Traveling wave photodetectors (TWPD) have shown high-speed and highefficiency performance [1,2]. By distributing the RC elements and matching the microwave and optical velocities the RC time constant is no longer the bandwidth-limiting factor. Moreover, the trade-off between efficiency and bandwidth, inevitable for conventional vertical photodetectors, can be eliminated. Low-temperature-grown (LTG) GaAs material has been widely utilized for high speed photodetectors [3,4]. The detector bandwidth can easily be improved due to the short carrier life time of the LTG-GaAs material. For such detectors the impulse response is no longer limited by the carrier transit time but by the much shorter carrier recombination time. In this work, we incorporated a LTG-GaAs absorption layer in a p-i-n traveling wave photodetector (TWPD). The device was successfully fabricated and our results show that the performance can be enhanced by taking advantage of both the short carrier lifetime of LTG-GaAs and the high bandwidth efficiency product of a TWPD. Figure 1 shows the structure of the device (top) and the cross section of waveguide (bottom). The layers (bottom of fig. 1) were grown in a MBE system. The LTG-GaAs absorption layer (170 nm) was grown at 215 "C, and the substrate was subsequently insitu annealed at 590 "C for 10 minutes. The nand players were deposited at 570 "C. The device fabrication followed standard p-i-n photodetector processing [ 11. A polyimide layer was spun on the detector for passivation. Coplanar waveguide (CPW) metalization was used for connection to the nand pcontacts. The electrical impulse response was measured by pump-probe electro-optic (EO) sampling. For the optical excitation we used 100 fs pulses from a modelocked Tisapphire laser operating at 800 nm. After edge-coupling into the optical waveguide, the photocurrent is generated by exciting photocarriers in the LTG GaAs layer. A small LiTaO, crystal was placed on top of the CPW lines to probe the time evolution of the signal. As shown in fig. 2, the FWHM of the measured impulse response is 570 fs, corresponding to a -3dB bandwidth of 520 GHz. A external D.C. quantum efficiency of 8% was measured. Simulations have been performed to further study the device performance. The distributed photocurrent is excited by the optical wave propagating along in the p-i-n region [ 5 ] . At the output of the photodetector, the electrical wave is collected. There are three factors that will effect the impulse response. The fast carrier recombination in the LTGaAs, the velocity mismatch between optical and electrical waves, and the microwave loss
{"title":"Subpicosecond (570 fs) Response Of p-i-n Traveling Wave Photodetector Using Low-temperature -grown","authors":"Y. Chiu, S. Fleischer, J. Bowers","doi":"10.1109/MWP.1997.740286","DOIUrl":"https://doi.org/10.1109/MWP.1997.740286","url":null,"abstract":"Traveling wave photodetectors (TWPD) have shown high-speed and highefficiency performance [1,2]. By distributing the RC elements and matching the microwave and optical velocities the RC time constant is no longer the bandwidth-limiting factor. Moreover, the trade-off between efficiency and bandwidth, inevitable for conventional vertical photodetectors, can be eliminated. Low-temperature-grown (LTG) GaAs material has been widely utilized for high speed photodetectors [3,4]. The detector bandwidth can easily be improved due to the short carrier life time of the LTG-GaAs material. For such detectors the impulse response is no longer limited by the carrier transit time but by the much shorter carrier recombination time. In this work, we incorporated a LTG-GaAs absorption layer in a p-i-n traveling wave photodetector (TWPD). The device was successfully fabricated and our results show that the performance can be enhanced by taking advantage of both the short carrier lifetime of LTG-GaAs and the high bandwidth efficiency product of a TWPD. Figure 1 shows the structure of the device (top) and the cross section of waveguide (bottom). The layers (bottom of fig. 1) were grown in a MBE system. The LTG-GaAs absorption layer (170 nm) was grown at 215 \"C, and the substrate was subsequently insitu annealed at 590 \"C for 10 minutes. The nand players were deposited at 570 \"C. The device fabrication followed standard p-i-n photodetector processing [ 11. A polyimide layer was spun on the detector for passivation. Coplanar waveguide (CPW) metalization was used for connection to the nand pcontacts. The electrical impulse