WO2015071582A1

WO2015071582A1 - Method and device for extracting a low-frequency wave form from an electro-optical component

Info

Publication number: WO2015071582A1
Application number: PCT/FR2014/052864
Authority: WO
Inventors: Kevin Sanchez; Kevin MELENDEZ; Philippe Perdu
Original assignee: Centre National D'Études Spatiales C N E S
Priority date: 2013-11-12
Filing date: 2014-11-07
Publication date: 2015-05-21
Also published as: FR3013122B1; FR3013122A1

Abstract

The invention concerns a method and a device for extracting a wave form from an activity taking place in an electro-optical component (11) in a frequency band Δf0 at least partially lower than the bandwidth Δf1 of the electrical processing used to process optical radiation (23) reflected by said component. The reflected optical radiation is formed from carrier radiation, of periodic intensity over a frequency fopt, modulated by variations induced by said activity. Each electrical detection signal (24) comprises a periodic carrier of frequency f1 corresponding to fopt, modulated by a modulation signal representative of said activity, fopt being chosen such that at least one of frequency bands f1-Δf0 and f1 +ΔfO is contained in Δf1. A demodulation of the electrical detection signal (24) provides a signal representative of the wave form.

Description

METHOD AND DEVICE FOR EXTRACTING A LOW FREQUENCY WAVEFORM OF AN ELECTRO-OPTICAL COMPONENT

The invention relates to a method and a device for extracting a waveform of an activity occurring in an electro-optical component in a frequency band AfO at least partly below the passband Afl of a electrical treatment used to extract said waveform from at least one optical radiation reflected by the electro-optical component.

Throughout the text, the term "electro-optical" refers to the property of a component consisting in producing, under the effect of at least one incident optical radiation, reflected optical radiation of which at least one characteristic (in particular chosen from the amplitude, the wavelength, the polarization and the phase) is modified according to the electrical environment in which the component is placed or which occurs inside this component. The electro-optical component may be an electronic circuit having electro-optical properties, said activity then being an electrical activity occurring within this electronic circuit. The electro-optical component may instead be an electro-optical crystal, for example sensitive to the Pockels effect, having a variable refractive index depending on the electric field to which it is subjected. In addition, throughout the text, the term "continuous periodic" denotes any periodic and continuous function in the mathematical sense of the term in time; in particular, the term "continuous" does not mean that the function is constant in time, as is usually the case in its use in relation to certain electrical variables (voltage, intensity ...).

Various techniques are already known (in particular those sometimes called laser voltage probing (LVP, see for example http://en.wikipedia.org/wiki/Laser_voltage_prober) or electro-optical probing (EOP) by contact of a probe. (see for example EP 0953846) or without contact (see for example http://www.hamamatsu.com/resources/pdf/sys/e_eop.pdf) allowing, by a poll optical and electrical processing, extracting a waveform of an activity occurring in an electro-optical component.

The known techniques of electro-optical sounding have the advantage of making non-invasive but relatively accurate measurements. They can be used in particular for the analysis of complex electronic circuits with high integration (integrated circuits VLSI or assemblies (so-called SiP or "System in Package") of integrated circuits (with active components (microprocessors, memories, ...) and / or passive (resistors, capacitors, inductances, etc.) and / or microsystems (for example MEMS), in particular for the detection of defects in such electronic circuits.

In these electro-optical probing techniques, the characteristic variations of the reflected optical radiation are very small in absolute value (the incident probe beam must not itself disturb the operation of the component nor modify its properties) and in relation to the average value of this characteristic. However, they make it possible to detect very small variations, typically electrical voltages as low as a few tens of millivolts, which makes them particularly applicable to the analysis of analog or mixed circuits.

