CN110187177A - A kind of the opto-electronic device frequency response test device and method of All-in-One - Google Patents

Abstract

The invention claims to protect an all-in-one optoelectronic device frequency response testing device and method. The invention is composed of a laser, a frequency-shifting heterodyne interference module, a photodetector to be tested and a spectrum analysis module, wherein the frequency-shifting heterodyne interference module is composed of an electro-optical modulator to be tested and a frequency shifter, and is respectively placed in the interference module In the upper and lower arms of Mach-Zehnder, the laser, the frequency-shifting heterodyne interference module and the photodetector to be tested are optically connected in sequence, the microwave signal source is electrically connected to the input electrode of the electro-optic modulator to be tested, and the photodetector to be tested The output terminal is electrically connected to the spectrum analysis module; when the microwave signal source is driven by two different output voltages at the same operating frequency, the power ratio of the corresponding components is obtained through the spectrum analysis module, and the power ratio of the corresponding components is obtained through the two different drives. The ratio is used to realize the frequency response test of the electro-optic modulator to be tested, and then back calculate the frequency response of the photodetector to be tested, and finally realize the self-calibration test of the frequency response.

Description

An all-in-one optoelectronic device frequency response testing device and method

technical field

The invention belongs to the technical field of optoelectronics, and in particular relates to an all-in-one optoelectronic device frequency response testing device and method.

Background technique

With the advent of 5G mobile communication, people's demand for communication speed and data capacity has shown explosive growth. At present, the rapid development of optical fiber communication system is the basic guarantee for the promotion of 5G mobile communication in the future. As a basic component of optical fiber communication system - optoelectronic devices, its characteristic parameters are the key to determine the communication capacity, bandwidth and speed. At the same time, the realization of optoelectronic Accurate characterization of device characteristic parameters plays a vital role in the development, design, manufacture and optimization of optoelectronic devices, so the study of optoelectronic device characteristic parameters is particularly important.

The current method of measuring the frequency response of optoelectronic devices is based on the different types of devices to be tested, and the test methods are also different. Among them, in the optical domain test method, the spectral analysis method can realize the measurement of the frequency response of the electro-optic modulator, (Y.Q.Shi, L.S.Yan, A.E.Willner, "High-speed electrooptic modulator characterization using optical spectrum analysis," Journal of Lightwave Technology, 2003, 21(10):2358-2367), however, the measurement accuracy of this scheme depends heavily on the resolution of the spectrum analyzer, and there are usually problems of low measurement frequency resolution and low precision. In addition, the spectral analysis method cannot realize the photodetector Frequency response test; in the electrical domain measurement method, the frequency sweep method (Y.Q.Heng, M.Xue, W.Chen, S.L.Han, J.Q.Liu, and S.L.Pan, “Large-dynamic frequency frequency measurement for broadband electro-optic phase modulators , "IEEE Photonics Technology Letters, 2019, 31(4): 291-294. D.A. Humphreys, "Integrated-optic system for high-speed photodetector bandwidth measurements," Electronics Letters, 1989, 25(23): 1555-1557.) fully Utilizing the high-precision test characteristics of vector network analyzers, high-precision relative frequency response testing of optoelectronic devices can be achieved. However, additional calibration is required and the process is complicated; the frequency-shifting heterodyne method (S.J.Zhang, C.Zhang, H.Wang , X.H.Zou, Y.L.Zhang, Y.Liu, and J.E.Bowers, "Self-calibrated microwave characterization of high-speed optoelectronic devices by heterodyne spectrum mapping," Journal of Lightwave Technology, 35(10), 1952-1961.) is using heterodyne The principle of interference, by configuring the frequency relationship of two modulation signals, achieves high-precision, self-calibrating absolute frequency response testing of optoelectronic devices. However, this solution requires an additional auxiliary broadband microwave source and broadband modulator to eliminate other components in the system. The influence of frequency response, the system pin big.