response was measured by pump-probe electro-optic (EO) sampling. For the optical excitation we used 100 fs pulses from a modelocked Tisapphire laser operating at 800 nm. After edge-coupling into the optical waveguide, the photocurrent is generated by exciting photocarriers in the LTG GaAs layer. A small LiTaO, crystal was placed on top of the CPW lines to probe the time evolution of the signal. As shown in fig. 2, the FWHM of the measured impulse response is 570 fs, corresponding to a -3dB bandwidth of 520 GHz. A external D.C. quantum efficiency of 8% was measured. Simulations have been performed to further study the device performance. The distributed photocurrent is excited by the optical wave propagating along in the p-i-n region [ 5 ] . At the output of the photodetector, the electrical wave is collected. There are three factors that will effect the impulse response. The fast carrier recombination in the LTGaAs, the velocity mismatch between optical and electrical waves, and the microwave loss","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"265 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116241396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Full-duplex Fiber-wireless System Using Electrical And Optical SSB Modulation For Efficient Broadband Millimeter-Wave Transport","authors":"G.H. Smith, D. Novak","doi":"10.1109/MWP.1997.740267","DOIUrl":"https://doi.org/10.1109/MWP.1997.740267","url":null,"abstract":"","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122374698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The difference frequency of two lasers is stabilised by an optical discriminator to provide a low noise source programmable from 27 to 40 GHz. A novel phase noise measurement technique is described using the optical discriminator itself. Introduction A paper' was presented at the 1996 lntemational Topical Meeting on Microwave Photonics which described a microwave source consisting of two lasers having their difference frequency stabilised by an optical discriminator. Measurements of phase noise, for an output frequency of GOOMHz, were included in that paper to demonstrate the phase noise improvement which could be obtained with the optical discriminator. The paper postulated that the phase noise spectrum is independent of output frequency and results confirming this were presented orally at the above meeting. This can be seen from the two laser signals: E1 = exp(jolt + a) (1 1 E2 = exp(jo2t + p) (2) The phase perturbations a and p give rise to phase noise sidebands. When the laser signals are combined and the difference frequency, (01 o2), is recovered using an optical detector, a and p will appear on the detector output, irrespective of the value of the difference frequency. This contrasts with quartz crystal derived microwave sources where the level of phase fluctuations and the concomitant sidebands rises rapidly with the order of frequency multiplication. The orally reported results extended to 20GHz, at which frequency the phase noise performance of the laser source was essentially the same as a Hewlett Packard 83711A Frequency Synthesiser. However these measurements were so close to the measurement floor of the instrumentation that they could not be regarded as absolute and simply confirmed the equivalence of the laser source to a high quality synthesiser. This problem is exacerbated at higher frequencies and a new measurement technique has therefore been devised and is described below. A two laser microwave source is now described which covers the frequency range of 27 to 40GHz, The actual frequency range evaluated being defined by the microwave components used in this particular experimental configuration and not the optics. The original phase noise measurements' were made using a Hewlett Packard 8565E Spectrum Analyser with an 85671A Phase Noise Measurement Utility. As this was unsuitable for measurements at frequencies up to 40GHz an alternative approach was used. Since the optical discriminator provides a reference for reducing phase noise sidebands it also provides a very convenient means for the measurement of these components. These appear at the discriminator output as the demodulated FM noise spectrum which can be readily converted to the phase noise spectrum of the two laser microwave source. This technique has the added advantage of yielding much higher sensitivities than the spectrum analyser approach. This has allowed much more accurate measurements to be made at offset frequencies above 1 OKHz, where the measurement sensitivi
