JPS5924827A - Optical gate modulating method and optical gate - Google Patents

Abstract

PURPOSE:To perform high-speed and various modulations with a simple constitution, by giving modulations of the same modulation frequency but of a different phase, to plural light intensity modulators by a modulation driving power source and modulating lights successively to emit them. CONSTITUTION:Modulating electrodes 21-23 different in optical path length are provided on the surface of an electrooptical crystal 20 in accordance with predeterminate optical paths, and a common electrode 24 is provided on the rear face, thus forming a light intensity modulator having different modulation sensitivities. A modulation driving power source 25 is connected to the modulating electrode 21 and the common electrode 24, and modulating electrodes are connected by high frequency paths 26 and 27, and the modulating electrode 23 is connected to the common electrode 24 through a resistive terminator 28, and the lengths of high frequency paths 27 and 28 are adjusted to synchronize with light in accordance with propagation of light. A modulation bias adjusting electrode 29 is provided between electrodes 29 and 24. An incident light 36 has the intensity modulated through the electrode 21 and an analyzer 31 and is reflected by a reflective mirror 34 and is light modulated by the electrode 23 and an analyzer 32 and is reflected by a reflective mirror 35 and is modulated by the electrode 23 and an analyzer 33 and is emitted as a light 37. Consequently, high-speed various modulations are performed with a simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention consists of
(Regarding a light gate applying the method.

As a short-time gate (optical switch) for optical signals, &J tv, optical modulator #74 or sound! optical modulator 61 has conventionally been used.When using these modulators conveniently, , I for 1lit with the same gate width as these.
ff.

Air pulses or acoustic pulses are required, or such pulse widths are short and long, from ns to ps.

It is difficult or impossible to obtain a small oscillatory pulse to the tee ratio. This is why obtaining such a short optical gate is expensive.

On the other hand, two theoretical methods have recently been proposed in the United States that make short-term optical gates possible using the optical effect.

The first method is E, A, J, of Bell Laboratories in the United States.
[Applied op.
tics vol・19 p1468-1476 (1υ
80]). In this first method, as shown in FIG. 1, the optical gate is provided with two optical waveguides 2 and 8 in parallel near the surface of an electro-optic crystal l, and electrodes 4 and 5 are provided on these optical waveguides. are provided respectively, and the structure is such that a high frequency voltage can be applied from a high frequency power source 6 to one of these electrodes. In this case, there is a weak coupling between the two waveguides jll'+ 21 s, and when no 11'L field is applied, the optical propagation connections of both the special wave paths are almost equal. In addition, we have determined the 111-field Muin force former I, and the optical beam P0 entering one waveguide 2 is almost completely transferred to the waveguide 8 at the output section of the optical gate. Output as a light beam P! l-
It has become so. 111 of this light gate. When a voltage is applied between the poles, two ! A difference occurs in the light propagation constants of the waveguides 2 and 3, so that the transition of the light beam from the waveguide 1 to the waveguide 2 is reduced or eliminated. Therefore? 'I polarity 4.
When a high frequency voltage is applied between 5 and 5, the voltage is small between 1 and 1 (
The light beam P1 incident on the waveguide 2 of this optical gate will be shifted from the waveguide 1 to the waveguide 2 only when it occurs twice in one week. J:.

During the time when the beam is small, it transfers to the waveguide 3 and outputs it as a light beam P8, and at other times no transfer occurs, so that the original beam J\P1 and the complement of the original beam J\P1 and the beam P8 are transferred from the original waveguide 2. output as a signal, so that this light gate can act as a light gate for a short time. In addition, Po.

P8. The intensities of these light beams are schematically shown beside P.

However, in the y6 gate according to this first method, μ
Since a waveguide of m size is theoretically required, there are disadvantages in that high power light cannot be removed from the viewpoint of optical damage, and advanced manufacturing technology is required. Furthermore, in the optical gate of this first type, it is difficult to match the driving electric signal, which is unreliable for Takatsushi operation, with the timing of the light, so it has not been actually realized.

The second method is H0A of Matsuthusetse University of Technology in the United States.
J (IE
EEJournal of Quantum Elec
tronic vol, 1. QE-16゜p870~
873. (1980)).

