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JOURNAL IEEE OF QUANTUM ELECTRONICS, VOL.343 QE-20, 1984 APRIL NO. 4, [ 121 N. Holonyak, Jr., R. M. Kolbas, W. D. Laidig, B. A. Vojak, K. Hess, R. D. Dupuis, and P. D. Dapkus, “Phonon-assisted recombination and stimulated emission in quantum-well A1,Gal-,AsGaAs heterostructures,” J. Appl. Phys., vol. 51, pp. 1328-1337, Mar. 1980. [ 131 A. Sugimura, “Phonon assisted gain coefficient in AlGaAs quantum well lasers,’’ Appl. Phys. Lett., vol. 43, Oct. 1983. [ 141 J. S. Blakemore, “Semiconducting and other major properties of gallium arsenide,” J. Appl. Phys., vol. 53, pp. R123-R181, Oct. 1982. [ 151 K. Itoh, M. Inoue, and I. Teramoto, “New heteroisolation stripegeometry visible-light-emitting lasers,” IEEE J. Quantum Electron., vol. QE-11, pp. 421-426, July 1975. [ 161 W. T. Tsang, “Device characteristics of (A1Ga)As multiquantumwell heterostructure lasers grown by molecular beam epitaxy,” Appl. Phys. Lett., vol. 38, pp. 204-207, Feb. 1981. [ 171 W. T. Tsang, “Extremely low threshold (A1Ga)As modified multiquantum well heterostructure lasers grown by molecular beam epitaxy,”Appl. Phys. Lett., vol. 39, pp. 786-788, Nov. 1981. [ 181 W. Streifer, D. R. Schifres, and R. D. Burnham, “Optical analysis of multiple-quantum-well lasers,” Appl. Opt., vol. 18, pp. 35473548, Nov. 1979. [ 191 H. C.. Casey, Jr. and M. B. Panish, Heterostructure Lasers. New York: Academic, 1978. Akira Sugimura was born in Osaka, Japan, on May 10, 1947. He received the B.S. degree in physics from Kyoto University, Kyoto, Japan, in1970,andthe M.S. and Ph.D. degrees in physics from the University of Tokyo, Tokyo, Japan, in 1972 and 1975,respectively. In1975hejoinedthe Musashino Electrical Communication Laboratory, Nippon Telegraph and Telephone Public Corporation, Tokyo, Japan. He hasbeen engaged in research on optical fibers and semiconductor lasers. Dr. Sugimura is a member of the Institute of Electronics and Communication Engineers of Japan, the Physical Society of Japan, and the Japan Society of Applied Physics. Quantum Phase Noise and Field Correlation in Single Frequency Semiconductor Laser Systems PHILIPPE B. GALLION, MEMBER, IEEE, AND GUY DEBARGE [19]. The phasenoise of a single frequencysemiconductor laser is aparameter ofmajorimportanceinapplicationsin which the temporal coherence properties of optical signals are involved. Suchapplicationsaretransmissionssystemsand sensorsinwhichphaseorfrequencymodulated signalsare detected by heterodyne or homodyne techniques [27]-[31] or discriminated by direct interferometric detection[32], [ 3 3 ] . The laser phase is also a determining parameter for incoherent systems in which a spurious coherent mixing produces a phase to intensity noise conversion: this is for example a case for the square law detection of a beam which is first split by a polarINTRODUCTION ization dispersive medium,andtheonepartis,latermixed HE temporal coherence properties of multimode semicon- through polarization sensitive elements, with the another underductor lasers have been discussed by a number of authors going a time delay [21] . The repercussion of spectral spread on such systems can be [ 1] -[SI . Experimental investigations of these properties were completely discussed in terms of the autocorrelation function commonly achieved by using interferometric or beating techand spectral density of the photocurrent; the purpose of this niques [9] - [ 11] . The higher temporal coherence of single lonpaper is to give a simple unified treatment which can be applied gitudinalmodesemiconductor lasers hasalsobeendiscussed in the various above mentioned particular cases. The results are [ 3 ], [ 121- [ 141 and experimentally investigated by the above discussed as a function of the laser linewidth, phase matching, mentioned methods [ I 51 -[26]. For a single-frequency