In general, the activity to be detected is repetitive (for example in the case of the application of test vectors on an electronic circuit) and the measurements are repeated multiple times (typically of the order of several hundreds of thousands of times ) to achieve an integration or an average to overcome the noise. This results in particular that the devices used are relatively complex and expensive, and in particular that the optical radiation sources must be particularly stable and accurate so as not to disturb the measurement and to avoid having to perform too many repetitive measures to overcome the noise. In addition, the electrical treatment of each reflected optical radiation that must be performed to extract the waveform necessarily involves an amplification of the electrical signal. However, such amplification necessarily has a predetermined bandwidth that can not cover the entire frequency spectrum AfO, often unknown, may relate to said activity. In general, the known devices are more particularly adapted to be able to measure in frequencies as high as possible, for example on high speed microprocessors. Nevertheless, the need arises to be able to perform measurements in low frequency ranges, for example in the frequency ranges of video devices such as plasma screens, of the order of 100 Hz (typically of the order of 60 Hz, 100 Hz, 200 Hz, 400 Hz, and 600 Hz). To allow measurements at low frequencies, some known devices include an electrical processing device having a bandwidth Afl as wide as possible, which is complex and expensive and is most often incompatible with obtaining a high gain of amplification and low noise (the thermal noise being in particular proportional to the square root of the bandwidth according to the Nyquist formula).

Other known devices also provide for several electrical treatment devices, each being adapted to a predetermined frequency range of the activity to be measured, for example a first electrical treatment device for low frequencies and second treatment device electric for high frequencies. Again, this solution is expensive and requires knowing beforehand the frequency range concerned. It requires to multiply the electrical processing devices to be able to perform measurements on the same electronic circuit in very different frequencies.

EP 864872 discloses a LVP process by successive use of two radiations, one of which is applied to the circuit to be tested while the other serves as a reference, and to report the measurements from these two radiations to minimize low frequency noise. due to temperature variations or misalignment of the incident laser spot. The laser beams are pulsed at 100 Mhz by optical modulators, and a single pulse is selected to perform optical sampling. This method therefore makes it possible to perform measurements only in very high frequency ranges. US2007 / 0002328 discloses an apparatus and method for wide bandwidth electrical signals using a modulated laser in an optical test system. This document aims to propose a system for improving the laser sounding of a circuit to be tested at high frequency by simplifying operations and minimizing the complexity and cost of the system. Since the operating frequency f _v of the circuit to be tested is much higher than the bandwidth of the photodetector, this document provides for modulating the laser source at a given frequency f _l5 which is the same frequency as f _v of the circuit under test , the radiation being disturbed by the circuit to be tested by a frequency modulation Af which is at a frequency much lower than the operating frequency of the circuit to be tested and which is in the bandwidth of the photodetector so that it can be detected by the latter . This document does not therefore relate to the problem of extracting a waveform of an activity occurring at low frequency, in particular in a frequency band at least partly below the bandwidth of the electrical treatment.

The invention therefore aims to overcome these drawbacks by proposing a method and an extraction device making it possible in a simple and inexpensive way to obtain a waveform of an activity occurring in a frequency band AfO at least partly less than the bandwidth Afl of said electrical treatment, and this reliably and faithfully (without degradation of the waveform).

The invention aims, for example, in particular at enabling the extraction of a waveform of an activity occurring in frequency ranges below 1 kHz, in particular of the order of or less than 100 Hz, with a electrical treatment whose bandwidth extends over frequencies above 1 MHz, in particular of the order of 100 MHz.

The invention is more particularly intended to provide such a method and such a device that make it possible to obtain this extraction with a single electrical treatment device. The invention also aims to allow the optimization of the electrical treatment device so that the latter has a high gain and low noise. The invention thus relates to a method of extracting a waveform of an activity occurring in a frequency band AfO in an electro-optical component, wherein:

an optical sounding of the electro-optical component is carried out by:

o application of at least one optical radiation beam, said probe beam, on an active region of said electro-optical component,

