JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO.7, APRIL 1, 2010 1071 Coherence-Controlled mm-Wave Generation Using a Frequency-Shifting Recirculating Delay Line Cibby Pulikkaseril, Student Member, IEEE, Stephen M. Hanham, Student Member, IEEE, Robert Shaw, Robert A. Minasian, Fellow, IEEE, Fellow, OSA, and Trevor S. Bird, Fellow, IEEE Abstract—A photonic technique based on optical heterodyning for the generation of microwave and millimeter-wave signals is presented in this paper. Coherence control of a comb of time-delayed and frequency-shifted optical signals is used to selectively beat multiple optical signals together to produce a stable, spectrally pure microwave, or millimeter-wave signal. This approach is demonstrated by generating signals at 11.25 and 30 GHz. The linewidth of the generated signal is independent of the linewidth of the optical source employed, and is shown to be less than 100 Hz with sideband suppression 30 dB. Index Terms—Microwave photonics, optical millimeter-wave (mm-wave) generation. I. INTRODUCTION HE generation of millimeter wave (mm-wave) and terahertz (THz) signals is of significance for a diverse range of applications, including communications, spectroscopy, and radio astronomy. Frequency stable, narrow-linewidth signals are of particular interest for use as local oscillators and sources for high-resolution THz spectroscopy, as well as radio-over-fiber (ROF) applications. Photonic techniques offer an attractive method for generating stable, narrow-linewidth mm-wave, and THz signals, and they have the advantage of allowing ease of distribution over optical fiber prior to conversion into the electrical domain. A large range of techniques have been described in the literature for generating the suitable optical signals for heterodyning to produce a, mm-wave beat signal. Phase or injection locking of one or more lasers [1]–[3] can produce very narrow-linewidth signals with good suppression of unwanted tones. The disadvantage of these schemes is their complexity and cost. An alternate approach is the use of multimode or multiwavelength, DFB [4], [5], and fiber lasers [6], [7]. T There also exists a range of photonic techniques that use external amplitude [8], [9] or phase modulation [10], [11] of a single laser source. These techniques have the advantage of low complexity and cost, and are capable of producing a narrowlinewidth signal. A limitation can be the maximum frequency multiplication factor of the electronic source that is realizable. Kawanishi et al. overcame this problem by including a modulator inside a fiber cavity, and used recirculation to enhance the sideband generation and increase the number of multiplications possible [8]. The interested reader can find a review of these generation techniques in [12] and [13]. The objective of this paper is to present a new photonic technique for generating narrow-linewidth microwave and mm-wave signals, which has the advantage that the frequency of the generated signal can be readily reconfigured. It is based on the use of the concept of mutual coherence to control the beating of lines produced from a broadband optical source fed into an unbalanced Mach–Zehnder interferometer (MZI), followed by a frequency-shifting recirculating delay line (FS-RDL) to produce a single narrow-linewidth mm-wave signal. In addition to offering a simple method for changing the frequency of the generated signal, this approach also enables the use of an inexpensive, broad-linewidth optical source. Results are presented that demonstrate the generation of stable microwave and mm-wave signals with a high sideband suppression ratio (SSR) and a narrow linewidth. This paper is organized as follows. The principle of operation and structure of the coherence-controlled signal generation technique is described in Section II. Section III presents a theoretical analysis of the predicted spectrum. Section IV presents the simulation results, and Section V describes the experimental results. Finally, the results are discussed in Section VI. II. COHERENCE-CONTROLLED MM-WAVE GENERATION The new structure for generating narrow-linewidth mm-wave signals, based on the concept of mutual coherence, is shown in Fig. 1. Light from a broadband optical source is passed into an unbalanced MZI, and is then fed into an FS-RDL. The output light is detected by a photodetector, which produces a beat signal at its output. The structure is similar to previously proposed structures used for coherence multiplexing [14]–[16], where multiple signals are differentiated using relative coherence and a frequency shifter is used to demultiplex them into frequency-separated signals. However, in this paper, we modify this to obtain a new concept for generating a single tone at a desired frequency. The unbalanced MZI formed by connecting two optical couplers with coupling coefficients of and has a path delay difference of between its two arms. This is followed by the Manuscript received August 04, 2009; revised November 04, 2009. First published December 22, 2009; current version published March 05, 2010. This work was supported in part by the Australian Research Council and the Commonwealth Scientific and Industrial Research Organisation. C. Pulikkaseril and R. A. Minasian are with the School of Electrical and Information Engineering, University of Sydney, Sydney, N.S.W. 2006, Australia (e-mail:
