wdm optical interfaces for future fiber radio systems phần 5 pot

3.19: Optical spectra of the proposed WDM optical interface while modelled by VPI simulator using three WI-DWDM channels: a: the input signal at port IN, b: the downlink signal at port

signal at DL Drop port and the uplink signal at ADD port, generated by reusing the recovered optical carrier, were also quantified, which are shown in Fig 3.20 The error-free (at a BER of 10-9) data recovery and the recovered optical spectra verified

-50

Wavelength relative to 1552.22 (nm)

-30 -10

Wavelength relative to 1552.22 (nm)

-30 -20

Fig 3.19: Optical spectra of the proposed WDM optical interface while modelled by VPI

simulator using three WI-DWDM channels: (a): the input signal at port IN, (b): the downlink signal at port DL Drop, (c): the recovered optical carrier at λ-Re-Use port, and (d): the uplink

optical mm-wave signal to be added to the interface, generated by reusing the recovered optical

carrier

the functionality of the proposed interface, which was later demonstrated in experiment, as described in Section 3.5.3

-5

-5 -3

-11 -9

Received Optical Power (dBm)

Uplink at ADD Port

Received Optical Power (dBm)

Downlink at DL Drop Port

-5

-5 -3

-11 -9

Received Optical Power (dBm)

Uplink at ADD Port

-5

-5 -3

-11 -9

Received Optical Power (dBm)

Uplink at ADD Port

Received Optical Power (dBm)

Downlink at DL Drop Port

Received Optical Power (dBm)

Downlink at DL Drop Port

Fig 3.20: Simulation BER curves that quantify the degradation of the signals due to traversing the

proposed interface: (a): the recovered downlink signal at DL Drop port, and (b): the uplink signal,

generated by reusing the recovered optical carrier, at ADD port

3.7 Effects of the Performance of O/E Devices

The overall receiver sensitivity of the experimentally demonstrated system incorporating the proposed interface, irrespective of direction of communication, is less than or equal to -7.7 dBm at a BER of 10-9,which is very poor and needs to be improved through further investigation The performance of the optoelectronic and electrooptic devices such as DE-MZMs and the PD play a very important role in limiting the overall performance of the link The DE-MZMs used in the experiment exhibit a CSR from 22 to 28 dB Also, the PD used in the experiment had a responsitivity of less than 0.4 If the performance of O/E devices can be improved either by replacing it with better performing devices or by applying some external

performance enhancing techniques (such as CSR reduction by external means), the sensitivity limitation can be resolved quite easily

Fig 3.21 shows a simulation model developed by using VPI platform, which quantifies the performance enhancement of the system at different values of CSR at the output of the DE-MZMs and the responsitivity of the PD To make the results comparable, the properties of the modules in the model follow the experimental parameters very closely To enable variable CSRs in the generated WI-DWDM

signals, the sidebands of the OSSB+C signal are separated from the optical carriers using a Fabry Perot filter in conjunction with a 3 port optical circulator, where the intensities of the sidebands were varied by another EDFA (keeping the noise figure unchanged) before combining them back with the separated optical carriers Fig 3.22(a) shows the sensitivity at BER = 10-9 vs reduction in CSR curve obtained from simulation model, which clearly indicates that, the sensitivity of the system increases almost linearly with reduction in CSR

WDM Optical Interface 7

1

Uplink OSSB+C2

WDM Optical Interface 7

1

Uplink OSSB+C2

Fig 3.21: Simulation model that quantifies the performance enhancement of the system at

different values of the CSR of the DE-MZMs as well as the responsitivity of the photodetector

To verify the impact of the PD on the overall system performance, the responsitivity of the PD module in the simulation model were increased gradually from 20% up to 100% and plotted against the sensitivity of the system at BER = 10-9, which is shown in Fig 3.22(b) This curve also confirms that the sensitivity of the system increases almost linearly with responsitivity of the PD and saturates when the responsitivity > 0.9 A/W Therefore, both curves (Fig 3.22a- 3.22b) demonstrate that with proper selection of the O/E devices, the overall performance of the link can be enhanced significantly