o detection of at least one optical radiation reflected by said active region, each reflected optical radiation being formed of an optical radiation, said carrier radiation, of periodic intensity on a fundamental frequency, said optical carrier fopt frequency, greater than the maximum frequency of the frequency band AfO of said electrical activity, said carrier radiation being modulated by variations induced by said active region and corresponding to said activity in said frequency band AfO,

an electrical treatment of each reflected optical radiation is carried out, in which:

at least one electrical detection signal at least partly representative of said activity is produced from each reflected optical radiation,

a reconstruction of said waveform is carried out from each electrical detection signal,

said electrical treatment being operational in a bandwidth Afl of predetermined frequency,

said electrical treatment delivering each electrical detection signal in the form of a signal comprising a periodic carrier of fundamental frequency corresponding to that of the carrier radiation, modulated by a modulation signal representative of said activity in said frequency band AfO, said reconstruction of said waveform comprising a demodulation of each electrical detection signal delivering a signal corresponding to said modulation signal representative of said waveform of said activity,

characterized in that

said electrical treatment is such that said frequency band AfO of said activity is at least partly lower than said passband Afl of said electrical treatment,

said optical carrier fopt frequency is chosen such that at least one of the frequency bands fl-AfO and fl + AfO is contained in the passband Afl of said electrical treatment.

Thus, the invention realizes an optical frequency transposition and makes it possible, by using a reflected optical radiation having an optical carrier (periodic variations in light intensity), of a fundamental frequency fopt greater than -in particular at least twice as much- as the maximum frequency fOmax of the frequency band AfO of said electrical activity, to choose an electrical treatment having a bandwidth Afl of small width and high frequency, with the benefit of a high gain and a low noise while allowing the Reliable, faithful and accurate extraction of a waveform in an AfO frequency band located at low frequencies.

Advantageously and according to the invention:

said carrier radiation is an optical radiation of continuous periodic intensity, especially with sinusoidal intensity variations of non-zero average value,

the periodic carrier of each electrical detection signal is a continuous periodic carrier, particularly sinusoidal. In particular, the carrier radiation is neither pulsed nor sampled. The same is true of the periodic carrier of each electrical detection signal.

Moreover, this carrier radiation of the reflected optical radiation can be obtained in various ways, by introducing at least one optical modulation between the optical radiation source of the probe beam and the reflected optical radiation applied to the electrical treatment. Preferably, advantageously and according to the invention, the carrier radiation is generated by modulating the probe beam. In addition, advantageously and according to the invention, the carrier radiation is generated by at least one modulation chosen from a mechano-optical modulation, an electro-optical modulation, an acousto-optical modulation, a magneto-optical modulation, an interferometric modulation. direct modulation of a power supply of a light source emitting said probe beam.

Moreover, different types of modulation can be envisaged to modulate the carrier radiation of the reflected optical radiation used in the electrical treatment, since this modulation is representative of said activity in the frequency band AfO. Nevertheless, initially, an electro-optical component generates a reflected optical radiation having a modulation of light intensity with respect to the probe beam. As a result, it is preferable to keep this type of amplitude modulation. Also, the electrical treatment, which is obtained for example by using at least one photodiode, does not modify the type of modulation of the reflected optical radiation. Accordingly, advantageously and according to the invention each reflected optical radiation is formed of amplitude modulated carrier radiation, said modulation signal is an amplitude modulation and said demodulation is an amplitude demodulation.

Preferably, advantageously and according to the invention, the bandwidth Afl of the electrical treatment is chosen to be separated from the frequency band AfO of said electrical activity. In addition, advantageously and according to the invention, the frequency band AfO of said electrical activity occurring in frequency ranges below 1 kHz -particularly between 50 Hz and 150 Hz; in particular of the order of 100 Hz or less than 100 Hz-, the bandwidth Afl of the electrical treatment extends over frequencies greater than 100 kHz-in particular greater than 1 MHz, in particular of the order of 100 MHz or more.

Furthermore, preferably, advantageously and according to the invention, the passband Afl of said electrical processing device and said optical carrier frequency fopt are chosen such that said fundamental fundamental frequency of the carrier of each electrical detection signal is greater than at 2 times the maximum frequency fOmax of the frequency band AfO of said electrical activity.

