CN210005814U - electro-optic phase modulator with low residual amplitude modulation - Google Patents
electro-optic phase modulator with low residual amplitude modulation Download PDFInfo
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- CN210005814U CN210005814U CN201920675611.4U CN201920675611U CN210005814U CN 210005814 U CN210005814 U CN 210005814U CN 201920675611 U CN201920675611 U CN 201920675611U CN 210005814 U CN210005814 U CN 210005814U
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- 239000013078 crystal Substances 0.000 claims abstract description 102
- PCTMTFRHKVHKIS-BMFZQQSSSA-N (1s,3r,4e,6e,8e,10e,12e,14e,16e,18s,19r,20r,21s,25r,27r,30r,31r,33s,35r,37s,38r)-3-[(2r,3s,4s,5s,6r)-4-amino-3,5-dihydroxy-6-methyloxan-2-yl]oxy-19,25,27,30,31,33,35,37-octahydroxy-18,20,21-trimethyl-23-oxo-22,39-dioxabicyclo[33.3.1]nonatriaconta-4,6,8,10 Chemical compound C1C=C2C[C@@H](OS(O)(=O)=O)CC[C@]2(C)[C@@H]2[C@@H]1[C@@H]1CC[C@H]([C@H](C)CCCC(C)C)[C@@]1(C)CC2.O[C@H]1[C@@H](N)[C@H](O)[C@@H](C)O[C@H]1O[C@H]1/C=C/C=C/C=C/C=C/C=C/C=C/C=C/[C@H](C)[C@@H](O)[C@@H](C)[C@H](C)OC(=O)C[C@H](O)C[C@H](O)CC[C@@H](O)[C@H](O)C[C@H](O)C[C@](O)(C[C@H](O)[C@H]2C(O)=O)O[C@H]2C1 PCTMTFRHKVHKIS-BMFZQQSSSA-N 0.000 claims description 35
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 10
- 239000000853 adhesive Substances 0.000 claims description 7
- 230000001070 adhesive effect Effects 0.000 claims description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052737 gold Inorganic materials 0.000 claims description 4
- 239000010931 gold Substances 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 238000002310 reflectometry Methods 0.000 claims description 4
- 230000000295 complement effect Effects 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 239000010949 copper Substances 0.000 claims description 3
- WYOHGPUPVHHUGO-UHFFFAOYSA-K potassium;oxygen(2-);titanium(4+);phosphate Chemical compound [O-2].[K+].[Ti+4].[O-]P([O-])([O-])=O WYOHGPUPVHHUGO-UHFFFAOYSA-K 0.000 claims description 3
- 230000003746 surface roughness Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 5
- 235000009537 plain noodles Nutrition 0.000 abstract 2
- 238000010276 construction Methods 0.000 abstract 1
- 230000005684 electric field Effects 0.000 description 10
- 238000010586 diagram Methods 0.000 description 6
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- 238000001675 atomic spectrum Methods 0.000 description 2
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- 239000008358 core component Substances 0.000 description 1
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- 238000012545 processing Methods 0.000 description 1
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- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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Abstract
In order to solve the present scheme that reduces surplus amplitude modulation, can only weaken surplus amplitude modulation effect to degree, and complex operation is time-consuming, increased the degree of difficulty that the light path was adjusted and was arranged, to the electro-optic crystal place the required precision higher, be unfavorable for the miniaturized technical problem of device, the utility model provides a kind low surplus amplitude modulation's electro-optic phase modulator, the utility model discloses a design special construction's electro-optic crystal to the logical plain noodles of messenger's electro-optic crystal is corresponding with the position of logical unthreaded hole on the casing, avoided the back and forth reflection of light beam between two logical plain noodles, effectively reduced surplus amplitude modulation, and then improved phase modulation's accuracy.
Description
Technical Field
The utility model relates to a laser control technical field especially relates to low surplus amplitude modulation's electro-optic phase modulator.
Background
The electro-optical phase modulation technology has high sensitivity, so the electro-optical phase modulation technology is widely applied to the technical fields of atomic precision spectroscopy, laser frequency locking and the like, at present, generally realizes the electro-optical phase modulation through an electro-optical phase modulator, and the core component of the electro-optical phase modulator is an electro-optical crystal.