{"title":"A Discriminator Controlled Broad-band Optical Microwave Source","authors":"M. Lewis, P. Sample","doi":"10.1109/MWP.1997.740231","DOIUrl":"https://doi.org/10.1109/MWP.1997.740231","url":null,"abstract":"The difference frequency of two lasers is stabilised by an optical discriminator to provide a low noise source programmable from 27 to 40 GHz. A novel phase noise measurement technique is described using the optical discriminator itself. Introduction A paper' was presented at the 1996 lntemational Topical Meeting on Microwave Photonics which described a microwave source consisting of two lasers having their difference frequency stabilised by an optical discriminator. Measurements of phase noise, for an output frequency of GOOMHz, were included in that paper to demonstrate the phase noise improvement which could be obtained with the optical discriminator. The paper postulated that the phase noise spectrum is independent of output frequency and results confirming this were presented orally at the above meeting. This can be seen from the two laser signals: E1 = exp(jolt + a) (1 1 E2 = exp(jo2t + p) (2) The phase perturbations a and p give rise to phase noise sidebands. When the laser signals are combined and the difference frequency, (01 o2), is recovered using an optical detector, a and p will appear on the detector output, irrespective of the value of the difference frequency. This contrasts with quartz crystal derived microwave sources where the level of phase fluctuations and the concomitant sidebands rises rapidly with the order of frequency multiplication. The orally reported results extended to 20GHz, at which frequency the phase noise performance of the laser source was essentially the same as a Hewlett Packard 83711A Frequency Synthesiser. However these measurements were so close to the measurement floor of the instrumentation that they could not be regarded as absolute and simply confirmed the equivalence of the laser source to a high quality synthesiser. This problem is exacerbated at higher frequencies and a new measurement technique has therefore been devised and is described below. A two laser microwave source is now described which covers the frequency range of 27 to 40GHz, The actual frequency range evaluated being defined by the microwave components used in this particular experimental configuration and not the optics. The original phase noise measurements' were made using a Hewlett Packard 8565E Spectrum Analyser with an 85671A Phase Noise Measurement Utility. As this was unsuitable for measurements at frequencies up to 40GHz an alternative approach was used. Since the optical discriminator provides a reference for reducing phase noise sidebands it also provides a very convenient means for the measurement of these components. These appear at the discriminator output as the demodulated FM noise spectrum which can be readily converted to the phase noise spectrum of the two laser microwave source. This technique has the added advantage of yielding much higher sensitivities than the spectrum analyser approach. This has allowed much more accurate measurements to be made at offset frequencies above 1 OKHz, where the measurement sensitivi","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124071777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
and to use higher carrier frequencies and their wide frequency bandwidth under the trend of multimedia expansion of mobile radio, called mobile computing and mobile video services. These micro/pico cellular technologies will pose the following new problems: (1) many radio base stations for wide area service; (2) a long implementation time and a large investment for future new service; (3) excess base station equipment due to increasing traffic peak factor. To solve the above problems, radio highway network has been proposed [ 13. This network consists of Fiber and Radio Extension Link (FREx Link) [2] [3], so called microwave-over-fiber link and photonic switching routing nodes. (Fig. 1) In the network, radio signals transmitted by the radio terminals are encapsulated into optical signal and transferred to the appropriate remote radio control station via several optical routing nodes with their radio signal format kept. Consequently, the system can open the radio free-space for radio signals among any cell, and the radio free space can be switched instantaneously according to the demands of the mobile users or service providers.