The optical gate according to this second method (1 x Jt each 4i + y) has an amplitude of 4, IW!
Frequency force (2ω.

(However, N-1, 2, 8...) (this jl(
＠Next number, double, different light intensity quality 11! This second type of optical gate σ) will be explained below.

Now, there is no loss other than Transform I4, 11L Ki Optical Transform 117
(ma □2 bias'e, the same or Q between two light waves) If the optical degree difference 1 is θ(1), the original overstrength T(t) can be expressed as follows. Here, Oo is ノ<-(first position
4, ΔU is the −1·4 phase handling width, f is the modulation frequency, and t is time. Now, θ. When set to −〇 (or an integer multiple of π), equation (1) becomes. Here, further assume ΔU-π (radian) and f''-2p-1・fo(p-1, 2,...M i
If f (1 - basic frequency 111), then (8)
From the formula. In this equation (4), p-1+2 and Q
・Three 111 Qi Gakusame 1; 1, Mouth N is this I
IIL (series in sequence (this arrangement r', + the light transmission intensity of each electro-optic modulator itself, that is, modulation! lj
, I characteristic T1,2.3(t) and the composite light transmission intensity of the light output from the final stage, that is, the composite change of the three stages of composite modulation,'
a 'h property Ttot(t)-T,(t)-T2(t)
-T8(t), and these descriptions and the eighth
As is clear from Figures (a) to (d), the final output of this optical gate is t. .

1, , 12.18 . . . , a narrow pulse-like output reaches its maximum peak at times 1, , 12.18, . . . . Therefore, such an electro-optical transformer W1'4 is sequentially converted into M19 (however, p-"+
"+...M) +IJ- When arranged in the column t&, the period of the M stage transmission light gate is the first stage variable 1 which has the longest period, and the transmission gate lll+a is the fastest one. Friend Wt device (1)-M) is capable of obtaining a pulsed light beam with a small duty ratio that cannot be obtained with a general configuration.

In the optical gate according to the second method, it is not an essential issue whether or not to form a waveguide structure in the electro-optic crystal, so in the optical gate according to the first method, the optical power limit and the production Although the above-mentioned ltl & ili characteristics are not so important, there is a huge drawback in that modulation drive power supplies of different frequencies must be separately prepared for each modulator in each stage. Furthermore, the size of variable t (
If ΔV) in equation 3) is made larger than about π, the gate waveform will collapse, so this Δθ cannot be selected so large. ) is required. For example, to obtain a 1 pS optical gate, 1
A variable w1°d operating at 67 GHz is required. However, in order to drive the transformer at high frequency,
& It is extremely difficult to obtain a self-driving commode, and it is strange+p,'a
This also causes problems with the electrical circuit of the device (for example, stray capacitance between electrodes), and furthermore, as mentioned above, speed matching becomes extremely difficult. This second type of gate also has these drawbacks, so it has not yet been put into practical use.

An object of the present invention is to provide an entire optical gate modulation method (σ) that is completely different from the conventionally proposed optical gate modulation methods described above.

A further object of the present invention is to provide an optical gate variable crystallization method in which the optical gate can be made into a simple 111 structure by using a single variable 1i14 drive 71 source that is easy to handle.

Roughly speaking, the purpose of the present invention is to handle a large amount of light and to miniaturize the collection. An object of the present invention is to provide an optical gate modification WrA method that allows obtaining a high-speed optical gate.

Still another object of the present invention is to provide an optical gate variation FJ4 method that can control the total modulation transmission waveform of the optical gate in various ways.

Still another object of the present invention is to provide an optical gate to which this optical gate changing θ11 method is applied.

In order to achieve these objects, according to the present invention, when the light incident on the light gate which sequentially includes a plurality of light intensity modulators in the optical path is outputted with Rt94, one variable W1 The same modulation frequency is commonly given to all the light intensity modulators from the power supply, and the variable, +fi phase amplitude, modulation bias phase and The 1ζ'r characteristic is to make different modulation factors selected from each variable W1'1 factor of the quick-read high frequency phase to give different modulation characteristics to each of the optical intensity modulators. shall be.