At present, electro-optic phase modulation is divided into transverse electro-optic phase modulation and longitudinal electro-optic phase modulation, in the transverse electro-optic modulation, the direction of an electric field is required to be vertical to the direction of a light beam in an electro-optic crystal, is realized by sending radio frequency signals on two opposite surfaces provided with electrodes of the cuboid electro-optic crystal through a radio frequency circuit, so that an electric field with the direction vertical to the two surfaces is formed between the two surfaces, the light beam vertically enters the electro-optic crystal from light-passing surfaces (incident light-passing surfaces) and enters the electro-optic crystal, and the direction of the light beam entering the electro-optic crystal is vertical to the direction of the electric field.
In the prior art, in order to reduce the residual amplitude modulation, antireflection films are plated on the incident light-passing surface and the exit light-passing surface of the electro-optic crystal, and the antireflection film reduces the back-and-forth reflection of the light beam between the two light-passing surfaces, but the antireflection film cannot completely avoid the back-and-forth reflection of the light beam between the two light-passing surfaces, and weak residual light beam energy still exists and is reflected back-and-forth between the two light-passing surfaces, so compared with the case of no film plating, the method can weaken the residual amplitude modulation effect, but the influence of the residual amplitude modulation effect on a precise atomic spectrum test is still obvious.
In addition, schemes are shown in fig. 1, the incident light-passing surface and the exit light-passing surface of the electro-optical crystal, the upper electrode surface and the lower electrode surface are all cut into brewster angle θ, and the incident light surface and the exit light surface are parallel, which effectively reduces the back-and-forth reflection of the light beam between the two light-passing surfaces, and greatly inhibits the residual amplitude modulation effect, thereby significantly improving the accuracy of phase modulation.
SUMMERY OF THE UTILITY MODEL
In order to solve the present scheme that reduces surplus amplitude modulation, can only weaken surplus amplitude modulation effect to degree to and complex operation time-consuming, increased the degree of difficulty that the light path was adjusted and was arranged, to placing the technical problem that the required precision is higher, be unfavorable for the device miniaturization of electro-optical crystal, the utility model provides a low surplus amplitude modulation's electro-optical phase modulator.
The technical solution of the utility model is as follows:
electro-optic phase modulator with low residual amplitude modulation, which comprises a shell, an electro-optic crystal and a radio frequency circuit, wherein the electro-optic crystal and the radio frequency circuit are arranged in the shell, the electro-optic crystal comprises an upper electrode surface ABCD, a lower electrode surface A 'B' C 'D', a light passing surface ACA 'C', a second light passing surface DBD 'B', a light reflecting surface ABA 'B' and a second light reflecting surface CDC 'D', A, B, D, C is respectively a sequential mark of four vertexes of the upper electrode surface, and A ', B', D 'and C' are respectively a sequential mark of four vertexes of the lower electrode surface;
the th light through hole and the second light through hole are respectively arranged on two opposite side walls of the shell, and the radio frequency signal adapter is also arranged on the side walls of the shell;
two signal input electrodes of the radio frequency circuit are respectively connected with two electrodes of the radio frequency signal adapter, and two signal output electrodes of the radio frequency circuit are respectively connected with an upper electrode surface ABCD and a lower electrode surface A 'B' C 'D' of the electro-optical crystal;
it is characterized in that:
the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D' are congruent trapezoids and are parallel to each other; the parts, opposite to the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D', are plated with conductive films;
the light passing surface ACA 'C' and the second light passing surface DBD 'B' are both positioned between the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D' and are symmetrical about the centerline of the upper electrode surface ABCD;
the th reflecting surface ABA 'B' and the second reflecting surface CDC 'D' are parallel and are both vertical to the upper electrode surface ABCD, and the th reflecting surface ABA 'B' and the second reflecting surface CDC 'D' are both plated with medium total reflection films for the light wavelength passed by the electro-optical crystal;
an included angle between the th light reflecting surface ABA 'B' and the th light passing surface ACA 'C' and an included angle between the th light reflecting surface ABA 'B' and the second light passing surface DBD 'B' are complementary angles of Brewster angles;
the optical axis direction of the electro-optical crystal is the direction from the th light reflecting surface ABA 'B' to the second light reflecting surface CDC 'D';
the length of the long side of the th light reflecting surface ABA 'B' is calculated according to the formula
Determining, wherein n is the refractive index of the electro-optical crystal to the ordinary ray, h is the distance between th reflecting surface ABA 'B' and the second reflecting surface CDC 'D', and j is the reflection times of the light beam on the second reflecting surface CDC 'D';
the central axes of the light-passing hole and the second light-passing hole are parallel to the reflecting surface ABA 'B' and the second reflecting surface CDC 'D', and pass through the geometric centers of the light-passing surface ACA 'C' and the second light-passing surface DBD 'B'.