{"title":"Theoretical Consideration On Nonlinear Distortion Suppression In Directly Optical FM Microwave over Fiber System","authors":"K. Tsukamoto, S. Fujii, Park Sanjo, S. Komaki","doi":"10.1109/MWP.1997.740274","DOIUrl":"https://doi.org/10.1109/MWP.1997.740274","url":null,"abstract":"and to use higher carrier frequencies and their wide frequency bandwidth under the trend of multimedia expansion of mobile radio, called mobile computing and mobile video services. These micro/pico cellular technologies will pose the following new problems: (1) many radio base stations for wide area service; (2) a long implementation time and a large investment for future new service; (3) excess base station equipment due to increasing traffic peak factor. To solve the above problems, radio highway network has been proposed [ 13. This network consists of Fiber and Radio Extension Link (FREx Link) [2] [3], so called microwave-over-fiber link and photonic switching routing nodes. (Fig. 1) In the network, radio signals transmitted by the radio terminals are encapsulated into optical signal and transferred to the appropriate remote radio control station via several optical routing nodes with their radio signal format kept. Consequently, the system can open the radio free-space for radio signals among any cell, and the radio free space can be switched instantaneously according to the demands of the mobile users or service providers.","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124968751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Noise Reduction In Passive Mode-locked Semiconductor Lasers By Subbarmoning Locking","authors":"F. Camacho, E. Avrutin, A. C. Bryce, J. Marsh","doi":"10.1109/MWP.1997.740226","DOIUrl":"https://doi.org/10.1109/MWP.1997.740226","url":null,"abstract":"","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130322278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High-speed Travelling-wave Photodetectors For Wireless Optical Millimeter Wave Transmission","authors":"M. Alles, U. Auer, F. Tegude, D. Jager","doi":"10.1109/MWP.1997.740237","DOIUrl":"https://doi.org/10.1109/MWP.1997.740237","url":null,"abstract":"","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133914781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optical Signal Processing Array Antenna Studies In ATR For Advanced Wireless Communication Systems","authors":"K. Inagaki, Y. Ji, O. Shibata, Y. Karasawa","doi":"10.1109/MWP.1997.740218","DOIUrl":"https://doi.org/10.1109/MWP.1997.740218","url":null,"abstract":"","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130666886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have estimated the phase-noise of a mode-locked fiber ring laser. The generated laser pulses have 270 fs duration with a repetition rate of 45.4 MHz, which is pumped by a laser diode. Afeedback loop is used to reduce the intensity fluctuation of the pump source and the laser cavity is clmely controlled for the air fluctuation in a sealed box. The phase-noise of the laser is measured in the frequency domain by using a radio-frequency spectrum analyzer. The timing jitter between pulse:-to-pulse was below 0.73 ps in an integrated frequency offset from 30 Hz to 3 kHz.
{"title":"Phase-noise Reduction In A Passively Mode-locked Fiber Ring Laser","authors":"M. Endo, G. Ghosh, Y. Tanaka","doi":"10.1109/MWP.1997.740250","DOIUrl":"https://doi.org/10.1109/MWP.1997.740250","url":null,"abstract":"We have estimated the phase-noise of a mode-locked fiber ring laser. The generated laser pulses have 270 fs duration with a repetition rate of 45.4 MHz, which is pumped by a laser diode. Afeedback loop is used to reduce the intensity fluctuation of the pump source and the laser cavity is clmely controlled for the air fluctuation in a sealed box. The phase-noise of the laser is measured in the frequency domain by using a radio-frequency spectrum analyzer. The timing