Furthermore, advantageously and according to the invention the bandwidth Afl of the electrical processing and said optical carrier frequency fopt are chosen such that said fundamental fundamental frequency of the carrier of each electrical detection signal is contained in the passband Afl of electrical treatment.

The invention applies equally well when the frequency band AfO of said electrical activity is not predetermined or exactly known (except knowing that it is at least partly lower than said passband Afl of said electrical treatment); indeed, in this case, advantageously and according to the invention, the fundamental frequency fopt optical carrier is preferably chosen so that the fundamental fl ow frequency is located in said passband Afl said electrical treatment so that the two bands of frequency fl-AfO and fl + AfO are both contained in the bandwidth Afl of said electrical treatment, this bandwidth Afl of said electrical treatment further having a width sufficient to be greater than 2. AfO. In this case, each electrical detection signal will indeed have a modulation signal representative of said activity and capable of being demodulated to enable the extraction of the waveform. The invention also extends to a device for implementing a method according to the invention.

The invention therefore also relates to a device for extracting a waveform of an activity occurring in an electro-optical component in a frequency band AfO, comprising:

an optical sounding device comprising:

an optical radiation source device arranged to be able to apply at least one optical radiation beam, called the probe beam, to an active region of said electro-optical component,

a device for detecting at least one optical radiation reflected by said active region,

the optical sounding device being adapted to generate each optical radiation reflected in the form of an optical radiation, called carrier radiation, of periodic intensity on a fundamental frequency, said optical carrier fopt frequency, greater than the maximum frequency of the frequency band AfO of said electrical activity, said carrier radiation being modulated by variations induced by said active region and corresponding to said activity in said frequency band AfO,

an electrical treatment device for each reflected optical radiation, comprising:

a transducing device producing, from each reflected optical radiation, at least one electrical detection signal at least partly representative of said activity,

a waveform reconstruction circuit capable of delivering a signal representative of said waveform from each electrical detection signal,

said electrical treatment device being operational in a bandwidth Afl of predetermined frequency, the electrical treatment device is adapted to deliver each electrical detection signal in the form of a signal comprising a periodic carrier of fundamental frequency corresponding to that of said optical modulation, modulated by a modulation signal in said frequency band AfO representative of said activity,

said waveform reconstruction circuit comprising a demodulator receiving each detection electric signal and delivering a signal corresponding to said modulation signal representative of said waveform of said activity,

characterized in that

the electrical treatment device is adapted so that said frequency band AfO of said activity is at least partly lower than said bandwidth Af1 of said electrical treatment device,

the optical sounding device is adapted so that the optical carrier frequency frequency is such that at least one of the frequency bands fl-AfO and fl + AfO is contained in the passband Afl of said electrical treatment device.

Advantageously and according to the invention, the optical sounding device is adapted to generate each carrier radiation in the form of an optical radiation of continuous periodic intensity-in particular with sinusoidal intensity variations of non-zero average value-and the device of Electrical processing is adapted to generate the periodic carrier of each electrical detection signal in the form of a continuous periodic carrier - especially sinusoidal -.

Furthermore, advantageously and according to the invention, the optical sounding device comprises at least one modulator of the probe beam. In addition, advantageously and according to the invention, the optical sounding device comprises at least one modulator chosen from a mechano-optical modulator, an electro-optical modulator, an acousto-optical modulator, a magneto-optical modulator, a interferometer modulator, a direct modulator of a power supply of a light source emitting said probe beam.

Also, advantageously and according to the invention, the optical sounding device is adapted to generate each reflected optical radiation in the form of amplitude modulated carrier radiation, in that the electrical treatment device is adapted to deliver each electrical detection signal in the form of an amplitude modulation, by said modulation signal, of said carrier, and in that said demodulator is an amplitude demodulator.

