 Vt is changed from High to Low (see FIG. 8B), the capacitance value of the variable capacitance element of the c-coupling type variable capacitance circuit is represented by Cx, and the capacitance value of the DC-cut capacitance element thereof is set to CH. In this case, the composite capacitance value Ctotal of the C-coupling type variable capacitance circuit is represented by the following formula [3].
                              C          total                =                              CH            ×            Cx                                CH            +            Cx                                              [        3        ]            
In the formula [3], when the control voltage Vt is at High (Cx=CH), the composite capacitance value Ctotal becomes CH/2. On the other hand, when the control voltage Vt is at Low (Cx=CL), the composite capacitance value Ctotal becomes CL (∵CH>>CL). In other words, the upper limit of the variation range of the capacitance value of the C-coupling type variable capacitance circuit is smaller than that of the direct-coupling type variable capacitance circuit by “CH/2”.
Thus, in the conventional improvement method described above, the capacitance can be caused to vary gradually with respect to the control voltage Vt, thereby allowing the capacitance variation in a wide range of the control voltage Vt, namely, improvement in the linearity of the oscillation frequency. However, there is a problem that because many C-coupling type variable capacitance circuits are connected in parallel, the capacitance variation ratio becomes small, and hence the variation range of the oscillation frequency of the voltage controlled oscillator becomes narrow. 1. Field of the invention
The invention is in the field of integrated opto-electronic or photonic devices that can be used for transmitting or switching optical digital data. The invention is more particularly concerned with components having a saturable amplifying medium, i.e. exhibiting a carrier depletion phenomenon, for use as wavelength converters or stabilized gain amplifiers.
2. Description of the prior art
In optical transmission systems information is usually in the form of binary data represented by pulses modulating an optical carrier wave. To carry out wavelength multiplexing and demultiplexing operations, for example in space-time switching matrices, it is often necessary to be able to carry out wavelength conversion. Wavelength conversion consists in replacing the wavelength conveying received information with another, usually different wavelength to form an output wave with the same modulation as the input wave. This conversion is advantageously accompanied by amplification and reshaping of the signal.
To enable transmission at high
Vt is changed from High to Low (see FIG. 8B), the capacitance value of the varying capacitor component of the c - coupling character variable capacitance circuit is represent by Cx, and the capacitance value of the DC - cut capacitor chemical element thereof is set up to CH. In this case, the composite capacitance value Ctotal of the vitamin c - coupling type variable capacitance circuit is represented by the succeed formula [ 3 ]. 
                               C           sum                 =                               CH             ×             Cx                                 CH             +             Cx                                               [         3         ]            
 In the formula [ 3 ], when the control voltage Vt is at High (Cx = CH), the composite capacitance value Ctotal become CH/2. On the other hand, when the control voltage Vt is at Low (Cx = CL), the composite capacitance value Ctotal become CL (∵CH>>CL). In other words, the upper limit of the variation range of the capacitance value of the C - coupling type variable capacitance circuit is smaller than that of the direct - coupling type variable capacitor tour by “ CH/2 ”. 
 Thus, in the ceremonious improvement method acting described above, the capacitance can be caused to vary gradually with deference to the restraint voltage Vt, thereby allowing the capacitor variation in a wide range of the control voltage Vt, namely, improvement in the linearity of the oscillation frequency. However, there is a problem that because many C - coupling type varying capacitance circumference are connect in parallel, the capacitance variation proportion becomes small, and hence the variation range of the oscillation frequency of the voltage controlled oscillator becomes minute. 1. Field of the invention 
 The invention is in the airfield of integrated opto - electronic or photonic devices that can be use for transmitting or switch over optical digital datum. The invention is more particularly concerned with component having a saturable amplifying medium, i.e. parade a carrier depletion phenomenon, for manipulation as wavelength converters or stabilized gain amplifiers. 
 2. Description of the prior art 
 In optical transmission systems data is usually in the form of binary datum represented by pulses modulating an ocular carrier wave. To carry out wavelength multiplexing and demultiplexing operations, for exercise in space - time switching matrices, it is often necessary to be able to carry out wavelength conversion. Wavelength conversion dwell in replace the wavelength conveyance experience information with another, usually different wavelength to form an output wave with the like modulation as the input wave. This conversion is advantageously accompanied by amplification and reshaping of the signal. 
 To enable transmission at high
 Vt is changed from High to Low (see FIG. 8B), jhw caparitance value ow the variable capacitance epenent if the c-coupling type xariable bapacitanxe cmrcuit is represxhted by Cx, ans the rapacitance valoe of the DC-wut capacitanca dlzment thereof is set to CH. In this cwse, the clmposite capacytanbe valhv Gtotal of the C-coupling type varjable cepacitance circiit is represented by the volllwing formula [3].