[email protected]). S. M. Hanham is with the School of Electrical and Information Engineering, University of Sydney, Sydney, N.S.W. 2006, Australia, and also with the Commonwealth Scientific and Industrial Research Organisation Information and Communication Technology Centre, Sydney, N.S.W. 1710, Australia. T. S. Bird and R. Shaw are with the Commonwealth Scientific and Industrial Research Organisation Information and Communication Technology Centre, Sydney, N.S.W. 1710, Australia. Digital Object Identifier 10.1109/JLT.2009.2038725 0733-8724/$26.00 © 2010 IEEE General schematic of the device (PD = photodetector. In this paper.1072 JOURNAL OF LIGHTWAVE TECHNOLOGY. 28. FS = frequency shifter. VOL. as well as the signal-spontaneous beat noise and the spontaneous-spontaneous beat noise. 1. and OA = optical ampli. the phase-induced intensity noise of the FS-RDL has been analyzed. 7. The first case results in an output electric field incident on the photodetector of Fig. APRIL 1. NO. which has used the FS-RDL to realize a high-resolution microwave photonic bandpass filter. 2010 results discussed in [18]. Mutual coherence only occurs in case 1) and only when . Under the condition that . the delays. which is the loop losses subtracted from the amplifier gain. . for each recirculation. used to compensate for the losses in the loop. Additionally. of the FS-RDL loop delay time. where we assume that the only random process is the time-varying optical phase. producing a delta function spectrum. quency shift in the loop. and recirculates times in the FS-RDL. is the time-varying random phase is given by of the optical source. The autocorrelation for case 1) is given by (4) . . they will beat coherently [17]. if they do not arrive at exactly the same time. to be an exact integer multiple. and (2) with and is the net gain of the FS-RDL. i. which can be assumed to be a Wiener–Levy process [17]. i. thus providing an overall loop gain . . The second case produces the same spectrum as the FS-RDL phase-induced intensity noise spectrum (PIIN) with a broad-linewidth source. . The photodetector responds to the output optical intensity of the device. the two beating signals are incoherent. when . This is realized by designing the unbalanced MZI delay time. which is given by where (3) and is the intensity of the optical source. In practice. but has recirculated times in the FS-RDL. These will beat coherently at the photodetector to produce a single tone with frequency at the photodetector output. The principle of operation is based on designing multiple light paths in the structure. To derive an expression for the power spectral density of this current. is the angular where is the angular freoptical frequency of the input. Case 2): Light from the same arm of the MZI recirculates and times in the FS-RDL and beats together at the photodetector. similar to the (1) is the input electric field amplitude. III.e. producing a narrow tone at . Moreover. Case 1): Light from the short arm of the MZI recirculates times in the FS-RDL and beats with light that was delayed by in the long arm of the MZI. The FS-RDL produces a time for each recirculation and also a fixed optical fredelay of . and . POWER SPECTRAL DENSITY ANALYSIS The spectrum analyzer displays the spectral density of the output current from the photodetector. we study the autocorrelation of the output optical intensity. so that only selected light paths with a determined frequency offset beat coherently at the photodetector while all other light paths beat incoherently. light that has passed through the delayed branch in the MZI and has recirculated times will arrive at the photodetector at exactly the same time as light passing through the short arm of the loop.. comprising a loop formed by using an optical couand having an optical frepler with a coupling coefficient of quency shifter inside the loop. FS-RDL. as long as the signals arrive within the coherence time of the optical source..er). are selected for both be much longer than the coherence time of the optical source. producing a noise spectrum at a level below the coherent beat tone. An optical amplifier is quency shift. the condition guarantees that all other combinations of light paths beat incoherently.e. . We can predict the spectral characteristics of this photocurrent by considering the following two cases. which occurs when pairs of signals that have traveled through different MZI paths beat at the photodetector. the resulting power spectrum collapses from a laser phase spectrum of arbitrary coherence to a delta function spectrum. the PIIN spectrum is considered to dominate over both signal-spontaneous and spontaneous-spontaneous beat noise spectra [20]. except that the index “a” is replaced by “b. lines with a different frequency offset beat incoherently. IV. the power spectral density of case 1). as has also been done previously [16]. and MHz. The noise power spectral density of this case is identical to (10). it should be noted that this analysis neglects the contribution of amplified spontaneous emission (ASE) noise from the FS-RDL optical amplifier. thus producing Lorentzian spectra. Fig. 40. given a source linewidth of MHz. The reason is that since the structure produces incoherent beat noise at all frequencies. [19]. can be expressed as Fig. they have traveled the same distance. 