And , the angle error between two adjacent planes of the electro-optical crystal is not more than 2 angular minutes.
And , the parallelism between the two parallel surfaces of the electro-optic crystal is not more than 2-angle.
, the light passing surfaces ACA 'C', the second light passing surfaces DBD 'B', the light reflecting surfaces ABA 'B' and the second light reflecting surfaces CDC 'D' have surface roughness better than 0.008 microns.
, the reflectivity of light reflecting surface ABA 'B' and the reflectivity of the second light reflecting surface CDC 'D' after coating are not lower than 99.7 percent.
Further , the conductive film is a gold film.
, the shell is made of copper material.
Step , the distance between the upper electrode plane ABCD and the lower electrode plane A 'B' C 'D' is greater than the diameter of the incident beam.
, the electro-optical crystal is lithium niobate crystal, magnesium-doped lithium niobate crystal or potassium titanyl phosphate crystal.
, a conductive adhesive is arranged on the lower electrode surface A 'B' C 'D', and the electro-optic crystal is fixed in the shell through the conductive adhesive.
The utility model has the advantages that:
1) the back-and-forth reflection of the light beam between the two light-passing surfaces is avoided, the residual amplitude modulation is effectively reduced, and the accuracy of phase modulation is further improved.
2) And the spatial positions of the incident beam and the emergent beam do not have transverse deviation, so that the difficulty of light path arrangement is reduced.
3) Under the condition that the length of the electro-optical crystal is the same, the transmission distance of the light beam in the electro-optical crystal is longer, and further the effective length of electro-optical modulation is longer, so that the length and the transverse size of the electro-optical phase modulator can be obviously reduced, and the miniaturization of devices is facilitated.
4) The alignment condition of light beam incidence is low, the operation is convenient, the light beam is incident from the light through hole at the end of the electro-optical phase modulator housing and is vertical to the plane where the light through hole is located, so that the light beam can be ensured to be emitted from the light through hole at the other end , and the light beam is parallel to the non-light-through side face of the housing.
Drawings
Fig. 1 is a schematic structural diagram of an electro-optic phase modulator with a light-passing surface and an electrode surface at brewster angle θ in the prior art, the electro-optic phase modulator is shown in a plan view, and radio frequency circuits and the like are not shown.
Fig. 2 is a schematic structural diagram of the electro-optic phase modulator of the present invention.
Fig. 3 is a schematic bottom structure diagram of the electro-optic phase modulator provided by the present invention.
Fig. 4 is a schematic diagram of an electro-optic crystal structure provided by the present invention.
Fig. 5 is a schematic diagram illustrating the transmission process of the laser beam in the electro-optic crystal of the present invention.
Fig. 6 is a schematic diagram of a transmission process of the laser beam in the electro-optical crystal of the present invention.
Description of reference numerals:
400-electro-optic crystal, 500-encapsulating housing;
100-shell, 101-second light through hole, 102- th light through hole, 103-radio frequency signal adapter, 104-cover plate, 105, 106, 107 and 108-mounting screw hole of electro-optical phase modulator, 200-electro-optical crystal, 300-radio frequency circuit, 301 and 302-copper wire.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 2, the electro-optic phase modulator with low residual amplitude modulation provided by the present invention includes an electro-optic crystal 200, a housing 100, and a radio frequency circuit 300;
the shell 100 is a hollow cuboid, the bottom of the shell is closed, the top of the shell is opened, the top of the shell is closed by a cover plate 104, and the shell 100 is made of copper materials; both the electro-optic crystal 200 and the radio frequency circuit 300 are disposed within the housing 100.
