CN1039309A - Optical isolator of garnet mouocrystal mingled with in, bi, ca and v - Google Patents

Optical isolator of garnet mouocrystal mingled with in, bi, ca and v Download PDF

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Publication number
CN1039309A
CN1039309A CN88103982A CN88103982A CN1039309A CN 1039309 A CN1039309 A CN 1039309A CN 88103982 A CN88103982 A CN 88103982A CN 88103982 A CN88103982 A CN 88103982A CN 1039309 A CN1039309 A CN 1039309A
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China
Prior art keywords
faraday rotator
optoisolator
garnet
faraday
mouocrystal
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CN88103982A
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Chinese (zh)
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马晓明
陶尚平
张鹏翔
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Individual
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/0009—Materials therefor
    • G02F1/0036—Magneto-optical materials
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/09—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on magneto-optical elements, e.g. exhibiting Faraday effect
    • G02F1/093—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on magneto-optical elements, e.g. exhibiting Faraday effect used as non-reciprocal devices, e.g. optical isolators, circulators

Abstract

The present invention relates to the magneto-optical element of forming by crystal in the optoisolator, promptly make faraday's optically activ material and make Faraday rotator with garnet mouocrystal mingled with In, Bi, Ca and V.This crystal does not contain rare earth element, and growth is easy, and volume is big, yield rate height, easily processing.And the very high magneto-optic figure of merit and low saturation magnetization are arranged.Both greatly reduce the cost and the cost of Faraday rotator, helped miniaturization of devices again.In technical fields such as optical fiber communication, Fibre Optical Sensor, high resolving power interferometry and magnetooptic recordings very big practical value and challenging IP prospecting are arranged all.