conthe balance and the phase correlation between the two mixed stant-amplitude laser source operating for above threshold, the beams. In addition the phase noise sensitivity of various detecrandom quantum phase fluctuations are usually considered to tion schemes is compared. be the major source of optical spectral spread [3], [ 121 , [ 171- Abstract-The influence of quantum phase fluctuations which affect single frequencysemiconductor lasers in various coherentdetection systems is discussed in terms of photocurrent autocorrelation and spectral density functions. The general treatment given in this paper can be applied in diverse practical cases and points out the problems of phase correlation and phase matching between the two mixed optical beams. In the more general case the Photocurrent spectrum is found to be composed of discrete and quasi-Lorentzian parts whose energies and spectral spreads are discussed as a function of the laser line width, the phase matching and the phase correlation between the two coherently combined fields. T QUANTUMPHASE NOISE MODEL FORSINGLE Manuscript received July 18, 1983;revised November 14,1983. LONGITUDINAL MODE SEMICONDUCTQR LASERS The authors are with Groupe Opto6lectronique Microondes et D6parteThe optical field emitted far above threshold by a single biased mentElectroniqueet Physique Ecole NationaleSuperieure des T616frequency laser is commonly modeledas a quasimonochromatic communications 46, rue Barrault 75634 Paris, Cedex 13 France. 0018-9197/84/0400-0343$01 .OO 0 1984 IEEE JOURNAL IEEE 344 OF QUANTUM ELECTRONICS, VOL. QE-20, NO. 4, APRIL 1984 amplitude-stabilized field undergoing a phase fluctuation [ 121 (1 1 a t ) = E , exp i[w,t + @(Ol where w, is the average optical frequency and @ ( tis) a stochastic process representing the random phase fluctuation leading t o the broadening of the spectral line. The time dependence of E , on time t is an amplitude noise. Its contribution to the field spectrum can be neglected in spite of its large spectrum width because its integration power is much smaller than the phase noise one [12] . It is useful tointroducetheoptical field autocorrelation function defined as G$)(T) = ( E * ( t ) E ( t+ T ) ) = (exp [iA@(t, T)] ) exp ( j w , ~ ) (2) where A@(t,T ) is the phase jitter, i.e., the randomphase change between times t and t + T A@(t,T ) = @(t+ T ) - @(t). (3) Underthe above mentionedassumptions,the phase jitter A@(t,T ) is usually assumed to be a zero-mean stationary random Gaussian process with the associated probability density function being [ 151 -[34] (4) (A@*(T))is the mean-square phase jitter which is related to the instanteous angular frequency-fluctuation spectrum S$ (a) by [341 [TI explain the experimental values reported by Fleming and Mooradian [13] : where ug is the group velocity of the light in theactive medium, hu the lasing photon energy, nSp the spontaneous emission factor [3], am the loss of the mirror, Po the output power per facet and a the linewidth enhancement factor introduced by Henry [ 141 . Forchanneled-substrate-planar(CSP)-structure Ga A1 As devices FlemingandMooradian [ 131 have reportedexperimental values for the product 2 y Po of 2 7 X 110 X IO6 rad . s-l . mW. Recently authors [35]-[38] have discussed modified a model taking into account the relaxation resonance effect. A Lorentzianlineshapewithasecondordercorrection is then carried out. This correction is not taken into account in this study which refers only to the first order model (assuming a flat frequency-fluctuationspectrum leading toa rigorously Lorentzian line shape). TOTALDETECTEDFIELDMODELIZATION The purpose of this paper is to express the spectral density of the photocurrent produced by homodyne and heterodyne detection of two fields as a function of their linewidth, their relative weight and their remaining phase