Furthermore, in a preferred embodiment of the invention, all N 0
iJ write optical jjiji degree modulation gain change, v1''1 bias phase () or an integer of π (radians) (j'i and J
(However, j-1, 2, . . . N)th optical intensity modulator change ii1. 'i phase amplitude'l'iil πx 2]-' (
radians).

Furthermore, according to the original gate of the present invention, IIIJ is present in the optical path.
Next, a number of optical intensity modulators are arranged, each having different modulation characteristics. It is characterized by comprising one variable NrA drive voltage τlb- connected thereto.

Embodiments of the present invention will be described below with reference to the drawings.

First, the principle of heathering will be explained.

Assume now that a plurality of light intensity variable loops are arranged in series in N narrow optical paths to form a light gate. The light intensity variation of the first stage of the Jth scan, the 11 factors of each variation of the ν1′j device, that is, the bias phase are U. J, the modulation phase amplitude is Δθ, and the high frequency phase when variable Wj is α, then J
W LT (D light 'jm U'!? key'd# (
1,) light r JICIo IIL Tj (shi) is (3)
From the formula (however, J-1+2+...N) is obtained. this(
5) The value in brackets on the right side of the equation is π (an integer multiple of radianno (0
), then Tj(t) ~ 1 in the vicinity of 1iJ1 t
, and a peak appears at 6 super-strong pulls.

The inside of this gate, ie, the gate 1lIljl, is changed to 1. i (The large culm becomes shorter, but at the same time, the number of peaks that appear in one cycle also increases, so the light intensity L of only one stage (the modulator requires a high-quality short-time gate) cannot be obtained.

On the other hand, the modulation characteristics, i.e.,
One light beam passes through an optical gate in which, for example, N light intensity transformers ρ1′l with different values (t) are arranged in series in the optical path, 7! Ij
Degree T. 1(t) is Ttot(t)-T1(t) x
T2(t) x ・T, (t) (o) is given. Therefore, even if we give each of the optical Jn 1-degree modulators the same driving variable Ia of common m and the rotation t)12i, the variable 11·1 phase jlA 'l'i11 which is the inner child of the variable 8N4
ΔOv 1 change θ1′4 bias Ij″f phase (' 0 ]
, by appropriately selecting the variable ril:i high phase α for each optical intensity modulator individually.
These light intensity 1 variable 1 Dil devices are each 4J English.
By giving the 1v characteristics of the 1V, and by combining these important compatibility, we can understand 11! from the light gate! J optical gate waveform and other 4'
! It is possible to obtain 'A-fu', 'i-characteristic, and variable R'-waveforms that cannot be obtained with a single optical intensity modulator, such as optical gate waveforms of various shapes.

The present invention is based on such a principle, and all light and strong refutations 1i11'! The same relatively low modulation layer r11 number is commonly given to the optical gates from a single frequency driving source, and the respective variables 111 factors are appropriately considered for each optical intensity modulator. The nature of composition, that is, the synthetic change W,
'1 characteristic is set to a certain value. Furthermore, 1
) The modulation frequency described in 11 is the same for all optical intensity modulators.
■You can also change it to 1.

FIG. 3 shows an example of 71<
The small axis has the iM excess light intensity T1(t),
Tz(t) and To(L) + T@0z(t) are respectively taken, and it is taken as 4'&i 11ql+, respectively. In this case, the optical gate is set to 3 stages + 1i "I" and 7
, each one light intensity variable one variable 'fJr4! Toshi nature, that is, light J passed 'jilt Idan', ['ko(t) (
However, there is a difference between the waveform of J''-1+''+8) and the overall modulation characteristic, that is, the overall transmission intensity. t(t)-T yo(t)X
T2(shi)X T8(t,) waveforms are shown in +11vt in FIGS. 3(a) to 3(d). In this case, the bias phase U. phase α3 ” 0 to the co 0 and modulation upper υ
and the front leg and kNj overphase oscillation ΔOJ−πX2J−′(
j-1+2+8). From the calculation example shown in Fig. 8, the gate width of this 8-stage optical gate is 3 times one period.
It becomes very short to about ~4%, and from this it is possible to obtain a small original pulse gate to the Tutey ratio.

Next, an example of the basic configuration of an optical gate to which the modulation method of the present invention is applied will be explained with reference to FIG.