-14 -12 -10 -8 -6 -4

-14 -12 -10 -8 -6 -4

-14 -12 -10 -8 -6 -4

S C

Fig 3.22: Simulation graphs that quantify the performance enhancement of the system at different

values of the CSR of the DE-MZMs as well as the responsitivity of the photodetector: (a): sensitivity vs reduction in CSR, and (b): sensitivity vs PD responsitivity

3.8 Carrier Reuse over Independent Uplink Light Source

As described in the previous sections, the proposed interface enables a carrier extraction technique that provides optical carrier to modulate the uplink mm-wave signals The downlink optical carrier traverses a series of optical devices, in addition

to propagating through a span of optical fibre before being recovered at the interface This transportation of the optical carrier to the interface may potentially cause broadening of the linewidth of the carrier-pulse due to the Group-Velocity Dispersion (GVD), which can be expressed mathematically [81] as follows:

2 2

2

ωβωω

βω

υω

L d

d d

dT

T

g

where,

υ g, is the group velocity,

β, is the propagation constant

L, is the length of SMF,

∆T, is the amount of pulse broadening,

∆ω, spectral width of the carrier pulse, and

= is the GVD parameter that determines the amount of broadening

In terms of range of wavelengths ∆λ, rather than frequency spread ∆ω, the extent

of pulse broadening ∆T can be expressed as:

( )

2 221

,

2

βλ

πυ

λ

λλ

υλ

ωω

d d

dT

T

g

g

β2, is the dispersion parameter expressed in unit of ps/(km-nm)

The above two expressions of pulse broadening demonstrates that there is a definite broadening of downlink carriers before being recovered in the proposed interface to be reused for uplink communication This dispersion induced pulse broadening contaminates the receiver performance by introducing Intersymbol Interference (ISI) and by reducing the SNR at the decision circuit

To quantify the effects of pulse broadening in a system incorporating the proposed interface, a simulation was carried out using VPITransmissionMaker5.5 The simulation model was very similar to the experiment, where uplink optical mm-wave signal was generated in two different ways: (i) by reusing the recovered downlink carrier, and (ii) by using an independent optical source In both cases, the BER curves were measured in the CO The simulation BER curves are presented in Fig 3.23 It shows that due to pulse broadening, the uplink signal experiences a 0.1 dB

-3

-5

-7 -9 -11

carrier reuse independent light-source

-3

-5

-7 -9 -11

carrier reuse independent light-source

Received Optical Power (dBm)

Fig 3.23: Simulated BER curves as a function of received optical power for uplink transmission

while: (i): reused the optical carrier recovered by the proposed interface, and (ii): used an

independent optical source as the uplink optical carrier.

additional penalty, which is very negligible, and can be ignored Therefore, the effect

of recovered carrier pulse broadening on the overall uplink performance is minimal and hence can be neglected while designing the mm-wave fibre-radio systems incorporating the proposed WDM optical interfaces

3.9 Conclusion

This chapter presented a multifunctional WDM optical interface for future DWDM fibre-radio system that enables dispersion tolerant OSSB+C modulation based wavelength-interleaved networks and capable of providing the optical carrier for the uplink transmission by exploiting a wavelength reuse technique The functionality of the proposed interface was verified experimentally as well as via simulation for three wavelength-interleaved DWDM channels with a channel spacing

of 25 GHz, each carrying 37.5 GHz RF signal with 155 Mb/s BPSK data transported over 10 km of fibre link The use of the demonstrated interface in the future DWDM fibre-radio networks can improve spectral efficiency and ensure efficient wavelength utilisation, while offers a simplified and consolidated BS architecture by eliminating the need for separate optical source for uplink In the design process we have taken the benefits of matured and standard component technologies that enhance the possibility of merging the mm-wave fibre-radio based BWA systems with existing optical network infrastructure in the access and metro domains

The effects of the performance of optoelectronic devices (DE-MZM and PD) in the overall performance of the link incorporating the proposed interface were investigated A simulation model was developed to investigate the impairments contributed by imperfect optical devices such as the DE-MZM and PD The CSR of the DE-MZM and the responsitivity of the PD were varied and the respective sensitivities were measured The results indicated that the performance of the links incorporating the proposed interface were largely dependent on the performance of the optoelectronic devices, and by proper selection of these devices, the performance

of the link can be significantly enhanced

A comparison was carried out to investigate the effects of pulse-broadening due to dispersion on the optical carriers recovered using wavelength reuse scheme and independent light-sources in the uplink path The mathematical expressions showed that there was a definite broadening of the optical carrier recovered by the proposed interface to be reused in the uplink path However, the simulation results demonstrated that the effects have minimal impact on the overall system performance and can be ignored while designing the mm-wave fibre radio systems incorporating the proposed WDM optical interface

