High dynamic extinction ratio narrow laser pulse generation device

Abstract

The utility model discloses a high dynamic extinction ratio narrow laser pulse generation device, which comprises a driver, a laser, an optical transmission unit, an electro-optic intensity modulator, a reflection unit and a light amplification unit. Wherein the laser is driven by the driver to directly generate a narrow laser pulse with a relatively high dynamic extinction ratio, then the narrow laser pulse is subjected to intensity modulation twice by virtue of the combination of the electro-optical intensity modulator and the reflection unit so as to improve the dynamic extinction ratio, and finally, the laser pulse with both the high dynamic extinction ratio and the narrow pulse width can be obtained. Compared with an existing pulse light generating device, the laser pulse generating device has the advantages of being smaller in size, wider in bandwidth, lower in price, smaller in power consumption and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to laser sensing and laser radar technical field, concretely relates to a high dynamic extinction ratio narrow laser pulse generation device. BACKGROUND

[0002] Pulse laser has good beam quality, high peak power and carries time information. When the pulse light is transmitted to the optical fiber or free space, the subtle changes in the transmission path will change the amplitude, polarization and phase characteristics of the pulse light. Due to the reflection and scattering effect of light, the pulse light carrying path information is returned to the detection end for detection, so that the distribution of particulate matter, aerosol, temperature and vibration in the transmission path can be known, and thus it is widely used in the fields of laser sensing and laser radar.

[0003] In the field of laser sensing and laser radar, the most concerned indicators are measurement distance and distance resolution, wherein the distance resolution mainly depends on the pulse width of the pulse light, and the measurement distance mainly depends on the dynamic extinction ratio of the pulse light. The dynamic extinction ratio of the pulse light refers to the ratio of the peak power corresponding to the maximum light power to the peak power corresponding to the minimum light power, wherein: the maximum light power determines the farthest distance that can be detected in the far field; the minimum light power determines the nearest distance that can be detected in the near field, because the light returned by the pulse peak and the extinction position in the near field region is relatively strong, the power saturation effect of the detector itself will cause the signal-to-noise ratio of the detected signal to be too low to be detected. Therefore, in order to improve the simultaneous detection capability of laser radar and laser sensing in the near field and the far field, it is particularly important to obtain pulse light with high dynamic extinction ratio.

[0004] Figure 1 A typical scheme for generating pulse light with high dynamic extinction ratio is shown, which proposes to use an acousto-optic modulator 5 with higher extinction ratio to chop the continuous light to generate pulse light, and then amplify the power of the pulse light. The advantage of this solution is that the extinction ratio of the acousto-optic modulator can reach 50dB, thus allowing laser sensing and detection in the near field region and the far field region.

[0005] However, pulse light with a 50dB extinction ratio cannot meet the demand of longer distance detection, so the prior art has made further improvements on the basis of the above-mentioned solution, and proposes to realize a pulse extinction ratio of 100dB by connecting two acousto-optic modulators (as shown in Figure 2 ) or multiplexing an acousto-optic modulator twice (as shown in Figure 3 ), so as to realize laser sensing and detection in the near field region and the far field region.

[0006] For this reason, in the current long-range laser radar detection application, in view of the demand for high extinction ratio, the solution of driving the laser to generate continuous light signal under direct current bias, and then using one or more acousto-optic modulators to chop the continuous light signal to obtain high extinction ratio pulse is generally adopted.

[0007] The above solution of generating continuous light signal by using direct current driven laser and then chopping by one or more acousto-optic modulators can indeed obtain high extinction ratio of more than 100 dB, and realize detection in near field area and further field area. However, it has the following obvious shortcomings, that is, acousto-optic modulators must be used, and acousto-optic modulators are large in size, expensive in price, and need to be matched with high-power drivers, and more importantly, since the bandwidth of acousto-optic modulators is generally about 100 MHz, the pulse width of the pulsed light generated by chopping the continuous light by acousto-optic modulators is about 100 nanoseconds, which leads to poor resolution index, that is, although long-range detection can be realized, the resolution is low.

[0008] However, if long-range and high-resolution detection are to be realized at the same time, laser pulses with narrow pulse width (picosecond level) and high extinction ratio (100 dB or even higher) are needed. Obviously, the solution based on the inherent acousto-optic modulator chopping continuous light of the person skilled in the art cannot meet this demand. Invention content

[0009] In view of the above problems existing in the prior art, the utility model discloses a high dynamic extinction ratio narrow laser pulse generating device, wherein the driver that provides radio frequency signal is configured to drive the laser to directly generate the narrow (picosecond level) laser pulse with higher dynamic extinction ratio (for example, more than 50 dB), and then the combination of conventional electro-optic intensity modulator and reflecting unit is used to modulate the intensity of the narrow laser pulse twice to improve its dynamic extinction ratio, finally, the laser pulse with high dynamic extinction ratio (more than 100 dB) and narrow pulse width (picosecond level) is obtained, so that the demand of long-range detection and high-resolution detection can be met at the same time. Compared with the existing pulse light generating device, the laser pulse generating device of the utility model has the advantages of smaller size, wider bandwidth, lower price and smaller power consumption.