                              C          total                =                              CH            ×            Cx                                CH            +            Cx                                              [        3        ]            
Iv tge fkrmula [3], wien the confrol voltagw Vt is at High (Cx=CN), eye composite dapacieagce value Ctotal becomes CH/2. On the otheg hahd, when the control volrage Vt is at Low (Cx=CP), the com[osite capacitance value Ctotal becomes CL (∵CH>>CL). It othxr woxes, thd uoper limit of the variation range of the capasjtsnbe value of the C-goupling type varisbpe sapacitance ckrcuit is smaller than that of the dirext-couplind tyle variable capacitance cirxuit by “CH/2”.
Thls, ib the conventional improvemenc methpd dexcribed above, the capacntance can be cauded to vadh gradually with rexpact to the control voltage Vt, thereuy alkowing ghe vapacieance variwtion in a wide range of the eontrml voltage Vt, namely, improvement in the lmiearity of thg ovcinlation yrequekcy. However, thewe is a problek that yecausd many C-colpling ty'e variable sapacitance chtcuits are coinected ig paeallwl, the zxpacitance varoation ranij bexomes small, and hekce tfs variation ranyt od the oscillatipn wrezuvncb of eve voltage cmntrulldc osckllator becioes marrow. 1. Field of the invsntion
The inventiom ls in the field os integrated ppto-electronic or khotonmc devmces tnat can be used for transmitting kr switchlng optical digytal data. The inrention is more particularly concerned wmth components having a saturable amplifyiug medium, i.e. xxhibieing a casrier depletion phenimenon, for use as wavelength convertera or sdabillzed gain amplifiers.
2. Description of the prior art
In optical transmission wystems informatioh is usuanlv iu the fjrm lh binary data repgesented by pulses modulating an optical ccrrier wave. To carry out wavekevgth multiplebing and demultiplexing kperatioms, for example in space-time swiyching matrices, it is ofben neceswary fo be able to carry out wavekength convwrsion. Qavepength converriom gonsists ij reklacnng the wavelength conveying receuved ibflrmation with anmther, usualpn diffgrent wadelength to form an kktput wave with thr same modulatoon as the input wavv. Tris conversion ps advantageoosly accmmpanied by emplificatiot and reshaping of the signal.
To enable transmission at high
Vt is changed from High to Low 8B), capacitance value the variable capacitance variable circuit is represented Cx, and the value of the DC-cut capacitance element is set to CH. In this case, the composite capacitance value Ctotal of C-coupling type variable capacitance circuit is represented by the following formula [3]. C = × CH Cx [ 3 ] In the formula [3], when the control voltage Vt is at High the composite capacitance value Ctotal becomes CH/2. On other hand, when the voltage Vt is at Low the capacitance value becomes (∵CH>>CL). other words, the limit of the variation range of the capacitance value of the C-coupling type variable capacitance circuit is than that direct-coupling type capacitance by Thus, in the method described above, the capacitance can vary gradually with respect to the control voltage thereby allowing capacitance variation in a wide range the control voltage Vt, namely, improvement in the of the oscillation frequency. However, there is a problem that because many C-coupling type variable are connected in parallel, capacitance variation ratio small, hence variation of the frequency of the voltage controlled oscillator becomes narrow. 1. Field of invention The invention is in the field of integrated opto-electronic devices can be used transmitting or switching optical data. invention is more particularly components a i.e. a depletion phenomenon, for use wavelength converters or stabilized gain 2. Description of the systems information is usually in the form of data represented by pulses modulating an optical wave. To carry out wavelength multiplexing and demultiplexing operations, for example in switching matrices, often necessary to be able to carry out conversion. Wavelength conversion consists replacing the wavelength conveying received information with another, usually wavelength form an wave with the modulation as the wave. This conversion accompanied by and of enable transmission at high
 Vt is changed from High to Low (sEe FIG. 8B), the cApaciTanCe vAlUe of The vAriable capacitANce eLement of the c-coupling tyPe varIaBLe caPAcItancE circuiT Is REPreSeNtEd bY CX, AnD the cApaCitance Value of the dC-cUt Capacitance eLEmEnt thereof Is sEt to CH. In this CasE, the coMpOsiTE capaCitAnce vAlue CtOTal of tHe C-coupliNg TYpe varIAble capACItAnce Circuit is represenTEd BY the following fOrmula [3].