correlation. For this purpose we assume thatthedetectedtotal field E T ( t ) is a superposition of a laser field E ( t ) as expressed by equation (1) with a time-delayed and frequency-shifted image of itself: E T ( t )= E(t) + aE(t + 7 , ) exp j n t (1 1) where a is a real factor which accounts for the amplitude ratio between two mixed fields. For coherent optical communica(*@2(T))= 27 S@(W)dU. (5) tion systems inwhich a weak signal is detected with a powerful local oscillator we have a << 1. For a phase-modulated optical signal detection by the retardation method 1321, [33] a is Using the well known relation 1341 closely one. a can take any value in the case of noncoherent single-mode transmissions systems and unbalanced sensors and T ) ] ) = exp [ - + (AQ2(7))] (6 1 (exp [+jA@(t, when the modes coupling in a single-mode fiber with polarizatherefore the laser field correlation function is expressed as tion dispersion is involved [21] . o T , is the time-delay which also refers to the eventual reG$)(T) = exp [-+ ( A @ * ( T ) exp )] ( j w , ~ ) . ( 7 ) maining phase correlation between the two combined beams. The case considered here concerns quantum phase-fluctuation For coherent communication systems, 7, is the time delay in the optical local field generator [23], [27], [30]. For differaffectingafar above threshold biased semiconductorlaser: then the instantaneous angular frequency-fluctuation spectrum ential phase shiftkeyingsystemsandforphase-modulated optical detection by the retardation method [32], [33]T , is a S,(w) can be assumed to be flat [12]-[16] leading tothe mean-square phase-jitter (AG2(7)) increasing linearly with the bit duration. Finally T , is the optical time delay for unbalanced interferometric systems and the dispersion time for the polaritime delay zation-dispersed modes in single mode fiber mixing [21]. The = 2y 17-1 (81 optical mixing of two fields ofequal linewidth and uncorrelated where 2yis the angular full linewidth athalf maximum (FWHM) phases is obtained by T , = 00. n is themeanfrequencydifferencebetweentwomixed of the Lorentzian laser field spectrum S E ( w ) obtained by the fields. a is theintermediaryfrequency in heterodynecomFourier transform of (7) munication systems and the acousto-optic frequency in hetero717 dyne sensors. 52 = 0 for homodyne communications systems, s, (w) = E; y 2 + (w - w,)2 . for fiber interferometers without Bragg-cell, for the polarization dispersed modes in single mode fiber mixing and for the 2y is given by the Schawlow-Townes formula including the phase modulated optical detection by retardation method. With linebroadening excess factorintroducedbyHenry[14]to ?' 1; wr sin - GALLION AND DEBARGE: FREQUENCY SINGLE SEMICONDUCTOR LASER SYSTEMS 345 appropriate values of CY,7, and C2 (1) for the total detected field one can easily consider the above mentioned four cases. Because of the square law of optical detectors, these interferometric systems are able to convert the quantumphase noise of the laser field E(t) into intensity noise and then give a spectral spread of photocurrent I(t). For stationary fields, the autocorrelation function RZ(7)of the photocurrent depends only on the intensity correlation function of the detected total field G,g(r) PI ~ ~ (=7eo)G$;(o) s ( T ) +02 G$$) (I2) (1 6 ) For laser phase noise A@2( T ) is given by (8), using the reduced timedelay,defined a s 7 = 277 andnotingby 0 the meanphase G ( 2 ) ( ~ex) difference W,T, betweenthetwomixedfields where e is the electron charge, u is the detector sensitivity, & ( T ) is the Dirac function, Gz'(7) is the firstorderopticalintensitycorrelation function, [(I t c u 2 ) t 2a cos e exp G g (7) - ___ - E: (-3 1 ET 2 2 for any7 4a2 exp (-7,) {sin h ( 1 ~ 1 -7,) cos2 e [ I - exp ((1 i 771 1 -7,)J} i.e., the second order optical field correlation function defined for 0 <T<T,. hv (1 7 ) -.' By virtue of the Wiener-Khintchine theorem, the spectrum (13) ofthephotocurrent is given by theFouriertransform of its autocorrelationfunction.Omittingtheshot noise termand where the brackets denote a timeaverage. 