39. the term and 41. lations in the FS-RDL is the total number of recircu- (5) with (6) (7) (8) The total power spectral density of the device is given by the sum of the power spectral densities of the two cases 1) and 2) as follows: (9) The Wiener–Khinchine theorem is used to obtain the power spectral density from the autocorrelation function. is plotted for Using (11). we design the MZI length difference to be 40 times the FS-RDL loop length. Term F (!) plotted for M = 38. 3 shows the resulting power spectrum output. a sharp delta signal is produced at 30 GHz.: COHERENCE-CONTROLLED MM-WAVE GENERATION USING A FREQUENCY-SHIFTING RECIRCULATING DELAY LINE 1073 where denotes convolution. The delta function spectrum is produced at 30 GHz from the beating of lines that are 40 recirculations apart. A narrowlinewidth signal centered at 30 GHz is generated. However. and 41.PULIKKASERIL et al. 2. m.e. 2 shows that . Case 2) occurs when pairs of signals that have traveled through the same arm of the MZI beat at the photodetector and produces the PIIN spectrum of an FS-RDL operating in the incoherent regime. and for m. we consider the generation of a 30 GHz tone. Conversely.. the RF signal driving the frequency shifter is multiplied to a higher frequency signal. i. Since the generated signal is formed by the beating of optical signals that are ideally coherent. It for is required to align the genshould be noted that precision in erated tone with one of the resonant peaks of the FS-RDL to ensure that the signal power improves relative to the other peaks. SIMULATION RESULTS Using the expressions that were derived in the previous section. . Using a frequency shift of 750 MHz inside the loop. As an example. Fig. Fig.” and is given by (13) where and . with a noise (10) where (12) and . Applying this theorem. 2 depicts the phenomenon of mutual coherence. simulations were carried out to predict the power spectral density of the coherence-controlled mm-wave signal generator. The result is that a broad-linewidth optical source can be used to produce a narrow-linewidth signal and a relatively low-frequency shift can produce a high-frequency tone. In effect. of an inaccuracy in the matching of L to L . 4. a perfect length match results in the highest SSR. The SSR. however. APRIL 1. Effect on the SSR. and this is a design choice to increase the signal power by matching the signal frequency to a resonant peak of the loop. and recirculations. 5 shows the effect of the loop gain on the SSR for various optical source linewidths. A consequence of this effect is that the experimental realization of this device needs to include a tunable optical delay line to accurately adjust the length of the loop. the greater the penalty in the SSR reduction due to a given fiber length mismatch. 4 shows the effect on the SSR of inaccuracy in the to for various optical source linewidths. The SSR continues to increase as the optical source linewidth increases. = 40 Fig. to 30 GHz by changing V. 7. = 40 Fig. Fig. 5. and 1 GHz. 2010 Fig. matching of As expected. EXPERIMENTAL RESULTS In order to verify the coherence-controlled mm-wave generation concept. experiments were set up using the configuration . This changes .25 from 15 to 40 .1074 JOURNAL OF LIGHTWAVE TECHNOLOGY. It can be seen that the broader the optical source linewidth is. 28. for optical source linewidths of 100 and 250 MHz. VOL. Sideband suppression ratio versus overall loop gain G for optical source linewidths of 100 and 250 MHz. Tuning the generated signal frequency by adjusting the MZI length. Fig. L . which controls the number of frequency-shifted recirculations. 6. requirements between Fig. The results indicate that a broad will produce linewidth coupled with high loop gain the optimum SSR. This analysis assumes that the desired tone is aligned with a resonant peak of the recirculating loop. separating signals that beat coherently at the photodetector. 6 shows that the generated signal frequency is tuned from 11. the linewidth should not be too broad because a broad-linewidth source has a smaller coherence length. and 1 GHz. which is defined as the ratio of the power of the desired signal compared to the highest adjacent sideband power. 