Contents of the invention

The present invention aims to solve the above problems of the prior art. An all-in-one optoelectronic device frequency response testing device and method for realizing multi-device and multi-parameter all-in-one optoelectronic device characteristic parameters with high resolution, high precision, low cost, and self-calibration electrical domain measurement is proposed. Technical scheme of the present invention is as follows:

An all-in-one frequency response testing device for optoelectronic devices, which includes a laser, a signal source, a frequency-shifting heterodyne interference module, a photodetector to be tested, and a spectrum analysis module; wherein, the frequency-shifting heterodyne interference module is composed of The electro-optic modulator and the frequency shifter are composed of an electro-optic modulator and a frequency shifter, and are respectively placed in the upper and lower arms of the Mach-Zehnder interference module of the frequency-shifting heterodyne; the signal source is electrically connected to the input electrode terminal of the electro-optic modulator to be tested; the laser , the frequency-shifting heterodyne interference module, and the photodetector to be tested are optically connected in sequence; the output end of the photodetector to be tested is electrically connected to the spectrum analysis module, and the laser is used for lasing DC light waves, and the signal source is used For generating sinusoidal microwave signals, the frequency-shifting heterodyne interference module is used to realize the heterodyne beat frequency of light waves, the photodetector to be tested is used to detect the optical signal, and the spectrum analysis module is used to analyze the spectral information of the output signal of the photodetector. The electro-optic modulator is used to load the sinusoidal microwave signal to the DC light wave, and the frequency shifter is used to realize the frequency shift of the DC light wave. The signal source is set to be driven by two different output voltages at the same operating frequency, and the corresponding component is obtained through the spectrum analysis module. The power ratio, through the ratio of the power ratio under two different driving conditions, realizes the frequency response test of the electro-optic modulator to be tested, and then back-calculates the frequency response of the photodetector to be tested.

Further, the electro-optic modulator to be tested is an electro-optic phase modulator or an electro-optic intensity modulator, which is used to modulate the phase or intensity of the direct current light wave.

Further, when the electro-optic modulator to be tested is an electro-optic phase modulator, the electric field E _PM of the modulated optical signal is expressed as:

Wherein, A ₁ is the amplitude of the optical carrier in the upper arm, m is the modulation coefficient of the electro-optic modulator to be tested, J _p ( ) is the first kind of Bessel function of the pth order, and j is a complex number;

The frequency response of the detector to be tested at a relatively fixed low frequency f _s is:

Among them, J ₀ (·) is the 0th order Bessel function of the first kind, J ₁ (·) is the 1st order Bessel function of the first kind, R(f _s ) and R(f ₁ ±f _s ) are the responsivity of the photodetector to be tested at frequencies f _s and f ₁ ±f _s , respectively.

Further, when the electro-optic modulator to be tested is an electro-optic intensity modulator, the electric field E _MZM of the modulated optical signal is expressed as:

In the formula, φ is the phase difference caused by the bias voltage;

Obtain the frequency response at the relatively fixed low frequency f _s of the detector to be tested as:

A method for testing the frequency response of an optoelectronic device based on the device, comprising the following steps:

(1) The signal source generates a microwave signal with a frequency of f ₁ and an amplitude of V _s , which is loaded on the light wave through the electro-optic modulator to be tested, and the modulated signal is combined with the optical carrier after the frequency shift by the frequency shifter f _s , The combined optical signal is sent to the photodetector for photoelectric conversion to obtain the mixed frequency signal, and the amplitude ratio of the frequency components f _s and f ₁ ±f _s in the mixed frequency signal is recorded by the spectrum analysis module;

(2) Without changing the frequency of the microwave signal source, change the amplitude of the output microwave signal to V _s '=rV _s , and use the spectrum analysis module to record the amplitudes of the frequency components f _s and f ₁ ±f _s in the mixed frequency signal value ratio;

(3) Eliminate the frequency response of the photodetector to be tested by the ratio of the two amplitude ratios of steps (1) and (2). Since the amplitude ratio r of the two modulation signals is known, the electro-optic modulator to be tested is obtained The modulation factor m;

(4) After obtaining the modulation coefficient of the electro-optic modulator to be tested, the responsivity R of the photodetector to be tested is calculated inversely through the frequency component amplitude ratio;

(5) Change the frequency f ₁ of the microwave signal source and repeat the above process to obtain the frequency responses of the electro-optic modulator to be tested and the photodetector to be tested at different frequencies, so as to realize the self-calibration test of the frequency response of the all-in-one optoelectronic device.