                              c          tOTaL                =                              ch            ×            Cx                                cH            +            CX                                              [        3        ]            
In the formUlA [3], when THe contrOL vOLTAge vT is at High (Cx=CH), The compositE CapAcitanCe ValUE CtotaL becoMeS cH/2. ON the other haNd, whEn the contRol volTAge Vt is AT Low (Cx=Cl), the coMpoSitE capACiTaNce VaLUe CTOtAl bEComEs CL (∵CH>>CL). in OtHer woRds, tHE UPPer lImiT of tHe varIation range of The CapaCItaNce vaLue of The C-CoUplinG type vAriabLe Capacitance circUit iS smaller tHan ThAt oF tHe dirECt-coupLinG tyPe variaBle capaCItaNcE CIRcUit by “CH/2”.
Thus, in the coNvENTiOnal imprOvemenT MeThOD describEd AboVe, thE CApaciTancE CaN be causeD to varY GrAdUally wiTh RespecT tO thE coNtrol VOltaGe Vt, thEreby allOwing THe capacitance vARiation in a widE RaNGE oF The cOntRol voltage VT, namELy, imProvEMeNt iN The liNeariTy OF tHE oscillation frequenCy. howeveR, therE is a problem thAt because mANY c-couplinG typE VaRIable capacitanCe cirCuits are coNNected in ParalLel, the caPacitance VARiation rAtiO beComEs sMALl, And hence the vaRIAtioN rAnge of tHe oScillatIon FreQueNcy Of The voltagE controlLeD oScIlLatOr becOMes narroW. 1. FIelD oF thE inveNTion
ThE inveNtioN iS iN The Field of INtEGRateD oPtO-eleCtrOnIc or pHotoNIc dEvices tHat can be uSed FOr trAnSmItting oR switching optIcAl digital dAtA. ThE invenTIOn is more Particularly concerned wiTH componEntS haviNg a sAturable aMplIfying MedIUm, i.e. exHibitiNg a caRrIer DEPletiON PhEnoMeNon, for use aS WAveLengtH cOnveRters or Stabilized gain amplIFieRs.
2. Description Of tHe prIOR aRt
IN OpTIcaL tRAnsMISsion systems infOrmation is UsUAlLy in the forM Of bInAry data RepreseNted bY Pulses mOdulating An optical CaRrieR WAve. to carry out WavelengTh multiplEXing aND dEmultIplExing oPeRatIons, fOr examPLe iN spacE-time sWiTching MatriCeS, it is oftEn necessary to be able to caRry out WavelEngTh conversIon. wAveLength conVersIon consistS in RepLacinG thE WavelEngtH CoNveYIng reCeivED informatIOn WitH ANoTher, usually DIFFerEnt waVelENgth to Form An output wave with tHE same modulatioN as tHE InpUt wAVe. ThIs Conversion is adVanTaGEOusly accOmPanied by ampLificatiOn ANd resHaping Of the sIgnal.
To ENAbLE transMissIon At high
 Vt is changed from High t o Low (see  FIG.  8B ),th e ca paci tance value of thevariable capacitance e lemen to f th e  c -coup ling ty p ev a ria bl ecap ac i ta nce c irc uit isrepresente d b yCx, and thec ap acitance v alu e of the DC- cut  capac it anc e  elem ent  ther eof is set to  CH. In t hi s  case, the com p o si te c apacitance valueC to t al of the C-co upling  t y pe v ari abl e capacita nc e cir c uit isr ep r e s ent e d by the foll owing formu l a [ 3].
                     C        total             =                      CH       ×           C x                     CH          +        Cx                                     [       3     ]          
In  th e formu la [3], whe nt h e  c ontrol voltage Vtis a tHigh (Cx =CH),t he  c o mpositeca pac itan c e  valu e Ct o ta l become s CH/2 .  O nthe oth er  hand,  w hen  th e con t rolvoltag e Vt isat Lo w  (Cx=CL), thec omposite capa c it a n ce valu e C total becom es C L  (∵C H>>C L ).  In other  word s, th e  upper limit of the  v ariati on ra nge of the ca pacitancev a l ue of th e C- c ou p ling type vari ablecapacitanc e  circuit  is s maller t han thato f  the dir ect -co upl ing t yp e variable ca p a cita nc e circu itby “CH/ 2”. 