3. It can be noted that though the source can have a broad linewidth. increasingly larger linewidths are required to make incremental improvements in the SSR. = 40 floor arising from the PIIN of the FS-RDL. limit the linewidth that can be used. NO. Predicted spectrum for a generated 30 GHz signal corresponding to recirculations. for practical considerations. and recirculations. and practical considerations. is maximized when the desired signal is aligned with one of the resonant peaks of the recirculating loop. Fig. An important advantage of the coherence-controlled signal generation source is that the generated signal frequency can be tuned to another multiple of the frequency shifter by simply changing the length of an arm of the MZI. such as the finite gain bandwidth of the optical amplifier and increased sensitivity to fiber perturbations. The 30 GHz signal is aligned with a resonant peak of the recirculating loop. which imposes more stringent length matching and . To prevent out-of-band ASE noise from recirculating in the loop. 8. and m. the phase noise exhibits a degradation because fluctuations are increased by a factor and a similar effect has been demonstrated for photonically generated oscillators [8]. This is due to the presence of the frequency shifter in the loop.5 dB can be seen. It should be pointed out that the RF signal driver to the frequency shifter should have high spectral purity. whose linewidth was broadened by using the instrument’s inbuilt coherence control function. m. in prac- . Fig. and the power spectrum was displayed on an electrical spectrum analyzer. m. which enabled the generation of a broad-linewidth optical source. The initial configuration was designed to produce a coherence-controlled signal after 15 recirculations.25 GHz. Thus. and in addition also had its output phase modulated with a 500 MHz pseudorandom bit sequence (PRBS). an Agilent E8257D source set to 750 MHz followed by a power amplifier was used to drive the AOFS. thus preventing self-oscillation. as described in [21]. and for this purpose. The principle of the instrument’s inbuilt coherence control was based on modulating the laser cavity length to make its spectrum linewidth wider. and PD = photodetector). 7. In order to broaden the linewidth further to beyond several hundred megahertzs. which was readily achieved with the tun- Fig. 9. [22]. Experimental setup (PM = phase modulator. 8 also shows the predicted spectrum using parameters of MHz. The precision in the loop length is a result i.. The output was detected by an amplified photodetector with a 12 GHz bandwidth. at 11. A high measured SSR of 35.25 GHz signal using a low phase noise frequency shifter driver. which was 8 dBm lower than the drive power required by the AOFS. but. the output was phase modulated by the 500 MHz PRBS sequence. especially if a large number of recirculations are used. where the linewidth was also tunable by changing the PRBS modulation.25 GHz.e. The output of the power amplifier was 22 dBm. The measured spectrum is shown in Fig. this was compensated by using a high-gain erbium-doped fiber amplifier (EDFA) in the loop.25 GHz signal. however..5 nm. having an output power of 10 dBm at 1559. Fig. The peak in the plot at around 20 kHz is an artifact caused by the source laser instrument’s inbuilt coherence control function. The broadband optical source was implemented using a tunable laser (Santec TSL-210). i. which was verified by its disappearance when this function was disabled. 7.PULIKKASERIL et al. This caused an increase in the insertion loss of the AOFS. of the precise alignment required to match the desired signal to a resonant peak. A tunable optical delay line was included in the loop to allow the loop length to be adjusted to ensure that the generated signal aligned with a resonant peak of the recirculating delay line. m. In the case of an electronic oscillator whose frequency is multiplied by n. Fig. it is important to use an RF signal driver with low phase noise. Good agreement can be seen between measurement and prediction. = shown in Fig.: COHERENCE-CONTROLLED MM-WAVE GENERATION USING A FREQUENCY-SHIFTING RECIRCULATING DELAY LINE 1075 Fig. Measured single sideband phase noise for the generated 11. the The length of the loop was set to be required unbalanced delay in the MZI was 15 times this value. which causes each recirculation to be frequency shifted. We have not observed oscillations in the FS-RDL when it has been used for generating mm-wave signals. The frequency shift was implemented using a 750 MHz acousto-optic frequency shifter (AOFS) (Brimrose). The coherence control function was nevertheless necessary to achieve sufficient linewidth broadening of the optical source. MHz. It can be noted that the FS-RDL is highly resistant to lasing or self-oscillation and quite stable.e. Generated 11. PC polarization controller. 8 taken with a resolution bandwidth of 10 kHz. an optical filter was also placed after the AOFS. 9 shows the measured phase noise. hence. able optical delay line. A tone is produced at 11. Comparison of experimental results with theory for the generated 30 GHz signal. 