Further, the step (1) utilizes the spectrum analysis module to record the frequency component f _s and the amplitude ratio of f ₁ ± f _s in the frequency mixing signal, which is:

In the formula, H represents the amplitude ratio of frequency components f _s and f ₁ ±f _s in the mixed frequency signal, M is a function of m, and R is the responsivity of the photodetector to be tested.

Further, the step (2) changes the amplitude of the output microwave signal to V _s '=rV _s without changing the frequency of the microwave signal source, and uses the frequency spectrum analysis module to record the frequency components f _s and f in the mixed frequency signal The amplitude ratio of ₁ ±f _s is:

In the formula, M' is a function about r and m;

Further, the amplitude ratio r≠1 of the two microwave signal drives.

Advantage of the present invention and beneficial effect are as follows:

(1) The device of the present invention adopts a frequency-shifted heterodyne interference structure, which avoids the jitter problem that the interference structure is easily caused by the external environment, and realizes a stable frequency response test structure of optoelectronic devices.

(2) The present invention uses the principle of two different microwave signal voltage drives without dismantling the test system, and can eliminate the frequency response of additional devices in the test system through the ratio of the required mixing components, and realizes electro-optical modulation at the same time self-calibration test of the frequency response of detectors and photodetectors.

(3) The frequency response of different types of optoelectronic devices can be tested with only the same test system. Compared with the current frequency-shifting heterodyne interferometry, the self-calibration test does not require additional broadband microwave sources and broadband modulators, and has a simple test structure. With the advantages of low cost and low cost, a low-cost, all-in-one self-calibration test is realized.

(4) The present invention utilizes the principle of frequency-shifting heterodyne interference to map the heterodyne beat frequency of the light wave sideband information to the electrical domain with high-precision analysis capability for analysis and detection, and only needs to tune the frequency sweep interval of the frequency sweep test, High-resolution frequency response testing of optoelectronic devices can be realized.

Description of drawings

Fig. 1 is a connection structure diagram of an all-in-one optoelectronic device frequency response testing device according to a preferred embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and in detail below with reference to the drawings in the embodiments of the present invention. The described embodiments are only some of the embodiments of the invention.

The technical scheme that the present invention solves the problems of the technologies described above is:

As shown in Figure 1, an all-in-one frequency response testing device for optoelectronic devices includes a laser, a frequency-shifting heterodyne interference module, a photodetector to be tested, and a spectrum analysis module; wherein the frequency-shifting heterodyne interference module consists of a The electro-optic modulator and frequency shifter are composed of the upper and lower arms of the interference module; the microwave signal source is electrically connected to the electro-optic modulator to be tested; the laser, the frequency-shifting heterodyne interference module, and the photodetector to be tested Optical connection in sequence; electrical connection between the photodetector to be tested and the spectrum analysis module; the electro-optic modulator to be tested can be an electro-optic phase modulator or an electro-optic intensity modulator.

The testing principle and method of the frequency response of an all-in-one optoelectronic device of the present invention are as follows:

The optical carrier with the frequency f ₀ emitted by the laser enters the frequency-shifted heterodyne interference module, and the optical carrier on the upper arm of the interference module enters the electro-optic modulator to be tested, and the sinusoidal signal v(t)=V _s sin2πf generated by the microwave signal source ₁ t for electro-optic modulation.

(1) When the electro-optic modulator to be tested is an electro-optic phase modulator, the electric field E _PM of the modulated optical signal is expressed as:

Among them, A ₁ is the amplitude of the optical carrier in the upper arm, m(f ₁ ) is the modulation coefficient of the electro-optic modulator under test at the modulation frequency f ₁ , and J _p (·) is the first-type Bessel of the pth order Err function, j is a complex number.

The optical carrier in the lower arm of the interference module enters the frequency shifter, and the optical field of the optical carrier after frequency shift f _s is:

The combined optical signal output by the interference arm is detected by the photodetector to be tested, and the output photocurrent is:

Through the spectrum analysis module, the amplitudes corresponding to f ₁ ± f _s and f _s in the mixed frequency electrical signal are:

i(f ₁ ±f _s )＝2A ₁ A ₂ J ₁ [m(f ₁ )]R(f ₁ ±f _s ) (4a)

i(f _s )＝2A ₁ A ₂ J ₀ [m(f ₁ )]R(f _s ) (4b)

The magnitude ratio of the two mixing components is:

Adjust the amplitude of the modulation signal to be V _s '=rV _s , and similarly obtain the amplitude ratio of the two mixing components as:

The ratio of the two amplitude ratios is:

Solving formula (7), the modulation coefficient m of the phase modulator to be tested can be obtained, and the value of m can be substituted into formula (5), and the frequency response of the relatively fixed low frequency f _s of the detector to be tested can be obtained as follows:

(2) When the electro-optic modulator to be tested is an electro-optic intensity modulator (in the form of a Mach-Zehnder modulator), the electric field E _MZM of the modulated optical signal is expressed as:

In the formula, φ is the phase difference caused by the bias voltage.