The invention also extends an extraction device characterized in that it is adapted for the implementation of all or part of the characteristics mentioned above or below in relation to an extraction method according to the invention. invention.

The invention also extends to a method implemented with a device according to the invention.

The invention applies in particular in the case where said electro-optical component is an electronic circuit, said activity being an electrical activity within this electronic circuit. It may be for example a VLSI integrated circuit (integration on a very large scale) and / or a flip-chip assembly type integrated circuit whose active areas are accessible only by the back of the substrate, or whatever. Said activity within the electronic circuit may for example be generated by a tester which supplies the electronic circuit with test vectors, in order to detect the presence of faults in the circuit.

It nevertheless applies also in the case where said electro-optical component is not itself an electronic circuit, and for example to an electro-optical crystal used in an electronic circuit test probe. It applies more generally since the activity within the electro-optical component makes it possible to modulate in a certain way the carrier radiation of the reflected optical radiation, this modulation being detectable by a transducing device providing an electrical detection signal as well. modulated according to a modulation signal that can be extracted from this electrical detection signal by demodulation.

The invention also applies particularly advantageously when said activity is repetitive, said modulation signal extracted by demodulation of each electrical detection signal itself being repetitive and repeatedly having said waveform. Advantageously and according to the invention, an average waveform is generated from the different waveforms successively extracted in said modulation signal.

In a preferred embodiment, advantageously and according to the invention, the electrical treatment delivers a single electrical detection signal (for example the electrical treatment device comprises a single photodiode). However, nothing prevents the simultaneous realization of several electrical treatments, possibly with different transduction devices, the same reflected optical radiation or several reflected optical radiation, from the same probe beam or from several probe beams.

It should be noted that the invention has the particular advantage of allowing the use of an optical radiation source device that is not necessarily stabilized, since the reflected optical radiation incorporates high frequency carrier variations.

The invention also relates to a method and a device characterized in combination by all or some of the characteristics mentioned above or below.

Other objects, features and advantages of the invention will appear on reading the following non-limiting description which refers to the appended figures in which:

FIG. 1 is a block diagram of a device according to one embodiment of the invention embodying a method according to the invention,

FIG. 2 is an example of a frequency spectrum illustrating the operation of the invention, FIGS. 3a to 3d are examples of waveforms extracted by a method according to the invention for different frequencies.

The device according to the invention shown in FIG. 1 comprises an electronic circuit 11 to be tested placed on a tester 12. A source 13 of optical radiation, which may be a laser source, a laser diode, or a non-coherent light source (LED ) emits an optical radiation beam 20, referred to as a probe beam, directed towards an active zone of the electronic circuit 11. This probe beam passes through an optical modulator 14 which applies continuous, preferably sinusoidal, non-linear periodic variations. zero, at the light intensity of the beam 20 probe.

The optical modulator 14 delivers a beam 21 of a carrier radiation of periodic intensity on a fundamental frequency fopt optical carrier. This carrier beam 21 passes through a semi-reflecting mirror 15 to be applied to the active area of the electronic circuit 11 to be tested. This active zone is the seat of a low-frequency electrical activity 22, in a frequency band AfO, for example a voltage variation. By electro-optical effect, this electrical activity modulates the optical radiation reflected by the active zone and deflected by the semi-reflecting mirror towards a photodiode 16. Examples of the appearance of electrical activity and light intensity reflected optical radiation 23 are shown in FIG.

The output of the photodiode 16 provides an electrical signal which is amplified by an amplifier 17, the assembly having a bandwidth Afl. The amplifier 17 must be an amplifier with a low noise factor (for example less than 2 dB). The amplifier 17 delivers a detection electric signal 24 in the form of a signal comprising a periodic carrier of fundamental frequency corresponding to that of the carrier radiation 21, modulated by a modulation signal representative of said electrical activity 22 in said band. of frequency AfO. Such a photodiode 16 constitutes a transduction device that provides an electrical signal that is exactly representative of the optical radiation that it receives, at the same frequency, so that fl = fopt. The photodiode 16 must be chosen to be able to present a distortion-free response for this frequency, and the source 13 of optical radiation is also chosen so that the reflected optical radiation 23 does not saturate the photodiode 16.