As shown in fig. 4, the electro-optical crystal 200 includes an upper electrode surface ABCD, a lower electrode surface a 'B' C 'D', an th light passing surface ACA 'C', a second light passing surface DBD 'B', a th light reflecting surface ABA 'B', and a second light reflecting surface CDC 'D';
the upper electrode face ABCD and the lower electrode face A 'B' C 'D' are congruent trapezoids, are parallel to each other, and the distance between the upper electrode face ABCD and the lower electrode face A 'B' C 'D' is larger than the diameter of an incident beam. The opposite parts of the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D' are plated with conductive films, and the lower electrode surface A 'B' C 'D' is provided with conductive adhesive for fixing the electro-optical crystal 200 on the inner bottom surface of the shell 100;
the light passing surface ACA 'C' and the second light passing surface DBD 'B' are both positioned between the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D' and are symmetrical about the centerline of the upper electrode surface ABCD;
the th reflecting surface ABA 'B' and the second reflecting surface CDC 'D' are parallel and are both vertical to the upper electrode surface ABCD, and the th reflecting surface ABA 'B' and the second reflecting surface CDC 'D' are both plated with a medium total reflection film for the light wavelength passed by the electro-optical crystal 200;
the included angles β and gamma between the th light reflecting surface ABA 'B' and the th light passing surface ACA 'C' and the th light reflecting surface ABA 'B' and the th light passing surface DBD 'B' are complementary angles of the Brewster angle theta, the Brewster angle is related to the wavelength of the light beam and the property (such as the refractive index) of the electro-optical crystal 200, and the Brewster angle is fixed angles when the wavelength of the light beam is fixed and the material of the electro-optical crystal 200 is fixed.
The Z direction is defined as a direction from the th light reflecting surface ABA 'B' to the second light reflecting surface CDC 'D', and the optical axis direction of the electro-optical crystal 200 is the Z direction.
The geometrical parameters of the electro-optic crystal 200 are chosen in the following relationship:
the length of the side AB of the electro-optical crystal 200 is calculated according to the formula
It is determined that where n is a refractive index of the electro-optical crystal 200 for ordinary light (O light), h is a distance between the th light reflecting surface ABA 'B' and the second light reflecting surface CDC 'D', and j is a number of times of reflection of the light beam at the second light reflecting surface CDC 'D' (j is 0, 1, 2 …), in the birefringence phenomenon, light that follows the ordinary law of refraction is called ordinary light (O light) whose polarization direction is perpendicular to the principal plane of the ordinary light, and light that does not follow the ordinary law of refraction is called extraordinary light (e light) whose polarization direction is within the principal plane of the extraordinary light.
In this embodiment, the light beam is a laser beam, the electro-optical crystal 200 can be kinds of lithium niobate crystals, magnesium-doped lithium niobate crystals and potassium titanyl phosphate crystals, certainly in the practical application process, the electro-optical crystal 200 can also be made of other materials, the utility model discloses do not limit specifically to this, steps are advanced, in order to guarantee the accuracy of the electro-optical phase modulator, the processing parameters of the electro-optical crystal 200 can be as follows, the angle error between two adjacent surfaces is not more than 2 angular points, the parallelism between two parallel surfaces is not more than 2 angular points, the surface roughness of the light transmitting surface and the light reflecting surface is superior to 0.008 micrometer (PV value), the reflectivity of the light reflecting surface after being coated is not less than 99.7%, and the conductive film coated on the electrode surface is a gold film.
The electro-optical crystal 200 is fixed in the housing 100 through the conductive adhesive on the lower electrode surface A 'B' C 'D', the geometric long axis of the electro-optical crystal 200 is parallel to the geometric long axis of the housing 100, the two opposite side walls of the housing 100 are respectively provided with a th light through hole 102 and a second light through hole 101, the th light through hole 102 corresponds to the th light through surface ACA 'C' position of the electro-optical crystal 200, the second light through hole 101 corresponds to the second light through surface DBD 'B' position of the electro-optical crystal 200, the central axes of the th light through hole 102 and the second light through hole 101 are parallel to the th light reflecting surface ABA 'B' and the second light reflecting surface CDC 'D' of the electro-optical crystal 200 and pass through the geometric centers of the th light through surface ACA 'C' and the second light through surface DBD 'B' (namely, the geometric centers of the two light through surfaces of the electro-optical crystal 200 are coincident with the geometric center connecting.
The light beams can be incident from any light-passing surfaces of the electro-optical crystal 200, the included angle between the light beams and the light-incident light-passing surfaces is the brewster angle, and the incident light beams are parallel to the two light-reflecting surfaces of the electro-optical crystal 200, which is as follows:
the light beam enters from the th light passing hole 102 of the shell 100 to the th light passing surface ACA 'C' of the electro-optical crystal 200, is reflected for multiple times between the th light reflecting surface ABA 'B' and the second light reflecting surface CDC 'D' of the electro-optical crystal 200, reaches the second light passing surface DBD 'B' of the electro-optical crystal 200, passes through the second light passing surface DBD 'B' and then exits from the second light passing hole 101 of the shell 100, and the included angles between the light beam and the th light passing surface ACA 'C' and the second light passing surface DBD 'B' are Brewster angles.