In Fig. 4, 10-1 to 10-N are optical gates 1
In order to create an image, there are N (N": 2'2) light intensity side 1."1 devices arranged in the original 1st order 11' row in the optical path, and these strange 'e! (1) The crystals may be individually formed into one crystal per month, or one crystal may be formed individually. The change θ・1 of the first stage of this light gate
The incident light 13 entering from the left side of the vessel 10-1 is output from the right side of the Nth stage. Note that 14 indicates the emitted light. 12 is variable iu; 1 drive 111. In the section, the maximum is several tens of Gf (z l□ 1 degree circular mantissa, and with this 1 repetition motion 1 u 1 chant, each of the units 10-1 to 10-N are all driven at the same 1 degree frequency) Then, as mentioned above, the change 1ν, □1+ !tar property of each stage is y4
normalizing, so that K factor, i.e. modulation bias phase, modulation phase amplitude and variation W, 'd varies high frequency phase, lL
Each percentage is set individually. This modulation bias
“The f phase is the phase of light, for example the known internal and external rfR
It can be set by optical or tit optical means. Furthermore, in order to change the modulation phase 3'k ll'f+1, for example, in addition to adjusting the modulation power or voltage supplied to each stage, there is also a method of changing each stage! There are methods such as changing the length of the J tli pole, changing the modulation sensitivity of each stage, and combining these methods. To change the modulated high frequency ()L phase, for example, change the high frequency phase shifter and change the 11 station frequency drive power supply and each i! 1. It is also possible to use it as a substitute for a wave phase shifter in height 1 by providing it between two transformers or by adjusting the island frequency line length, optical path length, and force between each transformer. Therefore, in the basic configuration example shown in FIG.
1' The modulation bias phase corresponding to each stage number of the device and the force or voltage or modulation sensitivity of each stage corresponding to each stage number are changed to a total change of the entire optical gate i11! The value of the harmonic sum is set to 1 so that the l characteristic has the required characteristic, and the variable 1νj transformers 10-1 to 10-N of each stage and y<electrodynamic fA12
and 1. High frequency phase shifter 15-
1.15-2.15-8, 15-(N-
1) The phase shifter 15-N is used to individually correct the shift in the modulation timing caused by the difference in the transit time of the high frequency wave used for the light and the variable W1 for each θ11 device, or I/MG, please actively shift the K key timing to flj control the gate waveform of the optical gate to the required waveform.

As can be seen from the basic configuration example shown in FIG. 4 above, the light fA displacement W of each stage arranged in series in the optical path constituting the light gate is expressed as the vessel variation θ, Shooting width, Ki1
! The l bias phase and the variable W1°4, t, i511d slope phase are determined by law to make the variable mad characteristics of the modulators at each stage different, and the overall change of the entire optical gate is made. fJ: 4 Q, 'I property (variable W1 + A waveform is also n゛)
This means that you can choose from a variety of options.

Next, using FIG. 5 and FIG. 6, what is the optical gate of the present invention and its variations? A specific example of the J11 force method will be explained. In each of the embodiments, a case will be described in which the light intensity changer jjli, j has eight stages.

In the embodiment of the optical gate shown in FIG.
ti, corresponding to the planned optical path, the first . second and eighth modulation electrodes 21';
22.11 is provided, and a common 1L pole 24 is provided on the other surface to form eight light intensity modulators W1'i each having a different sensitivity and having four sensitivities arranged sequentially in the optical path. In order to apply harmonic voltage for modulation to each of these four changers,
strange? The Jjg driving power source 25 is connected between the first variable Wjd electrode 21 and the common electrode 24, and is further connected between the first and second modulating electrodes 21 and 22, and between the second and third variable electrode 1a electrode 2.
2 and 28 are connected by high-frequency lines 26 and 27, respectively.
llj L', furthermore σ) 3rd poor it! ! ? W
Jmu(wo)r+<Reflection end 28 both 1FJJ 7t
'b connected to pole 24, thus iw ray, 25,
&-IL These 6 electric IJJ, 21, 22, 28
are connected in series). By appropriately selecting the lengths of these high-frequency lines 26 and 27, the propagation of the high-frequency voltage 11 (between a and 117r and the phase σ) iν・a can be adjusted so that it can be synchronized with the light according to the propagation of the light. 29 changes the Ias phase by a change of 1'd.
A modulation bias voltage is provided in accordance with the nr value for the target Fjr (shown with a line in the figure), and a power supply connected between this 'IIf, g429 and the common electrode 24. By adjusting the pressure from 80 to 80, the phase of the light can be adjusted to v4. In the figure, it is 31°, 32.
88 is an analyzer, and 34.35 is an optical element such as a prism or a reflection mirror.