Description

Optical isolator of garnet mouocrystal mingled with In, Bi, Ca and V
The present invention relates to a kind of device of controlling the transmission direction of light,, or rather, relate to the magneto-optical element of forming by crystal in the optoisolator promptly about massive material type optoisolator.Belong to the lightwave technology field.
Optical fiber communication is as the most attractive a kind of brand-new communication technology in the present age, because little, in light weight, the anti-electromagnetic interference performance of itself peculiar volume is strong, bandwidth, advantage such as transmission capacity is big, transmission range is long and cost is low, fast and the range of application of speed of development is wide, has exceeded people's the expectation and the imagination.Abroad, formed an emerging optical fiber communication industry already.Particularly American and Britain, day, they have been used for optical fiber transmission technique technical fields such as various communications, radio and television, industry, traffic, aircraft, guided missile, naval vessels, nuclear base data transmission, extra large cable and sensor at present.Now, the long-wavelength single-mode optical fiber transmission that optical fiber communication is just farther towards transmission range and message capacity is bigger and the direction of light coherent communication develop.For in optical fiber telecommunications system, prevention enters semiconductor laser along the echo reflection at random of fiber channel with prevention reflected light or scattered light, cause laser characteristic to worsen, and in fiber optic network (as computer network), pulse distortion even error code that inhibition produces because of reflection wave, must be hinged with optoisolator between laser instrument and the optical fiber and between optical fiber and the optical fiber,, make the laser instrument vibrational stabilization and reduce loss to reduce reflecting background.
This optoisolator is to utilize the characteristics of non-reciprocity of Faraday magnetooptical effect to make, its principle is the polarization direction to be inserted between the polarizer 1 of deflection 45 and the analyzer 3 left the Faraday rotator 2 of polarization direction rotation 45 is constituted at transmission-polarizing light as shown in Figure 1.When light positive during to incident, light becomes linearly polarized light after by the polarizer 1, and again by after the Faraday rotator 2, light polarization direction is to 45 ° of anticlockwises, and is just consistent with the polarization direction of analyzer 3 and can pass through smoothly with very little loss.And when reflected light incident in the other direction, behind analyzer, the polarization direction is consistent with the analyzer direction, again by behind the Faraday rotator, because the characteristics of non-reciprocity of faraday's rotation, be the direction that direction that faraday rotates only is decided by externally-applied magnetic field, and with the orientation independent of light transmission.So the polarization of reflected light direction is just in time vertical with the direction of the polarizer again to 45 ° of anticlockwises, loss can not be passed through too greatly.So just suppress reflection of light, played the effect of isolating.Among Fig. 1, solid line is an incident light, and dotted line is a reflected light.
Technology, economic performance requirement to optoisolator are:
(1) little to the insertion loss of forward incident light;
(2) isolation of back reflection light is wanted big;
(3) volume is little;
(4) low cost.
Faraday rotator is the key component in the optoisolator, and its performance quality directly determines the quality of optoisolator performance.The anglec of rotation of Faraday rotator depends on the length of Faraday material and the intensity of externally-applied magnetic field.If externally-applied magnetic field is enough strong, make the Faraday material reach magnetic saturation, then the rotation angle of Faraday rotator only depends on the length of Faraday material.Consider the cause of stability, Faraday rotator all is operated under the magnetic saturation state, is the may command rotation angle by the length of selecting faraday's optically activ material.
Major technique, economic performance requirement to Faraday rotator are:
(1) low light absorption loss (low insertion loss);
(2) big faraday's coefficient of rotary;
(3) High Extinction Ratio;
(4) low saturation magnetization;
(5) low production cost.
Yttrium iron garnet (YIG:Y 3Fe 5O 12) monocrystalline in 1.1 microns～1.7 microns (μ m) wave bands of near infrared, good rotary light performance (rotation angle is big) and less absorption loss are arranged, so be widely used for manufacturing the Faraday rotator in the optoisolator at present, result of use is also better.
For example: " electronics wall bulletin " (the Electronics Letters) in 1985 reported (the AT﹠amp of AT﹠T on the 18th phase; T) Bell Laboratory is made the situation of optoisolator of YIG.They select the easy magnetization of YIG＜111〉direction, as optical axis direction, add refractive index matched liquid at the interface place of polariscope and YIG again, also plate the counnter attack film on polariscope end face and YIG end face, the purpose of taking these measures all is will increase isolation as much as possible and reduce the end face reflection loss.After taking above-mentioned three measures, to 1.7 mu m wavebands, isolation 〉=32dB is at 1.55 mu m wavebands at 1.2 μ m for the YIG optoisolator that they make.Isolation is about 36dB; And insert loss at 1.2 μ m places.Being 3.4dB, is 1.5dB at 1.3 μ m places, is 0.8dB at 1.55 μ m places.
On the 5th phase, reported that the optoisolator of British Telecommunications Research Establishment development still uses yig crystal at " electronics wall bulletin " (the Elcctronics Lctters) in March in 1988 again, its isolation is 31dB at 1.5 mum wavelength places.
But there are two problems in the YIG Faraday rotator: the one, and the cost price problem.Owing to contain expensive rare earth element yttrium (Y) in the yig single crystal, make the prices of raw and semifnished materials expensive.And crystal growth temperature is higher, growth is difficult, and yield rate is low, makes the monocrystalline production cost rise again.And, because the faraday of yig single crystal rotation is not very big, make that the Faraday rotator length of making is longer, as at 1.3 μ m～1.55 mu m wavebands, the length of YIG Faraday rotator is about 2.1～2.6mm, so, need yig single crystal with larger volume, make the Faraday rotator cost very high, the optoisolator natural price of making is also high, is unfavorable for promoting practical.Moreover, the composite fluxing agent massicot+bismuth oxide (PbO-Bi that in the YIG single-crystal growth process, uses 2O 3) high volatility, lead poisoning pollution and corrosivity are also strong.The 2nd, the device volume problem.Because yig single crystal saturation magnetization higher (about 1800 Gausses), so must just can make it reach magnetic saturation with larger-size strong magnet, this just be unfavorable for miniaturization of devices.
In recent years, the someone studies with gadolinium iron garnet (BiGdIG) monocrystalline of bismuth-containing (Bi) and makes Faraday rotator.This is because the gadolinium iron garnet (BiGdIG:Gd of bismuth-containing 3-xBi xFe 5O 12, x 〉=1) and at infrared band very big faraday's rotation angle Q is arranged FLow relatively light absorption α (that is: the absorption loss of unit length) that is to say that this material has the high magneto-optic figure of merit (Q F/ α), so with the Faraday rotator that it is done, length has only 0.3～0.5 millimeter.The saturation magnetization of BiGdIG is also low than YIG, is about 1200 Gausses, so externally-applied magnetic field is also weak slightly.
Introduced the optoisolator situation that northeastern Japan (Tohoky) university manufactures with BiGdIG on the 2nd phase at " applied optics " (Applied Optics) of Optical Society of America in 1986 magazine, they select another direction of easy axis＜110〉direction is optical axis direction, the index that isolator reaches is: at 1.29 mum wavelengths, isolation is 28dB, and inserting loss (not comprising Fresnel reflection-end face reflection) is 1.9dB; At 1.52 mum wavelengths, isolation is 31dB, and inserting loss (not comprising Fresnel reflection) is 1.1dB.But the cost price problem is still unresolved, and this is that the crystal growth yield rate is lower, so the monocrystalline cost still can't reduce because contain expensive rare earth element (Gd) equally among the BiGdIG.The performance index that add the optoisolator of making are also poor slightly than the performance of YIG optoisolator.Therefore, still extensively adopt YIG to manufacture optoisolator at present in the world.
The optoisolator that the objective of the invention is to provide a kind of magneto-optic memory technique that adopts low cost, low saturation magnetization to manufacture is to overcome the defective that above-mentioned prior art exists.
Optoisolator of the present invention also is made up of the polarizer, Faraday rotator, permanent magnet and analyzer etc., Faraday rotator wherein then be by garnet mouocrystal mingled with In, Bi, Ca and V as the Faraday material, alternative yttrium iron garnet is made.
The ratio of the composition of indium, bithmus, calcium and vanadium garnet (BiCaInVIG) monocrystalline that adopts among the present invention (structural content ratio): Bi 3-2xCa 2xFe 5-x-yIn yV xO 12, x=0.8～1.4, y=0～0.4.This crystal has the high magneto-optic figure of merit, and faraday's rotation angle is higher 4～6 times than YIG's, so the length of Faraday rotator is also than 4～6 times of the weak points of YIG.The prices of raw and semifnished materials are cheap, cheap 70～100 times than YIG starting material because BiCaInVIG does not contain rare earth element! And crystal growth is easy, and temperature is lower, and the crystal volume is big, yield rate height, processing easily.Add that the flux volatility of using in the single crystal growth process is low, toxicity and corrosivity are also low.Make Faraday rotator with it, greatly reduce the cost cost of Faraday rotator, the cost of optoisolator is also descended greatly.And the saturation magnetization of BiCaInVIG monocrystalline is very little, has only 0～500 Gauss, and is more much lower than YIG.So, only need very weak magnetic field that it is worked under saturation magnetization, very favourable to miniaturization of devices.Therefore, practical value of the present invention is very big, has very obvious and tempting IP prospecting.
Introduce embodiments of the invention below in conjunction with accompanying drawing 2.
Accompanying drawing 2 is optoisolator-synoptic diagram of the present invention-make with BiCaInVIG.As shown in the figure, this optoisolator comprises: the polarizer 4, make Faraday rotator 5, permanent magnet 6, analyzer 7 and the housing 8 of magneto-optical element of BiCaInVIG.Wherein the effectively logical optical cross-section area of Faraday rotator BiCaInVIG is 1～6mm 2, its length is 400～700 μ m, much smaller than the length of yig crystal.In experiments such as coherent optical communication system, we develop the optoisolator of enforcement at 1.3 μ m and 1.55 mum wavelengths, performance index are: insert loss＜1.0dB(and comprise about the end face Fresnel reflection loss 0.8dB of the polarizer and analyzer), isolation 〉=35dB.Respond well.Under the situation of not taking any other antireflection measure, play the effect of inhibitory reflex influence effectively.