jitter between pulse:-to-pulse was below 0.73 ps in an integrated frequency offset from 30 Hz to 3 kHz.","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121337851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tho merits of optical rf beamforming an roviowod, together with tho P s r f o n n ~ c ~ and limitations of cumat systoma. Exparimental rmults nre presented on one configusdon operated at 1.3 and 10 GHz in conjunction with lhw and confomd antenna array. Introdaction The inhbiem advantages of phowd May antonnaa over thoir muchanica~ly-mmnod counterparts havo long been rcscognistd [l], but h v o not tmen widely exploited to dato due to &e technological difneultios and co8t of thok implementation. Modem optical camponem and tuchniques appaar to o& sohdonr to many of tho Ceahnok~gicai problem [2-S] but until racently have remahad reln!ively oxpensive. Nwdelcss the “ea of optics in teleco”unidons, technologicrl bmakthroughs, and the pof the mdwtplacr, are &in& prices down, so that optically tontrolbd phaasd a m y antonma are IUreJy to bumno mlhbla and affordable ill the near ftlnIrc!. lhsy will be dopioyod in civil and military cammunications syaSms and radara, and in purely military rpplication~ such as BSM and ECM. Tbis paper begins by summarising the bS0efItt1 of phawrl m y M~BMIM, and the attractions of optid (photonic) techniques, especially in the contcrxt of this application, This is followed by a brief review of one particular twhniquu undw invosdgation in DERA which was Anrt described in MWP’% [6], togaha with mwnt modifications, and measurements in codunction with linear and conformal antenna m y a at 1,3 aad 10 OHz. The pepor concludea with the author’s apeculation on the, future of optid “forming. Pluued army antennas The principal attractions of phased array entonna tochniqueo art sumarisod below! Opthi (Photon&) Twhaiquw The principal aaraccions of optid te~~hniquea in the contact of if baanfarming am: The wmpactnw~s and lightweight of modem apticrl components, which o h derive firom the short wawtengtb (of o& ono micron). 0 The axtrane baudwidth capability, lowlow, and flexibility of optical fibre, which ~ f o spooially valuable for m o t e andlor deployable M-, ag conformal m y s on aim&, and apace-launched antenna 7 8 . Tho immunity of eignalrs in the optical domain to Eled~oMagnetic Interfmnw. Review of DERA optical rl beamfbrmer, 4 t h recent meaeuramentn. The principles of a rather simple and elegant optical rf beamformer were demribed at MWP’96 [6], together with preliminary measurements of radiation pattarns from a 9element 1,3 GHz linear nntennol m y . The buamfoming stru~arrr, used is reproduced in Figure 1, topther with details of the rust of the ante“ test facifity at DERA, Malvern. The most critical optical components of the beamformer are:(a) Two highiy-coherent 40mW didopumped YAG lasers h m Lighlwava Electronics, whose hqusncy separation can be varied from 0 to 100 GHz. By combining the outputs of these lesorsl a 1009’0 amplitudemodulamd sine wave envelop is incident on tho photodetectors, making optimum usa of both the available 1-r power and detector power=handllng capability, (b) A Meadowlark linear-nemadc liquidcrystal
本文分析了光学射频波束形成和光学波束形成的优点，以及光学波束形成和光学系统的局限性。给出了在1.3 GHz和10ghz工作的一种配置下，结合lhw和concomd天线阵列的实验结果。长期以来，人们一直认识到新型纳米技术相对于机械纳米技术的优势[1]，但由于技术上的困难和实施成本的原因，这种技术并没有得到广泛的利用。现代光学原理和技术似乎可以解决许多光学问题[2-S]，但直到最近还没有解决。普及oxpensive。现在，随着“电信中的光学时代”的到来，技术的突破和替代品的出现，价格都在下降，因此，在不久的将来，光学控制的相位传输将变得更加便宜，而且价格也能负担得起。lhsy将用于民用和军用通信系统和雷达，以及纯军事应用，如BSM和电子对抗。本文首先总结了phwrl m ~ m ~BMIM的bs0efit1，以及光学(光子)技术的吸引力，特别是在此应用的背景下，然后简要回顾了在DERA中进行的一项特定的双波导波导研究，该研究在MWP ' %[6]中有所描述，并进行了mwnt修改，以及在1,3和10 hz下使用线性和共形天线mya进行的测量。最后，作者对光学成形的未来进行了展望。下面总结了相控阵天线技术的主要优点!光学(光子)技术在农作接触中的主要作用是:现代微粒元件的轻量化和轻量化，这是由于其波长短(0 ~ 1微米)。光纤的超频宽能力、低带宽和灵活性，对高速发射天线、可部署天线、瞄准天线和快速发射天线具有特别的价值。光域信号对电磁干扰的抗扰性。DERA光束形成器的综述，4和最近的测量。在MWP ' 96[6]上描述了一个相当简单而优雅的光学射频波束形成器的原理，并对来自9元1.3 GHz线性互联网的辐射图进行了初步测量。图1再现了所使用的变形结构，以及马尔文DERA的ante”测试设施的锈蚀细节。波束形成器最关键的光学元件是:(a)两个高相干40mW双掺镱激光器，其频率间隔可在0 - 100ghz之间变化。(b)一个Meadowlark线性向列液晶Shapeshifbr相位SLM，在2SO-miomn间距上包含128个像素的线性排列，通过将这些传感器的输出与1009 ' 0振幅的正弦波包络相结合，使可用的1-r功率和探测器功率=处理能力得到最佳利用。该SLM的每个像素在600度的相位范围内都是电可控的，像素之间具有极高的可扩展性。图2中说明了这一点，顺便说一下，它比M光学相位测量更准确，因为它是在电域中进行的。这种纯相位SLh4有效地充当了频率无关的微波移相器。值得注意的是，该方案能够为阵列提供任意相位模式，而不局限于可验证的线性相位。类似地，可以通过第二个(振幅)SLM引入任意振幅图案，例如在第二个激光器的路径中。这提供了总天线