7. in combination with a high-frequency photodetector or photomixer and a gain medium in the loop with sufficient bandwidth to support such a comb. whether the requirement on the light arriving by different paths within the coherence time to beat coherently. Entire spectrum for the generated 30 GHz signal. DISCUSSION The experimental results shown in Section V demonstrate the validity of using coherence control to generate narrow-linewidth high-frequency mm-wave or microwave signals.5 dB compares favorably with other published results [2]. Fig. [10]. APRIL 1. VOL. by using an optical source with a broader linewidth. 12. We have investigated. VI. 2010 Fig. [7]. (a) Predicted and (b) measured results. A reduction of the PIIN noise. It can be seen that a very pure tone at 30 GHz has been produced. Comparison of experimental results with theory for the generated 30 GHz signal. Fig. The optical power incident on the photodetector was 5. using the model. and the former can be made to be very stable. i. Figs. [24]. it could be dispensed with by replacing the laser with a broadband optical source. This was done by simply increasing the became 40 times ratio between the MZI and loop lengths. 10. tice. [9]. Another driver for the AOFS was used in this experiment. For the experimental parameters Fig. the frequency of the generated signal was changed to 30 GHz. This is because the frequency stability of the device depends on the RF source driving the frequency shifter. 10 shows the measured spectrum. 11.25 and 30 GHz.. not the optical signal.1076 JOURNAL OF LIGHTWAVE TECHNOLOGY. with the unbalanced length of the MZI set to 30 times the length of the FS-RDL. thereby enabling the generation of terahertz signals if a sufficiently wide comb of frequencies can be produced. an unamplified phoPhotonics) was used todetector with a 50 GHz bandwidth ( to measure the signal. which causes perturbations in the light paths. could further improve this value. [3]. NO. the generated signal did not exhibit any frequency jitter or drift over an observation period of 8 h. The measured SRR of 35. This could be achieved by using optical frequency shifters with a larger frequency shift. For instance. This is believed to be caused by mechanical vibrations or thermal fluctuations of the optical fibers. The measured is below linewidth of the generated signal was less than 100 Hz. or whether the requirement on the loop length being in precise alignment to align the generated signal with a resonant peak of the recirculating delay line. For this 30 GHz signal generation case. for example. our theoretical model indicates that the approach will scale to higher frequencies. 11 and 12 show a closer view of the generated tone. Although this technique was demonstrated for 11. The phase noise of the system at small offset frequencies of around 300–400 Hz is higher than that reported for phase and injection locking schemes [2]. The frequency of the generated signal was observed to be quite stable. Finally. [3]. dBc/Hz at 3 kHz from the carrier and The phase noise is dBc/Hz at 1 MHz from the carrier. 28. such as electrooptic frequency shifters that have shown 25 GHz frequency shift [23]. is more critical and sensitive to perturbations. with virtually no spurious signals. which corresponds to 40 recirculations of the 750 MHz frequency shift. so . a 300 GHz signal could be generated by using a 10 GHz electrooptic frequency shifter. .0 dBm.e. A good agreement between measurements and predictions can be seen. optically injection locked lasers. 17. Australia. X. Seeds. K. [15] D. 14. to be published.. Lima.Eng. vol. Sep. and T. and B. ACKNOWLEDGMENT The authors would like to acknowledge B. Oct. no. Shimizu. vol. He is currently working toward the Ph. Sep. LT-4. pp. 2009. no. and A. 1289–1297. Lightw. 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Australia. photonic signal processing. From 1976 to 1978. and B. He was the recipient of the 2000 IEEE Third Millennium Medal for outstanding contributions to the IEEE New South Wales Section.A. He was a Distinguished Lecturer for the IEEE Antennas and Propagation Society from 1997 to 1999. he was awarded a Centenary Medal for service to Australian Society in telecommunications. Antennas and Propagation 2000. Minasian (S’78–M’80–SM’00–F’03) received the B.. where he held several positions with CSIRO. He is an Associate Editor of the Optical Fiber Technology.. Melbourne. Sydney. His research interests include terahertz technology. He was the recipient of the CSIRO Medal Award in 1990 for the development of an Optus-B satellite spot beam antenna. from the University of Melbourne. degrees from the University of Sydney. Since February 1996. He was an Associate Editor of the IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION from 2001 to 2004.App. London. Currently. University of Sydney. in 1971.. During 1982 and 1983. N. . He is currently working toward the Ph. degrees from the University of Western Australia. a member of the Administrative Committee of the IEEE Antennas and Propagation Society from 2003 to 2005. 