'using the reduced angular frequency, defined as0 = (3/2y,the Thefirsttermin (1 2 ) is the usualshot-noiseassociatedwith 'two-sided spectrum is written as the dc componentof the photocurrent and the second account 2 forthisdccomponentandfluctuations arising from phase into SZ((J) = t a2 t 2cu cos e exp intensity noise conversion. u2 E: G~;(T) = ( ~ ~ ( t ) ~ $ t( Tt ))E ~ * I~ C t (7(~) t) (3 [1 1 PHOTOCURRENT SPECTRUM IN THE HOMODYNE (S2 = 0) t 4cu2 exp (-7,) 1tw2 DETECTIONCASE The autocorrelation functionof the photocurrent is obtained sin 0 7, - by substituting (1 1) into(13) with s2 = 0. This substitutiongives rise to 16 terms. Using (1) for the laser field after a straight-for(1 8) (2) only as a function ward calculation allow us to express GET(^) where 6(G) is the delta function. of the phase jitter of linear combinationof @ ( t )and @(tt 7): Let us consider one of particular cases in which a two beams interferometer with equal optical field intensities is tuned up G$:(T) =E," ((1 t cu212 t 2a(1 t a 2 )expjw,T, for a maximum optical power output. Therefore we have CY = . (exp jA@(tt T , 7,)) t CC t a2 exp 2jw,7, 1 and 0 = 2 k l with k integer. Taking moreover the Gaussian probability density function assumption for the phase jitter (4), * (expjA\k(t, io)> t CC t a2 one can find the following expression derivedby Armstrong (exp jA(a(t,7 , ) ) + CC) (14) 1151 w7, (J 1 and CC denotes the complex conjugate of the preceding term. The approximately Lorentzian part of this spectrum is plotted $ ' :() ' can be expressed Only as a function Of by in Fig. l(a) and l(b) for variousvaluesof the parameters%, i.e., using (6) and coherence ratio, time todelay timethe 0 = (J,T,,the i.e., mean phase difference between the two mixed beams. (1 t a 2 ) 2t 4a(l t a2)cos (o,T,) PHOTOCURRENT SPECTRUM IN THE HETERODYNE (C2 # 0) DETECTIONCASE In this paragraph we perform a quite similaranalysis as in (1 1) into (13) give the previous chapter. The substitution of IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. QE-20, NO. 4, APRIL 1984 346 T i n dolq e0 .0 tir ratio T i n dolay tu t i n rut10 1 2. .e 1. cc.S-3 2 ca2=.5 2 .7 ca2=.s 9. cns2-l .e m Y r €LETECTICN KnmYE mocTIW .5 -4 .9 .2 .I n WuTmH 1 ff--7 .0 t i n &lo T i n d o l q tu cohrrcnoP t i n rotlo 0 8 0 4 .e 1. codd 2 cLaz-.S 1. cc.S-3 2 cLaz-.5 3. -1 s. .7 -1 ~ 1 .8 ! K W D Y I E DETEclIW I 1 .5 I I I .4 1 -T ----!- -- .3 I .2 .1 - 0 0 2 9 4 s RrmxEDRIolLDEy o 1 2 9 EL.lm3 FFf!x€N3 4 5 (b) Fig. 1. Lorentzian part of the homodyne spectrum as a function (a) and (b) of the time delay to coherence time ratio To and of the phase matching parameter cos2 e. also rise to 16 termsbut because anexplicittimedependencz G$;(T) =E," { ( l + 01~)'+ o2 exp (~RT) appearing in the form of exp + j R t , 10 of them average out to . (exp jA@((t,7 , ) ) + CC) 0 ; using the previous notations, the 6 surviving terms give the where @ ( t )have the same meaning as above (1 5). following result [22] - [ 2 3 ] : AND GALLION DEBARGE: FREQUENCY SINGLE SEMICONDUCTOR LASER SYSTEMS 347 et ( T o e )= 2a2 [ 1 - exp (-T~)] [1 t sin’ Using again the (6) G$;(T) is written c €,(Toe) = 1 t a2 t 2a cos e exp (21) In the same manner as the previous chapter., using the same reduced variables one obtains the first order optical intensity correlation function G$;(T): 2a2 * cos E T exp (-T), + Omitting again the usual shot noise term, the two-sided heterodyne photocurrent spectrum is then obtained by Fourier transform e exp (-7,)] (24) (-3 1 ’. (251 For an in phase (e = 0) and an out of phase (8 = 7 ) optical mixing, the eL (To, e ) arrives at a minimum value. On