Or, the light beam enters the second light passing surface DBD 'B' of the electro-optical crystal 200 from the second light passing hole 101 of the housing 100, and after multiple reflections between the th light reflecting surface ABA 'B' and the second light reflecting surface CDC 'D' of the electro-optical crystal 200, the light beam reaches the th light passing surface ACA 'C' of the electro-optical crystal 200, passes through the th light passing surface ACA 'C' and then exits from the th light passing hole 102 of the housing 100, and the included angles between the light beam and the th light passing surface ACA 'C' and the second light passing surface DBD 'B' are both brewster angles.
The radio frequency circuit 300 is fixedly arranged at the mounting screw holes 105-108 at the bottom of the shell 100 through screws, as shown in FIG. 3; a radio frequency signal adapter 103 is arranged on the side wall of the shell 100; the positive electrode of the signal input of the radio frequency circuit 300 is connected with the positive electrode of the radio frequency signal adapter 103 on the casing 100 through a copper wire 301, the negative electrode of the radio frequency signal adapter 103 is conducted with the casing 100 and is used for guiding a radio frequency signal generated by an external signal source into the radio frequency circuit 300, the positive electrode of the signal output of the radio frequency circuit 300 is connected with the upper electrode surface ABCD of the electro-optical crystal 200 through a copper wire 302, and the lower electrode surface A 'B' C 'D' of the electro-optical crystal 200 is bonded with the casing 100 through a conductive adhesive to serve as the negative electrode and is used for sending the radio frequency signal to the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D' so as to form an electric field with an electric field direction vertical to the upper electrode surface and an electric field of the lower electrode surface between the upper.
The electro-optic phase modulator of the present embodiment is further illustrated at step in conjunction with fig. 5, and for convenience of description, the electro-optic crystal 200 is shown in a plan view in fig. 5.
When the rf circuit 300 is powered on, an electric field with an electric field direction perpendicular to the upper electrode face ABCD is formed between the upper electrode face ABCD and the lower electrode face a 'B' C 'D' of the electro-optic crystal 200.
The incident light beam B1 is linearly polarized, the polarization direction is parallel to the incident plane, that is, the incident light beam B1 is P-polarized (P-polarized indicates that the polarization direction of light is in the plane defined by the incident light and the reflected light, otherwise, S-polarized if the polarization direction is perpendicular to the plane), parallel to the optical axis direction (z direction in fig. 4) of the electro-optical crystal 200, and the incident direction is parallel to edge AB of the electro-optical crystal 200, and the incident position is the geometric center of the second light-passing surface ACA ' C ', then the normal angle between the incident light beam B1 and the second light-passing surface ACA ' C ' is brewster angle θ, the incident light beam B1 is refracted after entering the electro-optical crystal 200 to obtain a refracted light beam B2, the refracted light beam B2 is reflected by the second light-reflecting surface ABA ' B ' to reach the second light-reflecting surface CDC ' D ', then is reflected multiple times between the two light-passing surfaces DBD ' B ', and then the emergent light beam B3 is obtained, and the symmetry of the light path 3 and the electro-optical crystal is the geometric center of the second light-passing surface DBD ', and the emergent light path is the second;
the transmission direction of the refracted light beam B2 is parallel to the upper electrode surface ABCD, so that the transmission direction of the refracted light beam B2 is perpendicular to the direction of an electric field between the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D', and the transverse electro-optical modulation condition is met.
Most of the refracted light beam B2 exits from the second light-passing surface DBD 'B' to form an emergent light beam B3, the emergent light beam B3 is parallel to the incident light beam B1, and the geometrical relationship is that: the incident light beam B1 has no lateral deviation of spatial position from the emergent light beam B3, and a small part of refracted light beam B2 is reflected on the second light-passing surface DBD 'B' to form a reflected light beam B4;
since the refracted light beam B2 is emitted from the electro-optic crystal 200 to the outside of the crystal and is transmitted from the optically dense medium to the optically sparse medium, the angle between the refracted light beam B2 and the normal of the second light-passing surface DBD 'B' is smaller than the brewster angle θ, which is not a right angle and is equal to the angle between the reflected light beam B4 and the normal of the second light-passing surface DBD 'B', and therefore, the reflected light beam B4 is not returned by the original path to reach the incident position where the light beam is incident into the electro-optic crystal 200 again, and the light beam is prevented from being reflected back and forth between the light incident surface and the light emergent surface, and the residual amplitude modulation is.