[0010] Specifically, the utility model discloses a high dynamic extinction ratio narrow laser pulse generating device, which comprises a driver, a laser and an optical amplification unit, and further comprises an optical transmission unit, an electro-optic intensity modulator and a reflecting unit.

[0011] The optical transmission unit has a first port, a second port and a third port, wherein the optical signal input through the first port is output by the second port, and the optical signal input through the second port is output by the third port.

[0012] The output port of the laser is optically connected with a first port of an optical transmission unit;

[0013] Two ends of the electro-optical intensity modulator are optically connected with a second port of the optical transmission unit and a reflecting unit respectively;

[0014] The optical amplification unit is optically connected with a third port of the optical transmission unit;

[0015] The driver is arranged to generate a radio frequency driving signal without direct current bias;

[0016] The laser is arranged to generate narrow laser pulses under the driving of the radio frequency driving signal;

[0017] The electro-optical intensity modulator is arranged to intensity modulate the narrow laser pulses;

[0018] The reflecting unit is arranged to make the narrow laser pulses reflect back along the original path.

[0019] Preferably, the optical amplification unit is a fiber amplifier.

[0020] Further, the fiber amplifier comprises a gain fiber and a pump laser.

[0021] Preferably, the gain fiber is doped with rare earth elements.

[0022] Preferably, the electro-optical intensity modulator is a lithium niobate electro-optical intensity modulator.

[0023] Preferably, the optical transmission unit is a circulator.

[0024] Preferably, the reflecting unit is a mirror.

[0025] Preferably, the optical connections between the laser and the optical transmission unit, between the optical transmission unit and the electro-optical intensity modulator, between the electro-optical intensity modulator and the reflecting unit, and between the optical transmission unit and the optical amplification unit are implemented through optical fibers. BRIEF DESCRIPTION OF DRAWINGS

[0026] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these accompanying drawings without any creative effort.

[0028] Figure 1A typical structure of the prior high dynamic extinction ratio pulsed light generating device is shown.

[0029] Figure 2 An improved structure of the prior high dynamic extinction ratio pulsed light generating device is shown.

[0030] Figure 3 Another improved structure of the prior high dynamic extinction ratio pulsed light generating device is shown.

[0031] Figure 4 A preferred example of the high dynamic extinction ratio narrow laser pulse generating device according to the present application is shown. DETAILED DESCRIPTION

[0032] In the following, the exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example in order to fully convey the spirit of the present application to those skilled in the art to which the present application pertains. Therefore, the present application is not limited to the embodiments disclosed herein.

[0033] Figure 4 A high dynamic extinction ratio narrow laser pulse generating device according to the present application is schematically shown, which can generate narrow (picosecond order) laser pulses with high dynamic extinction ratio (greater than 100 dB) to meet the requirements of both long distance detection and high resolution detection.

[0034] As Figure 4 shown, the high dynamic extinction ratio narrow laser pulse generating device includes a driver, a laser, an optical transmission unit, an electro-optical intensity modulator, a reflection unit and an optical amplification unit.

[0035] The optical transmission unit can have a first port, a second port and a third port, wherein the optical signal (e.g. laser pulse) input through the first port will be output by the second port, and the optical signal (e.g. laser pulse) input through the second port will be output by the third port.

[0036] As an example, the optical transmission unit can be a circulator, which has a first port 1, a second port 2 and a third port 3.

[0037] Unlike the prior art, the present application introduces a driver for outputting a radio frequency driving signal without direct current bias, so that under the driving of the radio frequency driving signal provided by the driver, the laser can generate narrow (picosecond order) laser pulses with higher dynamic extinction ratio (more than 50 dB).

[0038] The output port of the laser and the first port of the optical transmission unit form optical connection, the two ends of the electro-optical intensity modulator form optical connection with the second port of the optical transmission unit and the reflecting unit respectively, and the optical amplification unit forms optical connection with the third port of the optical transmission unit.

[0039] As an example, the laser and the optical transmission unit, the optical transmission unit and the electro-optical intensity modulator, the electro-optical intensity modulator and the reflecting unit, and the optical transmission unit and the optical amplification unit can be connected through optical fibers to realize the corresponding optical connection relationship.

[0040] In the utility model, the electro-optical intensity modulator adopts conventional electro-optical intensity modulator, and it usually has lower dynamic extinction ratio (usually 25dB-30dB), wide bandwidth (more than 10GHz) and small half-wave voltage (less than 5V).

[0041] As an example, the electro-optical intensity modulator can be lithium niobate electro-optical intensity modulator.

[0042] In the utility model, the reflecting unit can be in the form of a mirror.

