to produce the output from the optical combiner 6. Other timings of the optical choppers 10 are possible. For example the timing between the pulses can be increased such that there is a separation between at least some of the pulses output from the optical combiner 6. Alternatively, the timings between the pulses can be decreased such that at least some of the pulses output from the optical combiner 6 overlap.
In alternative embodiments the timings of the optical choppers 10 can be arranged such that some of the pulses from different optical choppers 10 are emitted simultaneously from the optical combiner 6.
Shown in figure 2 is an alternative embodiment of a device I according to the invention.
In this embodiment the output pulses from the optical combiner 6 are passed through a sampling pulse modulator 12 before they are received by the photodetector 11. If the optical choppers 10 are open for a long period of time the amplitude of the pulses output from the optical choppers 10 varies with the modulating signal as shown. The sampling pulse modulator 12 chops the pulses received from the optical combiner 6 into shorter pulses which give a more instantaneous value of the electromagnetic modulation signal applied to the appropriate optical modulator 10 at a particular point in time.
Shown in figure 3 is a further embodiment of a device I according to the invention. In this embodiment the output from the photodetector Ills passed through a low pass filter 13 to smooth the output pulses into a continuous wave. *I. .* *.
Shown in figure 4 is a further embodiment of a device I according to the invention. In a..
this embodiment the pulses from the optical combiner 6 are passed thorough a pulse compression means 14, compressing the pulses closer together in time. In this embodiment the pulse compression means 14 is a fibre grating. By employing a pulse * S S
I
I
I
compression means 14 the desired output signal shape can be assembled at a relatively low frequency and then increased in frequency by the pulse compression means 14.
Shown in figure 5 is a further embodiment of a device 1 according to the invention. In the embodiments shown in figures 1 to 4 the length of the optical path 9 between the output of the optical chopper 10 and the input of the optical combiner 6 is the same for each optical chopper 10. In the embodiment of figure 5 optical delay elements 14 are included between the optical choppers 10 and the optical combiner 6. The optical choppers 10 can therefore chop the received optical signals simultaneously into pulses but the pulses are still emitted singly from the optical combiner 6. This simplifies the control circuit for the optical choppers 10. It also enables a greater degree of control over spacing between the pulses as it is now determined by the optical delay elements 14, rather than the relative chopping times of the optical choppers.
Typically the electromagnetic modulation signals provided to the optical modulators are microwave signals. The electromagnetic modulation signal can be either an analogue or digital signal. * *S *.s* *SSU.
***,** * S * * *
S **S** *

Claims (25)