Similarly, through the spectrum analysis module, the amplitude ratios of the two different power drives are:

The ratio of the two amplitude ratios is:

When φ ₁ = 0, φ ₂ = π, solve the formula (11), the modulation coefficient m of the intensity modulator to be tested can be obtained, and the value of m can be substituted into the formula (10a), and the relatively fixed low frequency f of the detector to be tested can be obtained The frequency response at _s is:

Therefore, in a fixed test system, the present invention can realize the self-calibration test of the frequency response of various optoelectronic devices.

Example

The output power of the laser is 10mW, and the optical carrier frequency is f ₀ =193THz (wavelength is about 1550nm). The microwave signal source generates a sinusoidal signal with a frequency of f ₁ = 20GHz to modulate the electro-optical modulator to be tested. In the lower arm of the frequency-shifting heterodyne interference module, the frequency shift of the optical carrier is 70MHz, and the coupled output signals of the upper and lower arms pass through the The photodetector detects, and the output photocurrent is analyzed by the spectrum analysis module. The power driven by two different signals is 10dBm and 4dBm respectively. At this time, the voltage amplitude ratio of the driving signal is r=0.5. (1) During the phase modulator and photodetector frequency response test, the amplitude ratios of the mixed frequency signals driven by two different signals are H=-16.52dB and H'=-22.65dB respectively, then the ratio of the two amplitude ratios is 6.14dB, obtained by the formula (7), the modulation coefficient of the phase modulator to be tested at the frequency of 20GHz is m=0.371, brought into the formula (8) to obtain the relative fixed low frequency f of the photodetector to be tested at the frequency of 20GHz The relative frequency response at _s = 70MHz is -2.04dB; (2) During the frequency response test of the Mach-Zehnder modulator and photodetector, when the power driven by the signal is 10dBm and the phase difference caused by the bias voltage is 0, The amplitude ratio of the mixed frequency signal is H=-21.56dB, when the power driven by the signal is 4dBm, and the phase difference caused by the bias voltage is π, the amplitude ratio of the mixed frequency signal is H'=17.53dB, then the two amplitudes Ratio ratio is-39.09dB, can obtain by formula (11), and the modulation factor of the phase modulator to be tested is m=0.421 at the frequency 20GHz place, is brought into formula (10a) and can obtain the photodetector to be tested at the frequency 20GHz place The relative frequency response at a relatively fixed low frequency f _s =70 MHz is -2.01 dB.

The above embodiments should be understood as only for illustrating the present invention but not for limiting the protection scope of the present invention. After reading the contents of the present invention, skilled persons can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims (8)