In this optical gate, incident light 86 is outputted as outgoing light 87 through an optical path indicated by a broken line in the figure. That is, the incident light 36 passes through the first variable W11 electric i+U, +21 and the analyzer 31 to have a light intensity Ni4, and then passes through the reflecting mirror (or prism) 3.
4 and then the second modulation' electrode 22 and analyzer 82.
The luminous intensity is reduced to 1u7d again at
The beam 23 and the analyzer 33 modulate the +1 degree light J+ti degrees and output it as an emitted light 37 having a general change characteristic of 1p8-. At this time, the bias phase of the light is changed to iil! via the electrode 29 at +tC at IJi+. i Adjust. 4
In the case of multiple stages of stages or more, the change in number El corresponding to the number of stages
? ii. It is good to provide poles and optical elements respectively.

The arrangement 11 of these electrodes and optical elements can be selected as desired depending on the optical path to be set. Also, a part of the emitted light 37 is detected and the signal is changed to f9.1 bias 6! Feed back 80 to % II for L
It is also possible to stabilize mAK by controlling the 1lfd bias phase by 111''.

FIG. 6 shows another specific embodiment of the optical gate of the present invention,
In this case, an optical waveguide 41 is provided in the electro-optic crystal 40 in a desired pattern, and a required 11L pole 42-1.4 is provided in a portion of the optical waveguide 41 corresponding to the modulator to be formed.
2-2; 48-1.43-2.44-1.44-2 (shown with a single line in the figure) are provided respectively. 2nd and 71st balanced bridge type light intensity changes i', l! Vessel 42
, 43 and 44. Incidentally, the number of one pole 1a for this optical waveguide may be increased as required. No need 1ki
fl % Each of these electrode sets should be used to set the capacity u・'l device! : if! ! It has a length b' which is based on the sensitivity. In addition, in one example, the drive power source 45 is connected to each of the variable Wt electrodes 4.2-1.42-2.
i 43-1 , 43-2 i 44-1 + 44-
High-frequency phase shifters 46, 4, 7, and 48 are provided for 2 to synchronize the light and the modulation driving pressure. Incidentally, instead of using this high frequency phase shifter, as shown in FIG. 5, the respective ′′ vinegar poles may be connected by a vine frequency line. In the case of this optical gate, the incident light 49 traces the modulators 42, 48, 44 along the optical waveguide 41 as shown by the solid arrows, receives a light intensity change, t, and then changes to The output light 50 has an overall modulation characteristic of m (including the variable W11 waveform).

In addition, for the electro-optic crystal and 'I(f) frame phase mentioned above, the crystal used in conventional electro-optic quick change 1Url devices and 43 size can be used, and the setting of the ?lj pole for the crystal '2' can be used. The direction is m y
/l, river 4'S (, obtained by pasting or other common methods.Furthermore, attach an electro-optic crystal to each transformer ljJ,
The light gate may be used separately, or each device may be integrated into a single TTF of 1fl, and an optical crystal; in the latter case, the optical gate can be miniaturized. As I get it lh
A1 It is possible to stabilize the length characteristics.

In addition, in the present invention, 1
one electric vein (master) or a complete book (
, +1 may be used for the first few lit units (slaves) of the same frequency.

Next, the effect of the optical gate w.1 method and optical gate according to the present invention described above will be explained.

According to the present invention, for each Kogyo Yoshitomo e#hN, the J11
1 identical variation rJ! In order to supply the h frequency, it is possible to use the & moving unit for the only variable θ7711 with a relatively low frequency that is easy to handle, and this allows the optical gate to be made into an inexpensive, small-sized, fiN-convenient LTL configuration. Along with each stage of Kouyoshi Yoshitomo θ'! <'i synchronization requires phase adjustment, but can be performed automatically.