  1. I. A device for generating an electrical signal with a wideband arbitrary waveform comprising a plurality of continuous wave lasers each being adapted to produce light at a different wavelength; a plurality of optical modulators, each optical modulator adapted to receive an optical signal from a continuous wave laser and modulate the optical signal in response to an electromagnetic signal; an optical combiner comprising a plurality of input ports and an output port, the optical combiner being adapted to combine the optical signals received at the input ports at the output port; each input port of the optical combiner being arranged to receive the output of an associated optical modulator by an optical signal path; each optical signal path comprising an optical chopper for chopping the optical signal received from the modulator into optical pulses; the device further comprising a photodetector for receiving the output of the optical combiner and producing an electrical signal in response thereto.
  2. 2. A device as claimed in claim I, further comprising at least one control circuit adapted to control the relative timing of the optical choppers for the generation of : optical pulses. *... * . * **.
    *.., 30
  3. 3. A device as claimed in claim 2, wherein the control circuit is adapted such that at least some of the pulses are emitted simultaneously by the optical combiner. S. * * * :
    ****.. S *
  4. 4. A device as claimed in either of claims 2 or 3, wherein the control circuit is adapted such that at least some of the pulses emitted by the optical combiner overlap in time.
  5. 5. A device as claimed in any one of claims 2 to 4, wherein the control circuit is adapted such that at least one of the pulses emitted by the optical combiner does not overlap in time with any other pulse.
  6. 6. A device as claimed in claim 5, wherein the control circuit is adapted such that the optical combiner produces a plurality of non-overlapping pulses, the pulses forming a series of consecutive pulses.
  7. 7. A device as claimed in claim 6, wherein the control circuit is adapted such that each pulse in the series of non-overlapping pulses is spaced apart in time from the next pulse in the series.
  8. 8. A device as claimed in claim 6, wherein the control circuit is adapted such that the non-overlapping pulses form a contiguous series of pulses.
  9. 9. A device as claimed in any one of claims 1 to 8, further comprising a sampling pulse modulator between the output of the optical combiner and the photodetector for reducing pulse length.
  10. 10. A device as claimed in any one of claims I to 9 further comprising a pulse compression means for compressing the pulses from the optical combiner in time before being received by the photodetector.
  11. 11. A device as claimed in claim 10 when dependent on claim 9, wherein the pulse *. 30 compression means receives the pulses output from the sampling pulse modulator. S... * S *..S
    S... 10
    S
  12. 12. A device as claimed in any one of claims 1 to 11, further comprising a low pass filter adapted to smooth the output of the photodetector.
  13. 13. A device as claimed in any one of claims I to 12, wherein at least one optical signal path comprises an optical delay element to delay optical signals in the path.
  14. 14. A method of generating an electrical signal with a wideband arbitrary waveform comprising the steps of providing a plurality of continuous wave lasers each emitting light at a different wavelength; passing the light from each of the lasers through a different modulator where it is modulated by an electromagnetic signal; chopping the modulated light into optical pulses; providing the pulses to an optical combiner which combines the pulses into a single output; and, providing the combined pulses to a photodetector which produces an electrical signal in response thereto.
  15. 15. A method as claimed in claim I 4,wherein at least some of the pulses are emitted simultaneously by the optical combiner.
  16. 16. A method as claimed in either of claims 14 or 15, wherein at least some of the pulses emitted by the optical combiner overlap in time. S... S... * S S...
    S * * S...
    II
    **..S.
    S S
  17. 17. A method as claimed in any one of claims 14 to 16, wherein at least one of the pulses emitted by the optical combiner does not overlap in time with any other pulse
  18. 18. A method as claimed in claim 17, wherein the optical combiner produces a plurality of non-overlapping pulses, the pulses forming a series of consecutive pulses.
  19. 19. A method as claimed in claim 18, wherein each pulse in the series of non-overlapping pulses is spaced apart in time from the next pulse in the series.
  20. 20. A method as claimed in claim 18, wherein the non-overlapping pulses form a contiguous series of pulses.
  21. 21. A method as claimed in any one of claims 14 to 20, further comprising the step of passing the combined pulses through a sampling pulse modulator to reduce the pulse length before passing the pulses to the photodetector.
  22. 22. A method as claimed in claim 21 further comprising the step of passing the pulses from the sampling pulse modulator to a pulse compression means for compressing the pulses before passing the pulses to the photodetector.
  23. 23. A method as claimed in any one of claims 14 to 22, further comprising the step of passing the output of the photodetector through a low pass filter.
  24. 24. A device substantially as hereinbefore described.
    :.:
  25. 25. A method substantially as hereinbefore described. S.. S.'. * S *..S
    S
    S..... * S *.S. * S S : 12
    S.....
GB0718385.8A 2007-09-21 2007-09-21 A device and method for generating an electrical signal with a wideband arbitrary waveform Expired - Fee Related GB2452960B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0718385.8A GB2452960B (en) 2007-09-21 2007-09-21 A device and method for generating an electrical signal with a wideband arbitrary waveform
PCT/GB2008/002216 WO2009037418A1 (en) 2007-09-21 2008-06-26 A device and method for generating an electrical signal with a wideband arbitrary waveform

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0718385.8A GB2452960B (en) 2007-09-21 2007-09-21 A device and method for generating an electrical signal with a wideband arbitrary waveform

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GB0718385D0 GB0718385D0 (en) 2007-10-31
GB2452960A true GB2452960A (en) 2009-03-25
GB2452960B GB2452960B (en) 2013-03-27

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Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3196695B1 (en) * 2016-01-19 2019-12-04 Technische Universität Dresden Optically-assisted time-interleaving digital-to-analogue converter and a method using it

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002054204A2 (en) * 2001-01-08 2002-07-11 Esl Defence Limited Apparatus for generating electrical signals with ultra-wide band arbitrary waveforms
WO2006054090A1 (en) * 2004-11-19 2006-05-26 Filtronic Plc A method or device for generating an electrical signal with a wide band arbitrary waveform
GB2432946A (en) * 2005-12-01 2007-06-06 Filtronic Plc Generating an arbitrary waveform wide band electrical signal.

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2001272903A1 (en) * 2000-04-14 2001-10-30 The Regents Of The University Of California Method and apparatus for arbitrary waveform generation using photonics
US7020396B2 (en) * 2002-04-24 2006-03-28 Hrl Laboratories, Llc Opto-electronic ultra-wideband signal waveform generator and radiator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002054204A2 (en) * 2001-01-08 2002-07-11 Esl Defence Limited Apparatus for generating electrical signals with ultra-wide band arbitrary waveforms
WO2006054090A1 (en) * 2004-11-19 2006-05-26 Filtronic Plc A method or device for generating an electrical signal with a wide band arbitrary waveform
GB2432946A (en) * 2005-12-01 2007-06-06 Filtronic Plc Generating an arbitrary waveform wide band electrical signal.

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GB0718385D0 (en) 2007-10-31
WO2009037418A1 (en) 2009-03-26
GB2452960B (en) 2013-03-27

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