In the above process, if the polarization direction of the incident light beam P1 is not parallel to the upper electrode plane ABCD due to insufficient precision adjustment and small deflection angles exist, the incident light beam P1 is not pure P polarized light with respect to the electro-optic crystal 200, and the incident light beam is incident at the brewster angle, so that the light is reflected at the incident position, and a small part of the incident light beam is reflected and most of the incident light is refracted;
since the emergent light beam S3 is not parallel to the emergent light beam P3, the emergent light beam S3 is blocked by the casing 100 and can not enter the detector, so that the influence of the unwanted polarized light on the wanted polarized light is effectively inhibited, and the residual amplitude modulation caused by the birefringence of the electro-optic crystal is also inhibited; meanwhile, linearly polarized light P2 (required polarized light) parallel to the upper electrode plane ABCD can pass through the electro-optical crystal 200 without loss, and linearly polarized light S2 (unnecessary polarized light) perpendicular to the upper electrode plane ABCD is mostly reflected, which also plays a role in suppressing residual amplitude modulation caused by birefringence of the electro-optical crystal.
And (3) experimental verification:
the electro-optical crystal 200 is a lithium niobate crystal, the width (distance between two reflecting surfaces) H of the lithium niobate crystal is 5 mm, the thickness (distance between an upper electrode surface ABCD and a lower electrode surface a 'B' C 'D') H of the lithium niobate crystal is 4 mm, a laser beam is reflected times (j is 1) on a second reflecting surface CDC 'D', a portion where the upper electrode surface ABCD and the lower electrode surface a 'B' C 'D' are directly opposite is plated with a conductive gold film, the refractive index n of incident light O (ordinary ray) to 780nm of the electro-optical crystal 200 is 2.15 assuming that the electro-optical coefficient γ of the electro-optical crystal 200 is 31pm/V and the wavelength λ of the laser beam is 780nm, and the side length AB of the lithium niobate crystal can be obtained by the above-mentioned parameter relationship as 28.56 mm.
Open the microwave signal source, and use the radio frequency cable to connect the signal source with the utility model discloses radio frequency circuit 300 in the electro-optic phase modulator, make radio frequency circuit 300 produce the electric field between the last electrode face ABCD of electro-optic crystal 200 and lower electrode face A 'B' C 'D', 780nm laser beam passes through the unthreaded hole from casing 100 and gets into behind the electro-optic crystal 200 from another clear light hole outgoing, the emergent light reachs photoelectric detector after focusing, lead-in surplus amplitude modulation measurement system (by real-time spectrum analysis appearance, the mixer, FFT analysis appearance and digital voltmeter constitute with photoelectric detector output signal).
The residual amplitude modulation measured by the residual amplitude modulation measuring system is about 2 x 10-5Residual amplitude modulation (10) than that produced by conventional electro-optic phase modulators-3Magnitude) is reduced by two magnitudes, and the influence on precise atomic spectrum experiments is not obvious.