Claims (5)

1, the optoisolator made of a kind of characteristics of non-reciprocity that utilizes Faraday magnetooptical effect is made up of the polarizer, Faraday rotator, permanent magnet and analyzer, it is characterized in that Faraday rotator wherein makes with garnet mouocrystal mingled with In, Bi, Ca and V.
2, optoisolator according to claim 1 is characterized in that the ratio (structural content ratio) of the composition of indium, bithmus, calcium and vanadium garnet (BiCaInVIG) monocrystalline is Bi 3-2xCa 2xFe 5-x-yIn yV xO 12, x=0.8～1.4, y=0～0.4.
3, optoisolator according to claim 1 is characterized in that the saturation magnetization of indium, bithmus, calcium and vanadium garnet (BiCaInVIG) monocrystalline is very low, in 0～500 Gauss's scope.
4, optoisolator according to claim 1 is characterized in that the length of the Faraday rotator made with garnet mouocrystal mingled with In, Bi, Ca and V is 400～700 microns (μ m).
5, optoisolator according to claim 1 is characterized in that the diameter of section of the Faraday rotator made with garnet mouocrystal mingled with In, Bi, Ca and V is 1～6 millimeter.
CN88103982A 1988-07-04 1988-07-04 Optical isolator of garnet mouocrystal mingled with in, bi, ca and v Pending CN1039309A (en)

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Application Number Priority Date Filing Date Title
CN88103982A CN1039309A (en) 1988-07-04 1988-07-04 Optical isolator of garnet mouocrystal mingled with in, bi, ca and v

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Application Number Priority Date Filing Date Title
CN88103982A CN1039309A (en) 1988-07-04 1988-07-04 Optical isolator of garnet mouocrystal mingled with in, bi, ca and v

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102279478A (en) * 2010-06-12 2011-12-14 北京优立光太科技有限公司 Optical isolator
CN101201261B (en) * 2006-12-08 2012-03-21 通用电气公司 System and method for integrated measurement using optical sensors
CN110346869A (en) * 2019-06-11 2019-10-18 北京兆维智能装备有限公司 A kind of production method of the optical waveguide isolator based on femtosecond laser photoetching technique
CN112930470A (en) * 2018-09-04 2021-06-08 省卫生服务局 Image guided micro-raman spectroscopy

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101201261B (en) * 2006-12-08 2012-03-21 通用电气公司 System and method for integrated measurement using optical sensors
CN102279478A (en) * 2010-06-12 2011-12-14 北京优立光太科技有限公司 Optical isolator
CN112930470A (en) * 2018-09-04 2021-06-08 省卫生服务局 Image guided micro-raman spectroscopy
CN110346869A (en) * 2019-06-11 2019-10-18 北京兆维智能装备有限公司 A kind of production method of the optical waveguide isolator based on femtosecond laser photoetching technique

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