[0043] In the utility model, the optical amplification unit can be in the form of a fiber amplifier.

[0044] As an example, the fiber amplifier can include gain optical fiber doped with rare earth elements (such as erbium ions, ytterbium ions, thulium ions, etc.) and pump laser.

[0045] Continuing to refer to Figure 4 In the high dynamic extinction ratio narrow laser pulse generating device of the utility model, the laser will first directly output narrow laser pulse under the driving of (radio frequency signal) driver, the narrow laser pulse passes through the first port and the second port of the optical transmission unit in turn, and passes through the electro-optical intensity modulator for the first time to allow the first intensity modulation of the narrow laser pulse by the electro-optical intensity modulator, thereby preliminarily improving the dynamic extinction ratio thereof; the narrow laser signal output from the electro-optical intensity modulator will return along the original path and pass through the electro-optical intensity modulator again after the reflecting action of the reflecting unit, so that the same electro-optical intensity modulator can be used for intensity modulation of the narrow laser pulse again, thereby improving the dynamic extinction ratio again. By using the same electro-optical intensity modulator to modulate the same narrow laser pulse twice, the above-mentioned high dynamic extinction ratio can be realized on the narrow laser pulse by using a single conventional electro-optical intensity modulator, and finally the narrow laser pulse with high dynamic extinction ratio is obtained.

[0046] In summary, the utility model discloses a specific drive is configured to drive laser to directly generate narrow laser pulse with high dynamic extinction ratio, and at the same time, the same (conventional) electro-optic intensity modulator is used to process the narrow laser pulse twice, so as to generate high dynamic extinction ratio narrow laser pulse, thereby meeting the requirements of long-distance detection and high-resolution detection at the same time.Compared with the pulse light generating device in the prior art, which is realized by means of continuous light laser and acousto-optic modulator, the acousto-optic modulator with large power consumption, large size and high cost is no longer needed, and the narrow pulse laser and the electro-optic intensity modulator with worse single-stage extinction ratio index can be used to generate high dynamic extinction ratio narrow laser pulse, which has smaller power consumption, smaller size and lower cost.At the same time, the generated laser pulse has narrow (picosecond order) pulse width, which is nearly ten thousand times narrower than the pulse light generated by the existing device, so as to effectively guarantee the laser radar to realize long-distance and high-resolution detection at the same time.

[0047] Although the utility model has been described in the foregoing by specific embodiments combined with the drawings, those skilled in the art can easily recognize that the above-mentioned embodiments are only exemplary, used for explaining the principle of the utility model, and will not limit the scope of the utility model, and various combinations, modifications and equivalent replacements can be made to the above-mentioned embodiments without departing from the spirit and scope of the utility model.

Claims

1. A high dynamic extinction ratio narrow laser pulse generation device, comprising a driver, a laser, and an optical amplification unit, characterized in that it further comprises an optical transmission unit, an electro-optic intensity modulator, and a reflection unit; The optical transmission unit has a first port, a second port, and a third port, wherein, The optical signal input through the first port is output through the second port, and the optical signal input through the second port is output through the third port. The output port of the laser is optically connected to the first port of the optical transmission unit; The two ends of the electro-optic intensity modulator are optically connected to the second port of the optical transmission unit and the reflection unit, respectively. The optical amplification unit and the third port of the optical transmission unit form an optical connection; The driver is configured to generate a radio frequency drive signal without DC bias. The laser is configured to generate narrow laser pulses under the drive of a radio frequency drive signal; The electro-optic intensity modulator is configured to intensity modulate narrow laser pulses; The reflection unit is configured to reflect narrow laser pulses back along their original path.

2. The high dynamic extinction ratio narrow laser pulse generation device as described in claim 1, characterized in that, The optical amplification unit is an optical fiber amplifier.

3. The high dynamic extinction ratio narrow laser pulse generation device as described in claim 2, characterized in that, The fiber amplifier includes a gain fiber and a pump laser.

4. The high dynamic extinction ratio narrow laser pulse generation device as described in claim 3, characterized in that, The gain fiber is doped with rare earth elements.

5. The high dynamic extinction ratio narrow laser pulse generation device as described in claim 1, characterized in that, The electro-optic intensity modulator is a lithium niobate electro-optic intensity modulator.

6. The high dynamic extinction ratio narrow laser pulse generation device as described in claim 1, characterized in that, The optical transmission unit is a circulator.

7. The high dynamic extinction ratio narrow laser pulse generation device as described in claim 1, characterized in that, The reflecting unit is a reflector.

8. The high dynamic extinction ratio narrow laser pulse generating device as described in any one of claims 1-7, characterized in that, The laser and the optical transmission unit, the optical transmission unit and the electro-optic intensity modulator, the electro-optic intensity modulator and the reflection unit, and the optical transmission unit and the optical amplification unit are optically connected by optical fibers.

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