1992. and Ph.W. and was also named Professional Engineer of the Year by the Sydney Division of Engineers Australia. In December 1983. Australia. and in 2001. and the B.Sc. microwave photonics.. He has published widely in the areas of antennas.1078 JOURNAL OF LIGHTWAVE TECHNOLOGY. he was with OTC. degree from the University of Melbourne. and microwave photonics. he has been with the Commonwealth Scientific and Industrial Research Organization Information and Communications Technology Centre. where he is currently an RF Engineer. James Cook University of North Queensland. and the Communications Research Laboratory. awarded by the Australian Telecommunications and Electronics Research Board. for the best paper published annually in the Journal of Electrical and Electronic Engineering.. Robert Shaw received the B. He was a Lecturer in the Department of Electrical Engineering. Australia. From 1985 to 1992. 7. Australia. and was the Head of the School of Electrical and Information Engineering. he was a Postdoctoral Research Fellow at Queen Mary College. Vic.. and the Ph. 28.W. where he is also the Director of the Fibre-Optics and Photonics Laboratory.S. University of Sydney. degree from Moore Theological College. 2010 Stephen M. He also holds various patents and has done consulting work with industry. wireless. the M. in conjunction with the Commonwealth Scientific and Industrial Research Organization Information and Communications Technology Centre.D. 1995. and again in 1998 for the multibeam antenna feed system for the Parkes radio telescope. Minasian is a Fellow of the Optical Society of America. Australia. U.W. He has been the Editor-in-Chief of the IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION since 2004. broadband optical communications.. electromagnetics. 1973. the Asia-Pacific Microwave Photonics Conference (APMP2006APMP2009). degree in the School of Electrical and Information Engineering. he was the corecipient of the H. respectively. he was with Alcatel-TCC. U.S. he joined the Commonwealth Scientific and Industrial Research Organization (CSIRO). he received the John Madsen Medal of the Institution of Engineers. M. NO. the Chairman of the 2000 Asia Pacific Microwave Conference. He has served on the Australian Research Council as a member of the College of Experts. Australia. and satellite communication antennas. His research interests include optical signal processing and telecommunications. Millimeter and Terahertz Waves. N. and the IEEE Laser and Electro-Optics Society Annual Meeting (LEOS2005). Melbourne. the Asia Pacific Microwave Conference. respectively. Robert A. In 1988. Engineering projects that he played a major role in were given awards by the Society of Satellite Professionals International (New York) in 2004. U.W. Dr. He is a member of the Technical Committee on Microwave Photonics of the IEEE Microwave Theory and Techniques Society (IEEE MTT-S). Sydney. and optical phased arrays. the IEEE International Microwave Symposium (IMS2006). Wheeler Applications Prize Paper Award from the IEEE Antennas and Propagation Society.Sc. A.Sc. he is member of the Editorial Boards of the IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES and the Journal of Infrared. In 2003. and 1977. degrees from the University of Melbourne.S. and is a CSIRO Fellow. in 2000. He holds 12 patents. antennas. Perth. Australia. Australia.Th. Australia. W. Sydney.Sc. Sydney. and is currently the Chief Scientist in the CSIRO Information and Communications Technology Centre. VOL. His biography is listed in Who’s Who in Australia.App. and was the Vice Chair and Chair of the Section in 1999–2000 and 2001–2002. and has served and is on the program committees for several international conferences including the IEEE International Meeting on Microwave Photonics (MWP2003–MWP2009). the Conformity Assessment Program.K. he was a Consultant at Plessey Radar. Australia. Japan.S. Sydney. N. Trevor S. He has been a member of the technical committee of numerous conferences including the Joint Institute for Nuclear Astrophysics. University of London. and B. and a member of the College of Experts of the Australian Research Council from 2006–2007. Australia. Prof. waveguides. the Institution of Electrical Technology. He has contributed 238 technical publications in these areas. He is also a Fellow of the Institute of Engineers.K. Australia.. He is currently a Chair Professor in the School of Electrical and Information Engineering. degree from the University College.K..D.. University of London. Bird is a Fellow of the Australian Academy of Technological and Engineering Sciences.E. Hanham (S’03) received the B. Sydney. the Engineers Australia in 2001. London. and the URSI Electromagnetic Theory Symposium. a Member of the New South Wales Section Committee from 1995–2005. Bird (S’71–M’76–SM’85–F’97) received the B. He was the recipient of the ATERB Medal for Outstanding Investigator in Telecommunications.. the Chair of the New South Wales Joint AP/MTT Chapter from 1995 to 1998. for five years. N.K. Infrared and Millimeter Waves/THz. Vic.E. He is also an Adjunct Professor at Macquarie University.E. APRIL 1. Sydney.D. and again in 2003. U. and an Honorary Fellow of the Institution of Engineers.Sc. Sydney.