the other hand in the case of a quadrature optical mixing, according to the well known fact that the phase noise conversion efficiency e ),arrives at a maximum value. is optimum, the eL ( T ~ The heterodyne case is quite different. Here the photocurrent spectrum consists of a dc component, a monochromatlc and an approximately Lorentzian component centered at the intermediary frequency G. The first of them refers to the dc current associated with the noninteractive superposition of the two optical powers. The monochromatic one at the frequency 2 ! expresses the remaining phase correlation between the two mixedbeams.Thethirdandlastterm is quasi-Lorentzian spectrum which cancels out for To = 0 and become rigorouslyLorentzian with linewidth twice than the laser spectrum when - 7 , = 00. t a’ exp (-7,) 1 1ITT +(a-2 ) 2 1 sin ( T S - i 7 ) ~ ~ - cos (W- 2 ) T o w - 2 . The approximately Lorentzian part of this spectrumis plotted i.e., the time in Fig. 2 for various values of the parameter 7,) delay to coherence time ratio. Because of the mean frequency difference between the twomixed beams the photocurrent spectrumis no longer dependent on the phase matching even in the correlated case. It is to be noticed that because of time averaging of phase matching in the heterodyne case the photocurrent spectrum is founded to be the same as in the homodyne case, with cos2 0 = The energiesin thequasi-Lorentzianpart E ~ , ~ ( T and , ) in , ) the spectrum are given the monochromatic part E ~ , ~ ( Tof by eL, n(~,) = 201’ [ 1 - exp (-7,)] (26) i. eg, = 2a2 exp (-7,). (27) These energies expressions stand for an uniform transfer of energy from the monochromatic to the Lorentzian component DISCUSSION when increasing the decorrelation time7,. The homodyne spectrum consists of two terms whose behavAs show in Fig. 3 there is no significant difference in the corior relates closely to T , and 0 values. Let us examine the phys- related spectral spread in the homodyne and heterodynecases. ical meaning of eachterminseveraltypicalcases.Thefirst Some comparison of these results with experimental measureterm which is a dc component refers to the simple adding of ments has been made in various particular cases: Heterodyne the two optical powers and to the amount of remaining phase detection of beams with uncorrelated phases [20], heterodyne correlation between the two mixed beams. For large values of detectionofbeamswithcorrelatedphases [23]-[24] and the normalized time-delay T,,i.e., for completely decorrelated homodyne detection of beams with correlated phase and phase 0 vanishes. On quadrature [21]. Theresultsindicateforeach fields: its dependence on the phase matching case that the the other hand for a value of T , close to zero it becomes very used theoretical description of the laser-phase random process sensitive on the 0 value and it depends no longer on the spectral is consistentwithexperiments.Experimentalmeasurements spread. The second term takes the form of an approximately in the moregeneral case would be of a great interest. Lorentzian lineshape which vanishes out for a close to zero7, the optical value. For large values of T, this term stands for CONCLUSION mixingof two independent fields and it becomes rigorously Lorentzian with a FWHM which is twice the original laser lineTherepercussionofquantum laser phasenoise in various as anopticalproductwidth. Id thiscase thedetectoracts coherent systems has been discussed in terms of autocorreladetector whose output is the autocorrelation product of the tion function and spectral density of the photocurrent. The laser field spectrum. The spectrum is then no longer dependent given treatment includes the phase matching, the balance and on the phase matching8 . the phase correlation between two coherently combined beams. The etlergies ofthequasi-Lorentziancomponent eL (7,B) For stronglycorrelatedbeamsthephotocurrentspectrum is and of the dc component eg (‘roe) of the spectrum are given found to be a Dirac function both in the homodyne and the heterodyne cases, and extremely dependent on phase matching by 348 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. QE-20, NO. 4, APRIL 1984 NORMALIZED LGRENZIAN PARTOF PHOTOCURRENT SPECTRUM 1 I au= 8 - I Time delay to’coherence is t a u tlme ratio For any t h e t a .6 HETERODYNE OETECTION .5 .4 .3 .2 .l 0 0 1 2 3 4 5 NORHALIZED DEPARTURE FROM INTERMEDIATE F E O U E N C Y Fig. 2. Lorentzian part of the heterodyne spectrumas a function of the time delay to coherence time ratio F ~ . NORMALIZED HALF LINEWIOTH OF THE PHOTOCURRENT SPECTRUM 8 ~~ ~ ~~ ~ ~ ~~~~ Heterodyne case 7 ~ 2 - , Homodyne caee I 6 1 Cos2=0 5 4 3 2 1 TIHE DELAY TO CGMRENCE TIMERATIO Pig. 3. Normalized half linewidth at half maximum of the Lorentzian partof the photocurrent spectrum. in the liomodyne case. For weakly correlated beams the spec- photocurrent spectrum is a complex mixture of the two noises trum is Lorentzian with a FWHM which is twice the original and its derivation seems to be quite tedious. REFERENCES laser homodyne linewidth. the photocurrent in Then the case, spectrum depends no longer on the phase matching. The pres[ 11 J. A . Armstrong and A. W. Smith, “Intensity in GaAs laser emisent analysis has been limited to laser sources exhibiting phase sion,”Phys. Rev., vol. 140, pp. 155-164, 1965. noise Only. If the laser sources also exhibit intensity noise the [ 2 ] M. Ciftan and P.P. Debye, “On the parameters which affect the GALLION AND FREQUENCY DEBARGE: SINGLE SEMICONDUCTOR LASER SYSTEMS CW output of GaAs lasers,” Appl. Phys. Lett., vol. 6, pp. 120121,1965. [31 H. Haug and H. Haken, “Theory of noise in semiconductor laser emission,” 2. Phys., vol. 204, pp. 262-275,1967. of CW [41 D. E. McCumber, “Intensity fluctuations in the output laser oscillators,”Phys. Rev., vol. 141, pp. 306-322,1966. M. J. 0. Strutt, “Laser-light noise andcurrent [51 G.Guekosand noise of GaAsCw laser diodes,” IEEE J. Quantum Electron., vol. QE-6, pp. 423-428,1970. Y. A. Bykovskii, V. A. Elkhov and A. I. Larkin,” “Coherence of the radiation emitted by asemiconductor laser and its use in holography,”Sov. Phys. Semicon., vol. 4, pp. 819-821, 1970. [71 H. Jackel and H. Melchior, “Fundamental limits of thelight intensity fluctuations of semiconductors lasers with dielectric transverse mode confinement,” in Proc. Opt. Commun. Conf., Amsterdam, The Netherlands, 1979. A. Guttner, H. Welling,K. H. Gericke and W. Seifert, “Fine structure of the field autocorrelation function of a laser in the threshold region,” Phys. Rev., vol. A18, pp. 1157-1168, 1978. i91 A. R. Reisinger, C. D. David, Jr. K. L. Lawley and A. Yariv, “Coherence at a room-temperature CW GaAs/GaAlAs injection Laser,” IEEE J. QuantumElectron., vol. QE-15, vol. 12, pp. 1382-1387,1979. K. Petermann and E. Weidel, “Semiconductor laser noise in an interferometer system,” IEEE J. Quantum Electron., vol. QE17, pp. 1251-1256,1981. D. P. W. Chown; M. Spencer andR. E. Epworth, “Correlated laser spectral and intensity noise in short-path-difference interferometers,” IEE Proc., vol. 129, pp. 267-270, 1982. A. Yariv, Quantum Electronics, 2nd Ed. New York: Wiley, 1975. [ 131 M. W. Fleming and A. Mooradian, “Fundamental line broadening of single-mode (GaA1)As diode lasers,” Appl. Phys. Lett., vol. 3 8 , ~ 511-513,1981. ~ . [ 141 C. H. Henry, “Theory of the linewidth of semiconductors lasers,” IEEE J. Quantum Electron., vol. QE-18, pp. 259-264, 1982. [ 151 J. A. Armstrong, “Theory of interferometric analysis of laser phase noise,” “J. Opt. SOC.Am., vol. 56, pp. 1024-1031, 1966. [ 161 A. E. Seigman, B. Daino and K. R. Manes, “Preliminary measurements of laser short-term fluctuations,” IEEE J. Quantum Electron., vol. QE-3, pp. 