{"title":"coherrent Optical RF Beamforming","authors":"M. F. Lewis","doi":"10.1109/MWP.1997.740217","DOIUrl":"https://doi.org/10.1109/MWP.1997.740217","url":null,"abstract":"Tho merits of optical rf beamforming an roviowod, together with tho P s r f o n n ~ c ~ and limitations of cumat systoma. Exparimental rmults nre presented on one configusdon operated at 1.3 and 10 GHz in conjunction with lhw and confomd antenna array. Introdaction The inhbiem advantages of phowd May antonnaa over thoir muchanica~ly-mmnod counterparts havo long been rcscognistd [l], but h v o not tmen widely exploited to dato due to &e technological difneultios and co8t of thok implementation. Modem optical camponem and tuchniques appaar to o& sohdonr to many of tho Ceahnok~gicai problem [2-S] but until racently have remahad reln!ively oxpensive. Nwdelcss the “ea of optics in teleco”unidons, technologicrl bmakthroughs, and the pof the mdwtplacr, are &in& prices down, so that optically tontrolbd phaasd a m y antonma are IUreJy to bumno mlhbla and affordable ill the near ftlnIrc!. lhsy will be dopioyod in civil and military cammunications syaSms and radara, and in purely military rpplication~ such as BSM and ECM. Tbis paper begins by summarising the bS0efItt1 of phawrl m y M~BMIM, and the attractions of optid (photonic) techniques, especially in the contcrxt of this application, This is followed by a brief review of one particular twhniquu undw invosdgation in DERA which was Anrt described in MWP’% [6], togaha with mwnt modifications, and measurements in codunction with linear and conformal antenna m y a at 1,3 aad 10 OHz. The pepor concludea with the author’s apeculation on the, future of optid “forming. Pluued army antennas The principal attractions of phased array entonna tochniqueo art sumarisod below! Opthi (Photon&) Twhaiquw The principal aaraccions of optid te~~hniquea in the contact of if baanfarming am: The wmpactnw~s and lightweight of modem apticrl components, which o h derive firom the short wawtengtb (of o& ono micron). 0 The axtrane baudwidth capability, lowlow, and flexibility of optical fibre, which ~ f o spooially valuable for m o t e andlor deployable M-, ag conformal m y s on aim&, and apace-launched antenna 7 8 . Tho immunity of eignalrs in the optical domain to Eled~oMagnetic Interfmnw. Review of DERA optical rl beamfbrmer, 4 t h recent meaeuramentn. The principles of a rather simple and elegant optical rf beamformer were demribed at MWP’96 [6], together with preliminary measurements of radiation pattarns from a 9element 1,3 GHz linear nntennol m y . The buamfoming stru~arrr, used is reproduced in Figure 1, topther with details of the rust of the ante“ test facifity at DERA, Malvern. The most critical optical components of the beamformer are:(a) Two highiy-coherent 40mW didopumped YAG lasers h m Lighlwava Electronics, whose hqusncy separation can be varied from 0 to 100 GHz. By combining the outputs of these lesorsl a 1009’0 amplitudemodulamd sine wave envelop is incident on tho photodetectors, making optimum usa of both the available 1-r power and detector power=handllng capability, (b) A Meadowlark linear-nemadc liquidcrystal","PeriodicalId":280865,"journal":{"name":"International Topical Meeting on Microwave Photonics (MWP1997)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129009386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Pfitzenmaier, E. H. Bottcher, E. Droge, D. Bimberg
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