CN202533676U - Optical fiber acousto-optic frequency shifter - Google Patents
Optical fiber acousto-optic frequency shifter Download PDFInfo
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- CN202533676U CN202533676U CN 201220231261 CN201220231261U CN202533676U CN 202533676 U CN202533676 U CN 202533676U CN 201220231261 CN201220231261 CN 201220231261 CN 201220231261 U CN201220231261 U CN 201220231261U CN 202533676 U CN202533676 U CN 202533676U
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- acousto
- optic
- frequency
- optical fiber
- shift
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Abstract
An optical fiber acousto-optic frequency shifter is equipped with two closely-arranged acousto-optic crystals which form an angle Theta, wherein Theta=Lambada(f1+f2)/2V; the f1 and the f2 are the carrier frequency of the first acousto-optic crystal and the second acousto-optic crystal; the Lambada is a laser wavelength; the V is the speed of sound transmitted in the crystals; an incident light firstly passes through the first acousto-optic crystal at the Bragg angle and diffracts for the first time; a transmitted diffraction light radiates into the second acousto-optic crystal and diffracts secondly; by respectively utilizing a mutual counteraction effect of the positive frequency shift and the negative frequency shift of the acousto-optic crystals, the frequency shift of the diffracted light is small or no frequency shift is generated; a separation angle between an emergent light and the incident light is very large; an extinction ratio is more than 50dB; and a strict separation condition can be completely met. By controlling the carrier frequency of the two acousto-optic crystals, the shift frequency can be within a range of zero to dozens of MHz, the function of an acousto-optic device can cover a low-frequency band, and application range is enlarged.
Description
Technical field
The utility model relates to acousto-optical device, especially a kind ofly can directly be applied in optical fiber acousto-optic frequency shifters in the optical fiber sensing system.
Background technology
The optical fiber acousto-optic frequency shifters is utilized the ultimate principle of acousto-optic Bragg diffraction; When incident light through behind the acousto-optic crsytal diffraction takes place with Prague angle; Have a vector matching relations between diffraction light and incident light and the acoustic vector three, the diffraction light frequency is the stack of incident light frequency and acoustic vector frequency.Because diffraction light exists+1 order diffraction and two kinds of situation of-1 order diffraction, so the frequency shift function of optical fiber acousto-optic frequency shifters exists positive shift frequency (also deserving to be called shift frequency) and two kinds of situation of negative shift frequency (also claiming shift frequency down).
Existing acousto-optical device extinction ratio numerical value is little, can not satisfy the strict separation condition of signal fully, and the signal to noise ratio (S/N ratio) of signal is little.And the shift frequency frequency of existing acousto-optical device is all more than 30MHz, and existence can not cover the situation of low-frequency range.
Summary of the invention
To the problems referred to above, the utility model provides a kind of optical fiber acousto-optic frequency shifters that can cover low-frequency range shift frequency frequency.
To achieve these goals, the technical scheme of the utility model employing is following:
A kind of optical fiber acousto-optic frequency shifters; The bag body is characterized in that said body is provided with first radio-frequency joint and second radio-frequency joint; Said first radio-frequency joint is connected with the input end that is installed in intrinsic first matching network; The output terminal of this first matching network is connected with first acousto-optic crsytal, and said second radio-frequency joint is connected with the input end that is installed in intrinsic second matching network, and the output terminal of this second matching network is connected with second sound luminescent crystal; The adjacent acousto-optic crsytal parts that constitute frequency shifter that are provided with of these two acousto-optic crsytals; The both sides of acousto-optic crsytal parts are respectively arranged with an optical fiber, and the front end of these two optical fiber all is equipped with optical fiber collimator, and the rear end of optical fiber all passes said body;
Said first acousto-optic crsytal and second sound luminescent crystal are positioned at same plane; This acousto-optic crsytal input end is in the opposite direction; And these two acousto-optic crsytals have angle
; Wherein
;
and
is respectively the carrier frequency of first acousto-optic crsytal and second sound luminescent crystal; λ is an optical maser wavelength, and V is the velocity of propagation of sound in crystal.
The good effect of the utility model:
First acousto-optic crsytal and second sound luminescent crystal are placed at a certain angle; Utilize the positive shift frequency and the effect of cancelling out each other of negative shift frequency of acousto-optic crsytal respectively; Make the diffraction light frequency displacement very little or do not produce any frequency displacement; The angle of departure is very big between emergent light and the incident light, and extinction ratio can reach more than the 50dB, can satisfy the strict separation condition of signal fully.
Through controlling the carrier frequency of two blocks of acousto-optic crsytals; When the carrier frequency of first acousto-optic crsytal and second sound luminescent crystal is identical; The shift frequency frequency reaches 0; Thereby realized making the shift frequency frequency between 0 to tens megahertz, made the acousto-optical device frequency shift function can cover the low frequency section, enlarged usable range.
Description of drawings
Fig. 1 is the structural representation of the utility model;
Fig. 2 is that the position of acousto-optic crsytal concerns synoptic diagram.
Embodiment
Below in conjunction with specific embodiment the utility model is done further explain.