180-189, 1967. [ 171 E. D. Hinkley and C. Fredd, “Direct observation of the Lorentzian as limited by quantum phase noise in a laser above threshold,” Phys. Rev. Lett., vol. 23, pp. 277-280, 1969. [ 181 H. Z. Cummins and H. L. Swinney, “Light beating spectroscopy,” in Progress in Optics, E. Wolf, Ed. Amsterdam,TheNetherlands: North-Holland, 1970. [ 191 A. Yariv and W. M. Caton, “Frequency, intensity and field fluctuations inlaser oscillators,” IEEEJ. QuantumElectron .,vol. QE-10, pp. 509-517,1974. [20] T. Okoshi, K. Kikuchi and A. Nakayama, “Novel method for high resolutionmeasurement of laser outputspectrum,” Electron. Lett., vol. 16, pp. 630-631, 1980. [21] Y. Yamamoto, T. Mukai and S . Saito, “Quantum phase noise and linewidth of a semiconductor laser,” Electron. Lett., vol. 17, pp. 327-329, 1981. [ 221 P. Gallion and F. J. Mendieta, “Incidence du bruit de phase sur la detection heterodyne de ‘signaux correlis,” in Proc. 3rd French Con$ Single Mode Fiber Transmissions, Marcoussis, France, 1981. [ 231 P. Gallion and F. J. Mendieta and R. Leconte, “Single-frequency laser phase-noise limitation in single-mode optical fiber coherent detection systems with correlated fields,” J. Opt. SOC. Am., vol. 72, pp. 1167-1170, 1982. [24] P. Gallion, F. J. Mendieta and C. Chabran, “Single mode laser spectral spread repercussion in single-mode optical fiber coherent detection systems,” in PYQC. European Con$ Opt. Syst. Appl., bdinburgh,Scotland,1982, also, Proc. SPIE, Washington, DC, 1983. [ 251 A. Dandridge and A. B. Tveten, “Phase noise of single mode diode lasers in interferometer Systems,” Appl. Pkys. Lett., vol. 39, pp. 530-532,1981. [ 261 P. Gallion, C. Abitbol and H. Nakajima, “Linewidth measurement 349 of a single modesemiconductor laser bysyntheticheterodyne interferometry,”in Proc. Opt. SOC. Am. Annu. Meet., New Orleans, LA, 1983. [27] Y. Yamamoto “Receiver performance evaluation ofvarious digital optical modulation-Demodulation systems in the 0.5-10 pm wavelength region,” IEEE J. Quantum Electron.,Fol. QE-16, pp. 1251-1259, 1980. [28] P. Gallion, M. Attia and F. J. Mendieta, “Experimental study of some fundamental properties of an optical heterodyne receiver,” in Proc. European Conf Opt. Syst. Appl., Utrecht, The Netherlands, 1980. [ 291 F. Favre, L. Jeunhomme, I. Joindot, M. Monerie and J. C. Simon, “Progress towards heterodyne-type single mode fiber communication systems,” fEEE J. Quantum Electron., vol. QE-17, pp. 897906, 1981. [30] T. Okoshi and K. Kikuchi “Heterodyne-type opticalfiber communications,” J. Opt: Commun., vol. 2, pp. 82-88, 1981. [31] Y. Yamamoto and T. Kimura, “Coherent optical fiber transmission systems,” IEEE J. Quantum Electron., vol. QE-17, pp. 919935,1981. [32] S . Saito,Y.Yamamotoand T. Kimura, “Semiconductor laser FSK modulationand optical direct discrimination detection,” Electron. Lett., vol. 18, pp. 468-470, 1982. 1331 M. Tateda, S . Seikai and N. Uchida:“Phase-modulatedoptical signal detection by retardation method,” IEEE J. Quantum Electron., V O ~ QE-19, . pp. 96-100, 1983. [ 341 H. E. Rowe, SignalandNoisein CommunicationSystems. Princeton, NJ: Van Nostrand, 1965. [35] B. Daino, P. Spano, M. Tamburrini and S . Piazzolla, “Phase noise and spectral line shape in semiconductor lasers,” IEEE J. Quantum Electron.,vol. QE-19, pp. 266-270, 1983. [36] K. Vahala, C. Harder and A. Yariv, “Observation of relaxation resonance effects in the field spectrum of semiconductor lasers,” A p p l . Phys. Lett., vol. 42, pp. 211-213, 1983. [37] Y. Yamamoto, “AM and FM quantum noise insemiconductor . lasers-Part I:Theorical analysis,” IEEE J. Quantum Electron., VO~ QE-19, . pp. 34-46, 1983. [38] -, “AM and FM quantum noise in semiconductor lasers-Part 2: Comparison of theorical and experimental results for AlGaAs lasers,” IEEE J. Quantum Electron., vol. QE-19, pp. 47-58, 1983.