Furthermore, according to the present invention, 111 rows of C strength filters each having different W and '1 characteristics are arranged in the optical path. Therefore, the total change of the optical gate Vr
It is possible to widen the h characteristic's ll'id k, thus turning it to r% 'R and changing the iν1°1 waveform in various ways! l
! II control, generation of 92-ton pulses, optical pulse shaping, etc.

Furthermore, it is possible to obtain a short-time optical gate of about 1 second with a small duty ratio.1. ) In addition, it is possible to obtain variable N・-lP, ν characteristics and variable L・″d waveforms that cannot be obtained with a G, 1 single optical intensity transducer.

Plus, books! According to Akira 56, since he does not use the 1M frequency that has been proposed in the past,
Since there are no undesirable problems caused by ij 11 senbin 11'c or light running bamboo effects, the construction of the TS C strength n'ta device becomes simple and easy.

Furthermore, according to the present invention, there is no necessity to provide an optical waveguide for optical signals (however, it is possible to provide an optical waveguide for miniaturization), so there is no risk of optical damage and high performance. The optical gate can be easily and inexpensively manufactured without requiring a sophisticated manufacturing technique 14, in addition to being able to take high-power light.

With this invention, it is possible to achieve a product speed gate of 161 times in a short time for optical signals from high output to low output, and also to generate wholesaler pulses, optical clock pulses, etc. Gate control (sampling detection) at I + il treetop height becomes b ■ function, and < i (
1 means communication, measurement, optical information, processing, optical technology (+I
It can be used in many directions such as research.

Furthermore, as an application example of the present invention, one series δ Tsujitsur; gate,
Short optical pulse generator, optical sambling oscilloscope,
There is one 6-wave observation instrument, 6-wave measurement instrument, and 1 other instrument.

[Brief explanation of drawings]

1st Iz° Jf Shigai (11! Figure 4J-presents for explanation of the proposed method of changing the axis of the optical gate, Figure 2 shows another optical gate modification W proposed since then, (11!) 3 is a diagram for explaining the optical gate modification method and the principle of the optical gate according to the present invention. FIG. , (Line diagram 1 for explaining the construction example of the main fishing 47'), FIG. 5, and FIG. 6 are diagrams showing specific embodiments of the optical gate according to the present invention, respectively. 10-I N10-N , 42.43.44... Light intensity variable W114 device, 12.25.48... Variable W1'1 frequency drive '71↑', +I! Le, 13,86°4υ・
...Incoming light, 14,37.50...Out! 'l=j light,
15-1 to 15-N, 46.47.48...High frequency phase shifter, 20.40...Electro-optic crystal, 21,22
,23.42-1゜42-2.43-1.48-2.4
4--1.44-2... Variable Wlt electrode, 24... Common electrode, 26.27... High frequency line, 28... Non-reflection termination, 29... Variable W4 bias adjustment electrode, 30・
...Denka, 31,32.88...Analyzer, 84°85
... Prism or reflection i, 41... Optical waveguide. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] L: Multiple light intensity levels in the optical path? In order to change the light incident on the light gate sequentially equipped with 1111′a and output it by changing θ·t, one variable is connected to the driving power source by setting all 0) f4i.
The same variable W1°1 frequency is commonly given to the light intensity modulators J, and each variation W1" of the modulation phase imaging width, modulation bias phase, and modulation high frequency phase is applied to each of the light intensity modulators.
or two or more modulation factors are made different from each other, and each of the light intensity modulators has a different modulation factor θ.
An optical gate modulation method characterized by providing 11 characteristics. LN(k'a) The variable W1t bias phase of all the optical intensity -14 devices is set to 0 or an integer multiple of π (radian), and j
(However, 'J -1+ '' +...1()-th optical intensity modulator's variable W4 phase amplitude +111i1 is πX 2,1-1
2. The method of adjusting the light gate field according to claim 1, wherein the light gate field adjustment method is set in the vicinity of (radian). & Several optical intensity modulators arranged sequentially in the optical path and each having different characteristics, and these optical intensity modulators are connected to the same frequency at a common frequency. 1 (llIj) connected to the optical intensity modulator for driving
An optical gate characterized in that it comprises a tomo Wl drive 1it.