1. An all-in-one optoelectronic device frequency response testing device, characterized in that it includes a laser, a signal source, a frequency-shifting heterodyne interference module, a photodetector to be tested and a spectrum analysis module; wherein the frequency-shifting heterodyne The interference module is composed of an electro-optic modulator to be tested and a frequency shifter, and is respectively placed in the upper and lower arms of the Mach-Zehnder interference module of frequency shifting heterodyne; the signal source is electrically connected to the input electrode terminal of the electro-optic modulator to be tested. connection; the laser, the frequency-shifting heterodyne interference module, and the photodetector to be tested are optically connected in sequence; the output terminal of the photodetector to be tested is electrically connected to the spectrum analysis module, and the laser is used to generate DC light waves , the signal source is used to generate sinusoidal microwave signals, the frequency-shifting heterodyne interference module is used to realize the heterodyne beat frequency of light waves, the photodetector to be tested is used to detect the optical signal, and the spectrum analysis module is used to analyze the output signal of the photodetector Spectrum information, the electro-optic modulator to be tested is used to load the sinusoidal microwave signal to the DC light wave, the frequency shifter is used to realize the frequency shift of the DC light wave, the signal source is set to be driven by two different output voltages at the same operating frequency, and obtained through the spectrum analysis module The power ratio of the corresponding components is compared through the ratio of the power ratios under two different driving conditions to realize the frequency response test of the electro-optic modulator to be tested, and then back-calculate the frequency response of the photodetector to be tested. 2. A kind of all-in-one optoelectronic device frequency response testing device according to claim 1, characterized in that, the electro-optic modulator to be tested is an electro-optic phase modulator or an electro-optic intensity modulator, which is used for direct current light waves Phase or intensity modulation. 3. a kind of all-in-one optoelectronic device frequency response testing device according to claim 2, is characterized in that, when electro-optic modulator to be tested is electro-optic phase modulator, modulation light signal electric field E is _expressed as: Among them, A ₁ is the amplitude of the optical carrier in the upper arm, m(f ₁ ) is the modulation coefficient of the electro-optic modulator under test at the modulation frequency f ₁ , and J _p (·) is the first-type Bessel of the pth order Er function, j is a complex number; The frequency response of the detector to be tested at a relatively fixed low frequency f _s is: Among them, J ₀ (·) is the 0th order Bessel function of the first kind, J ₁ (·) is the 1st order Bessel function of the first kind, R(f _s ) and R(f ₁ ±f _s ) are the responsivity of the photodetector to be tested at frequencies f _s and f ₁ ±f _s , respectively. 4. a kind of all-in-one optoelectronic device frequency response testing device according to claim 3, is characterized in that, when electro-optic modulator to be tested is electro-optic intensity modulator, modulated optical signal electric field E _MZM is expressed as: In the formula, φ is the phase difference caused by the bias voltage; Obtain the frequency response at the relatively fixed low frequency f _s of the detector to be tested as: 5. A method for testing the frequency response of an optoelectronic device based on the device according to one of claims 1-4, characterized in that it comprises the following steps: (1) The signal source generates a microwave signal with a frequency of f ₁ and an amplitude of V _s , which is loaded on the light wave through the electro-optic modulator to be tested, and the modulated signal is combined with the optical carrier after the frequency shift by the frequency shifter f _s , The combined optical signal is sent to the photodetector for photoelectric conversion to obtain the mixed frequency signal, and the amplitude ratio of the frequency components f _s and f ₁ ±f _s in the mixed frequency signal is recorded by the spectrum analysis module; (2) Without changing the frequency of the microwave signal source, change the amplitude of the output microwave signal to V _s '=rV _s , and use the spectrum analysis module to record the amplitudes of the frequency components f _s and f ₁ ±f _s in the mixed frequency signal value ratio; (3) Eliminate the frequency response of the photodetector to be tested by the ratio of the two amplitude ratios of steps (1) and (2). Since the amplitude ratio r of the two modulation signals is known, the electro-optic modulator to be tested is obtained The modulation factor m; (4) After obtaining the modulation coefficient of the electro-optic modulator to be tested, the responsivity R of the photodetector to be tested is calculated inversely through the frequency component amplitude ratio; (5) Change the frequency f ₁ of the microwave signal source and repeat the above process to obtain the frequency responses of the electro-optic modulator to be tested and the photodetector to be tested at different frequencies, so as to realize the self-calibration test of the frequency response of the all-in-one optoelectronic device. 6. optoelectronic device frequency response test method according to claim 5, is characterized in that, Described step (1) utilizes frequency spectrum analysis module to record the amplitude ratio of frequency component f _s and f ₁ ± f _s in the frequency mixing signal, for: In the formula, H represents the amplitude ratio of frequency components f _s and f ₁ ±f _s in the mixed frequency signal, M is a function of m, and R is the responsivity of the photodetector to be tested. 7. optoelectronic device frequency response test method according to claim 5, is characterized in that, described step (2) changes the amplitude of output microwave signal to be V _s '=rV under the situation of not changing microwave signal source frequency _s , use the frequency spectrum analysis module to record the frequency component f _s and the amplitude ratio of f ₁ ± f _s in the mixed signal, which is: In the formula, M' is a function about r and m; 8. The method for testing the frequency response of an optoelectronic device according to any one of claims 5-7, wherein the amplitude ratio r≠1 of the two microwave signal drives.