This electrical detection signal 24 delivered by the photodiode 16 is demodulated by an amplitude demodulator 18 which suppresses the periodic carrier and delivers the modulation signal to an oscilloscope 19 which makes it possible to visualize the waveform thus extracted. Preferably, the tester 12 is connected to the oscilloscope 19 to deliver a synchronization trigger signal.

The optical modulator 14 is for example advantageously a Mach-Zehnder interferometer. The optical modulator 14 may also be an absorption modulator (variation of the absorption coefficient of a material) or a refractive modulator (variation of the refractive index of a material). It may as well be an alternative variant of a mechano-optical modulator ("chopper" with a perforated disc and / or a rotating mirror), of an electro-optical modulator (variation of the polarization of a crystal under the effect a variable electric field), an acousto-optical modulator, a magneto-optical modulator, an interferometric modulator, a direct modulator of a power supply of the light source 13 emitting said probe beam.

For example, the source 13 of optical radiation and the photodiode 16 and at least a portion of the amplifier 17 are integrated in an electro-optical sounding device such as that marketed under the reference "EO Probing Unit" by the company Hamamatsu Photonics KK, Hamamatsu City, Japan (www.hamamatsu.com). The photodiode of this device is an InGaAs photodiode whose bandwidth extends between 100 kHz and 1 GHz. Preferably, a low noise complementary amplifier is used at the output of this device, to perform the amplification function 17. For example, a MITEQ ® AU-1291 amplifier marketed by MITEQ Inc., Hauppauge, NY, is used. USA (www.miteq.com) whose bandwidth extends between 1 kHz and 500 MHz, for a gain of 63 dB and a noise factor of 1.4 dB.

The demodulator 18 may for example be formed, as well as the oscilloscope 19, by a signal analyzer marketed under the reference E4405B by Agilent Technologies France, Les ULIS, France with the AM demodulation option. It may just as well be any other amplitude demodulator.

As can be seen in FIG. 2, the pass band Afl of the electrical treatment (photodiode 16 and amplifier 17) does not cover the entire frequency band AfO of the electrical activity when the latter is in the low frequencies. The insertion of an optical carrier 21 in the reflected optical radiation makes it possible to transpose the electrical activity around the fundamental fl = fopt frequency of the carrier of the electrical detection signal, so that the electrical treatment is applied to the the entire electrical activity thus transposed. It should be noted that it suffices in practice for at least one of the frequency bands fl-AfO and fl + AfO to be contained in the pass band Afl of the electrical processing so that the waveform can be extracted by demodulation of the electrical detection signal 24 delivered to the output of the amplifier 17.

It should also be noted that it is possible to use a transducing device other than a photodiode 16, for example a phototransistor or a photomultiplier, and possibly a transducing device that provides an electrical detection signal for the carrier at a desired speed. frequency different from that of the carrier radiation of the reflected optical radiation.

EXAMPLE:

An example of waveform extraction was performed under the following conditions:

source 13 of optical radiation: laser diode at 1340 nm,

optical modulator 14: Mach-Zehnder modulator (APE) marketed by the company JDS Uniphase Corporation Milpitas, CA, USA, electronic circuit to be tested: analog part of a STM32 microcontroller (M4 core, 90 nm technology) from the company STMIC OELECT ONICS, Paris, France,

photodiode 16: an electro-optical sounding device such as the one sold under the reference "EO Probing Unit" by Hamamatsu Photonics K.K., Hamamatsu City, Japan (www.hamamatsu.com),

amplifier 17: MITEQ® amplifier AU-1291 marketed by MITEQ Inc., Hauppauge, NY, USA (www.miteq.com),

demodulator 18 and oscilloscope 19: MITEQ® amplifier AU-1291 marketed by MITEQ Inc., Hauppauge, NY, USA (www.miteq.com) signal analyzer marketed under the reference E4405B by Agilent Technologies France, Les ULIS , France, with the AM demodulation option.