Claims (10)
- The electro-optical phase modulator comprises a shell (100), an electro-optical crystal (200) and a radio frequency circuit (300), wherein the electro-optical crystal (200) and the radio frequency circuit (300) are arranged in the shell (100), the electro-optical crystal (200) comprises an upper electrode surface ABCD, a lower electrode surface A 'B' C 'D', a light passing surface ACA 'C', a second light passing surface DBD 'B', a light reflecting surface ABA 'B' and a second light reflecting surface CDC 'D', A, B, D, C are respectively sequentially marked on four vertexes of the upper electrode surface, and A ', B', D 'and C' are respectively sequentially marked on the four vertexes of the lower electrode surface;the two opposite side walls of the shell (100) are respectively provided with an th light through hole (102) and a second light through hole (101), and the side wall of the shell (100) is also provided with a radio frequency signal adapter (103);two signal input electrodes of the radio frequency circuit (300) are respectively connected with two electrodes of the radio frequency signal adapter (103), and two signal output electrodes of the radio frequency circuit (300) are respectively connected with an upper electrode surface ABCD and a lower electrode surface A 'B' C 'D' of the electro-optical crystal (200);the method is characterized in that:the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D' are congruent trapezoids and are parallel to each other; the parts, opposite to the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D', are plated with conductive films;the light passing surface ACA 'C' and the second light passing surface DBD 'B' are both positioned between the upper electrode surface ABCD and the lower electrode surface A 'B' C 'D' and are symmetrical about the centerline of the upper electrode surface ABCD;the th reflecting surface ABA 'B' and the second reflecting surface CDC 'D' are parallel and are both vertical to the upper electrode surface ABCD, and the th reflecting surface ABA 'B' and the second reflecting surface CDC 'D' are both plated with medium total reflection films for the light wavelength passed by the electro-optical crystal;an included angle between the th light reflecting surface ABA 'B' and the th light passing surface ACA 'C' and an included angle between the th light reflecting surface ABA 'B' and the second light passing surface DBD 'B' are complementary angles of Brewster angles;the optical axis direction of the electro-optical crystal (200) is the direction from the th light reflecting surface ABA 'B' to the second light reflecting surface CDC 'D';the length of the long side of the th light reflecting surface ABA 'B' is calculated according to the formulaDetermining, wherein n is the refractive index of the electro-optical crystal (200) to the ordinary light, h is the distance between th reflecting surface ABA 'B' and the second reflecting surface CDC 'D', and j is the reflection number of the light beam on the second reflecting surface CDC 'D';
the th light passing hole (102) corresponds to the th light passing surface ACA 'C', the second light passing hole (101) corresponds to the second light passing surface DBD 'B', and the central axes of the th light passing hole (102) and the second light passing hole (101) are parallel to the th light reflecting surface ABA 'B' and the second light reflecting surface CDC 'D' and pass through the geometric centers of the th light passing surface ACA 'C' and the second light passing surface DBD 'B'. - 2. A low residual amplitude modulated electro-optic phase modulator according to claim 1, characterized by: the angle error between two adjacent faces of the electro-optic crystal (200) is not greater than 2 angular divisions.
- 3. A low residual amplitude modulated electro-optic phase modulator according to claim 1, characterized by: the parallelism between two parallel surfaces of the electro-optical crystal (200) is not more than 2 angular divisions.
- 4. The electro-optic phase modulator of claim 1, wherein the th light passing surface ACA 'C', the second light passing surface DBD 'B', the th light reflecting surface ABA 'B' and the second light reflecting surface CDC 'D' each have a surface roughness of better than 0.008 μm.
- 5. The electro-optic phase modulator of claim 1, wherein the reflectivity of the th reflecting surface ABA 'B' and the second reflecting surface CDC 'D' is not lower than 99.7%.
- 6. A low residual amplitude modulated electro-optic phase modulator according to claim 1, characterized by: the conductive film is a gold film.
- 7. A low residual amplitude modulated electro-optic phase modulator according to claim 1, characterized by: the shell (100) is made of copper materials.
- 8. The electro-optic phase modulator of any of claims 1-7 and wherein the distance between the upper electrode plane ABCD and the lower electrode plane A 'B' C 'D' is greater than the diameter of the incident beam.
- 9. A low residual amplitude modulated electro-optic phase modulator according to claim 8, characterized by: the electro-optic crystal (200) is a lithium niobate crystal, a magnesium-doped lithium niobate crystal or a potassium titanyl phosphate crystal.
- 10. A low residual amplitude modulated electro-optic phase modulator according to claim 9, characterized in that: and the lower electrode surface A 'B' C 'D' is provided with conductive adhesive, and the electro-optic crystal (200) is fixed in the shell (100) through the conductive adhesive.
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| CN201920675611.4U CN210005814U (en) | 2019-05-13 | 2019-05-13 | electro-optic phase modulator with low residual amplitude modulation |
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| CN201920675611.4U CN210005814U (en) | 2019-05-13 | 2019-05-13 | electro-optic phase modulator with low residual amplitude modulation |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110187525A (en) * | 2019-05-13 | 2019-08-30 | 中国科学院西安光学精密机械研究所 | A kind of electro-optic phase modulator of low residual amplitude modulation |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110187525A (en) * | 2019-05-13 | 2019-08-30 | 中国科学院西安光学精密机械研究所 | A kind of electro-optic phase modulator of low residual amplitude modulation |
| CN110187525B (en) * | 2019-05-13 | 2024-01-30 | 中国科学院西安光学精密机械研究所 | Electro-optic phase modulator with low residual amplitude modulation |
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