As shown in Figure 1; A kind of optical fiber acousto-optic frequency shifters, bag body 1, this body 1 is provided with first radio-frequency joint 2 and second radio-frequency joint 3; Said first radio-frequency joint 2 is connected with the input end of first matching network 4 in being installed in body 1; The output terminal of this first matching network 4 is connected with first acousto-optic crsytal 6, and said second radio-frequency joint 3 is connected with the input end of second matching network 5 in being installed in body 1, and the output terminal of this second matching network 5 is connected with second sound luminescent crystal 7; The adjacent acousto-optic crsytal parts that constitute frequency shifter that are provided with of these two acousto-optic crsytals; The both sides of acousto-optic crsytal parts are respectively arranged with an optical fiber, and the front end of these two optical fiber all is equipped with optical fiber collimator, and the rear end of optical fiber all passes said body 1;
As shown in Figure 2; First acousto-optic crsytal 6 is positioned at same plane with second sound luminescent crystal 7; This acousto-optic crsytal input end is in the opposite direction; And these two acousto-optic crsytals have angle
; Wherein
;
and
is respectively the carrier frequency of first acousto-optic crsytal 6 and second sound luminescent crystal 7; λ is an optical maser wavelength, and V is the velocity of propagation of sound in acousto-optic crsytal.
Adjust first optical fiber collimator 8 and second optical fiber collimator, 9 angles; Laser gets into first acousto-optic crsytal 6 through input optical fibre 10 with Bragg angle during use; Diffraction takes place in laser in first acousto-optic crsytal 6; Diffraction takes place through second sound luminescent crystal 7 in diffraction light once more, and last secondary diffraction light is through second optical fiber collimator 9 and output optical fibre 11 outputs.
It is identical with the carrier frequency of second sound luminescent crystal 7 to control first acousto-optic crsytal 6 during use.Utilize the positive shift frequency and the negative shift frequency of two acousto-optic crsytals respectively, offset the frequency displacement that diffraction light produces, make diffraction light not produce any frequency displacement; Apply the switch modulation signal simultaneously for two acousto-optic crsytals,, can realize not having the frequency displacement light switch function through the certain delay synchronous processing; Can directly be applied in the optical fiber sensing system; Like laser windfinding radar, fibre optic hydrophone etc., under the situation that does not change optical frequency, make extinction ratio improve several more than magnitude, increase substantially the signal to noise ratio (S/N ratio) of signal.
The shift frequency frequency of traditional acousto-optic frequency shifters is all more than 30MHz; Utilize the utility model; The frequency shift function that can fundamentally change acousto-optical device can not cover the situation of low side; Through controlling the carrier frequency of two crystal, when the carrier frequency of first acousto-optic crsytal 6 and second sound luminescent crystal 7 was identical, the shift frequency frequency was 0.The carrier frequency of first acousto-optic crsytal 6 and second sound luminescent crystal 7 also can be different, can realize making shift frequency frequency from 0 to tens MHz changing, and enlarged the usable range of product.
The foregoing description of the utility model only is to give an example for what explanation the utility model was done, and is not to be the qualification to the embodiment of the utility model.For the those of ordinary skill in affiliated field, on the basis of above-mentioned explanation, can also make other multi-form variation and changes.Here can't give exhaustive to all embodiments.Conspicuous variation that every technical scheme that belongs to the utility model is amplified out or change still are in the row of the protection domain of the utility model.
Claims (1)
1. optical fiber acousto-optic frequency shifters; Bag body (1); It is characterized in that; Said body (1) is provided with first radio-frequency joint (2) and second radio-frequency joint (3), and the input end of first matching network (4) that said first radio-frequency joint (2) is interior with being installed in body (1) is connected, and the output terminal of this first matching network (4) is connected with first acousto-optic crsytal (6); The input end of second matching network (5) that said second radio-frequency joint (3) is interior with being installed in body (1) is connected; The output terminal of this second matching network (5) is connected with second sound luminescent crystal (7), the adjacent acousto-optic crsytal parts that constitute frequency shifter that are provided with of these two acousto-optic crsytals, and the both sides of acousto-optic crsytal parts are respectively arranged with an optical fiber; The front end of these two optical fiber all is equipped with optical fiber collimator, and the rear end of optical fiber all passes said body (1);
Said first acousto-optic crsytal (6) and second sound luminescent crystal (7) are positioned at same plane; This acousto-optic crsytal input end is in the opposite direction; And these two acousto-optic crsytals have angle
; Wherein
;
and
is respectively the carrier frequency of first acousto-optic crsytal (6) and second sound luminescent crystal (7); λ is an optical maser wavelength, and V is the velocity of propagation of sound in crystal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220231261 CN202533676U (en) | 2012-05-22 | 2012-05-22 | Optical fiber acousto-optic frequency shifter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220231261 CN202533676U (en) | 2012-05-22 | 2012-05-22 | Optical fiber acousto-optic frequency shifter |
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| CN202533676U true CN202533676U (en) | 2012-11-14 |
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| CN 201220231261 Expired - Lifetime CN202533676U (en) | 2012-05-22 | 2012-05-22 | Optical fiber acousto-optic frequency shifter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102662255A (en) * | 2012-05-22 | 2012-09-12 | 中国电子科技集团公司第二十六研究所 | Optical fiber acousto-optic frequency shift method and device |
| CN103076654A (en) * | 2013-03-04 | 2013-05-01 | 中国电子科技集团公司第二十六研究所 | Polarization maintaining optical fiber acousto-optic frequency shift device |
-
2012
- 2012-05-22 CN CN 201220231261 patent/CN202533676U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102662255A (en) * | 2012-05-22 | 2012-09-12 | 中国电子科技集团公司第二十六研究所 | Optical fiber acousto-optic frequency shift method and device |
| CN102662255B (en) * | 2012-05-22 | 2014-11-12 | 中国电子科技集团公司第二十六研究所 | Optical fiber acousto-optic frequency shift method and device |
| CN103076654A (en) * | 2013-03-04 | 2013-05-01 | 中国电子科技集团公司第二十六研究所 | Polarization maintaining optical fiber acousto-optic frequency shift device |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20121114 |