The probe beam is applied to a node of the microcontroller in which electrical voltage variations 22 have been generated whose appearance corresponds to that shown in FIG. 1, and at different frequencies f0: 981 Hz, 661 Hz, 132 Hz, and 66 Hz. Microcontroller power supply voltages are 3.3 V (input / output) and 1.8 V for the core.

FIGS. 3a to 3d represent the extracted waveforms visualized on the oscilloscope 19 respectively for the different values of the frequency f0. As can be seen, the invention makes it possible to extract waveforms with very good fidelity, without distortion, even for very low frequencies.

Claims

1 / - A method of extracting a waveform of an activity occurring in an AfO frequency band in an electro-optical component (1 1), wherein:

an optical sounding of the electro-optical component is carried out by:

o application of at least one optical radiation beam, said probe beam, to an active region of said electro-optical component (1 1),

o detection of at least one optical radiation (23) reflected by said active region, each reflected optical radiation (23) being formed of an optical radiation, said carrier radiation, of periodic intensity on a fundamental frequency, said frequency fopt optical carrier, greater than the maximum frequency of the frequency band AfO of said electrical activity, said carrier radiation being modulated by variations induced by said active region and corresponding to said activity in said frequency band AfO,

an electrical treatment of each reflected optical radiation (23) is carried out, in which:

at least one electrical detection signal (24) at least partly representative of said activity is produced from each reflected optical radiation (23),

said electrical treatment delivering each electrical detection signal (24) in the form of a signal comprising a periodic carrier of fundamental frequency corresponding to that of the carrier radiation, modulated by a modulation signal representative of said activity in said band of AfO frequency, said reconstruction of said waveform comprising a demodulation of each electrical detection signal (24) delivering a signal corresponding to said modulation signal representative of said waveform of said activity,

characterized in that

21 - Process according to claim 1, characterized in that:

said carrier radiation is an optical radiation of continuous periodic intensity,

the periodic carrier of each electric detection signal (24) is a continuous periodic carrier.

3 / - Method according to any one of claims 1 or 2, characterized in that:

said carrier radiation is an optical radiation with sinusoidal intensity variations of non-zero average value,

the periodic carrier of each electrical detection signal (24) is a sinusoidal carrier.

4 / - Method according to any one of claims 1 to 3, characterized in that the carrier radiation is generated by modulation of the beam (20) probe.

5 / - Method according to any one of claims 1 to 4, characterized in that the carrier radiation is generated by at least one modulation selected from a mechano-optical modulation, a modulation electro-optical, acousto-optical modulation, magneto-optical modulation, interferometric modulation, direct modulation of a power supply of a light source emitting said probe beam.

6 / - Method according to any one of claims 1 to 5, characterized in that each reflected optical radiation (23) is formed of amplitude modulated carrier radiation, in that said modulation signal is an amplitude modulation and in that said demodulation is an amplitude demodulation.

7 / - Method according to any one of claims 1 to 6, characterized in that the bandwidth Afl of the electrical treatment is chosen to be disjoined from the frequency band AfO of said electrical activity.

8 / - Method according to any one of claims 1 to 7, characterized in that the frequency band AfO of said electrical activity occurring in frequency ranges below 1 kHz, the bandwidth Afl of the electrical treatment extends at frequencies above 100 kHz.

91 - Process according to any one of claims 1 to 8, characterized in that the bandwidth Afl of the electrical treatment and said fopt optical carrier frequency are chosen such that said fundamental fundamental frequency of the carrier of each signal (24). ) electrical detection is contained in the bandwidth Afl of the electrical treatment.