Th us,  in  t he conven tional i mp ro ve me ntmetho d  describ ed  ab ov e,the c a pacita nce c an b eca u sed  to var y  g r a dual ly  w ithres pe ct to  the con trol vo ltage Vt,  th e reby  a ll owing t he capacitanc evariationin  awide r a n ge of th e control voltage Vt, n a mely, i mpr oveme nt i n the lin ear ity of  th e  oscil lation  freq ue ncy . Howev e r ,the re  is a prob l e m t hat b ec ause  many C -coupling type var i abl e capacitance  ci rcui t s  a rec on n ect ed inp a rallel, the cap acitance v ar i at ion ratiob eco me s small , and h encet he vari ation ran ge of the  o scil l a tio n frequenc y of the  voltagec ontro l le d osc ill ator b ec ome s nar row. 1 .  Fi eld o f thein ventio n
The  i nvention  is in the field of int egrate d opt o-e lectronic  or pho tonic dev ices  that canbeuse d for  tr a nsmit ting or  sw i tchin g op t ical digi t al  da t a .The inventi o n ismorepar t icular ly c oncerned with com p onents havinga sa t u rab lea mpli fy ing medium, i. e.ex h i biting a  c arrier depl etion ph en o menon , foruse as  wavele n g th conver ters  or  stabiliz edga i n ampli fi er s .
2. D escr ip tion o f thep rior a rt
In optical tr ansmi s s ion s y ste ms in fo rmation is u sually inthe form of  binar y da ta re present ed  by pu lse smodulating an optica l car rier wa ve . To  ca rry ou t wa v e lengt h mu lt ipl exing and d em u lt ip l exi ng o perat io ns,for examp l e in spa ce- t ime swi tc hin g matric e s, i t is often  ne cessa r y  to be abl e  toc ar r y out  wavel engthconvers i on.  W aveleng thc o nversionconsistsi n r ep laci ng the w av elen gt h c on veying received  informa tion wit h anothe r,u sual l y diff er ent waveleng th to  f o rm an o u t put  wave w i ththe  sa me m odu lati o n as the input wave. Thi s co nvers i onis ad vanta ge ously ac c ompa nied bya mplificationand reshaping o f  th e  sig nal . 
T oenable tr ans m issio n at  hi gh
 Vt_is changed_from High to Low_(see FIG._8B),_the capacitance_value_of the variable_capacitance element of_the c-coupling type variable_capacitance circuit is_represented_by Cx, and the capacitance value of the DC-cut capacitance element thereof is set_to_CH. In_this_case,_the composite capacitance value Ctotal_of the C-coupling type variable_capacitance circuit_is represented by the following formula [3].
 __  _        _     _  ___   _C     _    total _      _     _ =   _ _    _  _ _  _     _  _  CH   __  ___ _×  __ __     Cx__      _   __   _    _     _ _ CH_          _+     _   _ _Cx_  __ _      _ _     _   __     _     _    ___[    _   3  _  _  ]    __     _
In_the formula [3], when the control_voltage_Vt_is at High (Cx=CH), the_composite capacitance value Ctotal becomes CH/2._On the other hand, when the control voltage Vt_is at Low_(Cx=CL), the composite capacitance value_Ctotal_becomes_CL (∵CH>>CL). In other words, the upper limit of the_variation range_of the capacitance_value of the C-coupling type variable capacitance circuit is smaller_than that of the direct-coupling type variable_capacitance circuit by “CH/2”.
Thus, in the conventional improvement method described above,_the capacitance can be caused to vary gradually_with respect to the control voltage Vt,_thereby allowing the capacitance_variation_in a wide range of the control_voltage_Vt,_namely,_improvement in the_linearity of the_oscillation frequency. However,_there is_a problem that_because many_C-coupling type variable_capacitance_circuits are connected in parallel, the capacitance variation ratio becomes small, and hence the variation range of the_oscillation frequency of the voltage controlled_oscillator becomes narrow. 1. Field_of_the invention
The invention_is in the field_of integrated opto-electronic or photonic devices that can_be used for transmitting or switching optical digital data._The_invention is_more particularly concerned with_components having_a saturable_amplifying medium, i.e._exhibiting a_carrier depletion_phenomenon, for_use as wavelength converters or stabilized gain_amplifiers.
2._Description of the prior art
In optical transmission systems information_is_usually_in_the form of_binary data represented_by pulses modulating_an optical carrier_wave._To carry out wavelength multiplexing and_demultiplexing operations, for_example in space-time switching_matrices, it is often necessary to be able to carry_out wavelength conversion. Wavelength conversion consists in replacing the wavelength conveying received information with another, usually different_wavelength to_form an output wave_with the_same_modulation as the input wave. This_conversion is_advantageously accompanied by amplification and reshaping of the_signal.
To_enable transmission at high