10 / - Method according to any one of claims 1 to 9, characterized in that said component (1 1) electro-optics is an electronic circuit and in that said activity is an electrical activity within this electronic circuit.

1 1 / - Device for extracting a waveform of an activity occurring in an electro-optical component (1 1) in a frequency band AfO, comprising:

an optical sounding device (13, 14, 15) comprising: an optical radiation source device (13) arranged to be able to apply at least one optical radiation beam, said probe beam, to an active region of said electro-optical component (1 1),

a device (15, 16) for detecting at least one optical radiation (23) reflected by said active region,

the optical sounding device (13, 14, 15) being adapted to generate each optical radiation (23) reflected in the form of an optical radiation, called carrier radiation, of periodic intensity on a fundamental frequency, called the fopt frequency; optical carrier, greater than the maximum frequency of the frequency band AfO of said electrical activity, said carrier radiation being modulated by variations induced by said active region and corresponding to said activity in said frequency band AfO,

a device (16, 17, 18, 19) for electrical treatment of each reflected optical radiation, comprising:

a transducing device (16) producing, from each reflected optical radiation (23), at least one electrical detection signal (24) at least partly representative of said activity,

a waveform reconstruction circuit (18, 19) capable of delivering a signal representative of said waveform from each electrical detection signal,

said electrical treatment device (16, 17, 18, 19) being operational in a bandwidth Afl of predetermined frequency,

the electrical treatment device is adapted to deliver each electric detection signal (24) in the form of a signal comprising a periodic carrier of fundamental frequency corresponding to that of said optical modulation, modulated by a modulation signal in said band; an AfO frequency representative of said activity, said waveform reconstruction circuit (18, 19) comprising a demodulator (18) receiving each detection electric signal (24) and delivering a signal corresponding to said modulation signal representative of said waveform of said activity,

characterized in that

the electrical treatment device (16, 17, 18, 19) is adapted so that said frequency band AfO of said activity is at least partly lower than said bandwidth Af1 of said electrical treatment device,

- the optical pick-up device (13, 14, 15) is adapted so that the optical carrier frequency frequency is such that at least one of the frequency bands fi -AfO and fi + AfO is contained in the passband Afl of said electric treatment device.

12 / - Device according to claim 1 1, characterized in that the device (13, 14, 15) of optical sounding is adapted to generate each carrier radiation in the form of optical radiation of continuous periodic intensity, and in that the electrical processing device (16, 17, 18, 19) is adapted to generate the periodic carrier of each electrical detection signal (24) as a continuous periodic carrier.

13 / - Device according to any one of claims 1 1 or

12, characterized in that the optical probing device (13, 14, 15) is adapted to generate each carrier radiation in the form of an optical radiation with sinusoidal intensity variations of non-zero average value, and in that the electrical processing device (16, 17, 18, 19) is adapted to generate the periodic carrier of each electrical detection signal in the form of a sinusoidal carrier.

14 / - Device according to any one of claims 1 1 to

13, characterized in that the optical probing device (13, 14, 15) comprises at least one modulator (14) of the probe beam selected from a mechano-optical modulator, an electro-optical modulator, an acousto-optical modulator, a modulator magneto-optical, an interferometer modulator, a direct modulator of a power supply of a light source emitting said probe beam.

15 / - Device according to any one of claims 1 1 to

14, characterized in that the optical pick-up device (13, 14, 15) is adapted to generate each reflected optical radiation in the form of amplitude-modulated carrier radiation, in that the device (16, 17, 18, 19) electrical processing apparatus is adapted to deliver each electrical detection signal (24) in the form of an amplitude modulation, by said modulation signal, of said carrier, and in that said demodulator (18) is a demodulator of amplitude.

16 / - Device according to any one of claims 1 1 to

15, characterized in that the electrical treatment device (16, 17, 18, 19) is adapted so that the frequency band AfO of said electrical activity occurring in frequency ranges below 1 kHz, the bandwidth Afl of the Electrical treatment extends over frequencies above 100 kHz.