3.10 References

[1] A J Cooper, “Fiber/radio for the provision of cordless/mobile telephony services in the

access network,” Electron Lett., vol 26, pp 2054-2056, 1990

[2] H Ogawa, D Polifko, and S Banba, “Millimeter wave fiber optics systems for personal

radio communication,” IEEE Trans Microwave Theory Tech., vol 40, pp 2285-2293, 1992 [3] J O’Reilly and P Lane, “Remote delivery of video services using mm-waves and optics,” J Lightwave Technol., vol 12, no 2, pp 369-375, 1994

[4] M Shibutani, T Kanai, W Domom, W Emura, and J Namiki, “Optical fiber feeder for

microcellular mobile communication system (H-O15),” IEEE Journal on Selected Areas in Communications, vol 11, pp 1118-1126, 1993

[5] W I Way, “Optical fibre-based microcellular systems: an overview,” IEICE Trans Commun., vol E 76-B, no 9, pp 1078-1090, 1993

[6] O K Tonguz and J Hanwook, “Personal communications access networks using subcarrier

multiplxed optical links,” J Lightwave Technol., vol 14, pp 1400-1409, 1996

[7] P Mahonen, T Saarinen, Z Shelby, and L Munoz, “Wireless Internet over LMDS:

architecture and experimental implementation,” IEEE Communications Magazine, vol 39,

pp 126-132, 2001

[8] S Ohmori, Y Yamao, and N Nakajima, “The future generations of mobile communications based on broadband access technologies,” IEEE Communications Magazine vol 38, no 12,

pp 134-142, 2000

[9] J Zander, “Radio resource management in future wireless networks: requirement and

limitations,” IEEE Communications Magazine, vol 35, no 8, pp 30-36, 1997

[10] T Ihara, and K Fujumura, “Research and development trends of millimetre-wave

short-range application systems,” IEICE Trans Commun., vol E 79-B, no 12, pp 1741-1753,

1996

[11] D Wake, D Johansson, and D G Moodie, “Passive pico-cell—New in wireless network

infrastructure,” Electron Lett., vol 33, pp 404-406, 1997

[12] D Novak, G H Smith, C Lim, A Nirmalathas, H F Liu, and R Waterhouse, “Optically fed millimeter-wave wireless communications," Proc Conference on Optical Fiber Communication (OFC'98), Washington DC, USA, vol 2, pp 14, 1998

[13] C Lim, A Nirmalathas, D Novak, R S Tucker, and R Waterhouse, “Wavelength- Interleaving Technique to Improve Optical Spectral efficiency In MM-wave WDM Fiber

radio” Lasers and Electro-Optics Society (LEOS ‘01), The 14th Annual Meeting of the IEEE,

San Diego, CA, USA vol 1, pp 54 –55, 2001

[14] C Lim, A Nirmalathas, D Novak, R S Tucker, and R Waterhouse, “Technique for increasing optical spectrum efficiency in millimeter wave WDM fiber-radio,” Electron Lett , vol 37, pp 1043 –1045, 2001

[15] H Toda, T Yamashita, K Kitayama, T Kuri, “A DWDM MM-Wave Fiber Radio system

by optical frequency interleaving for high spectra efficiency,” IEEE Top Meet On Microwave Photonics (MWP '01), pp 85-88, 2001

[16] K Kitayama, A Stöhr, T Kuri, R Heinzelmann, D Jäger, and Y Takahashi, "An Approach

to Single Optical Component Antenna Base Stations for Broad-Band Millimeter-Wave

Fiber-Radio Access Systems," IEEE Transactions on Microwave Theory and Techniques, vol.48,

no.12, pp.1745-1748, 2000

[17] L Noel, D.Wake, D G Moodie, D D Marcenac, L D.Westbrook, D.Nesset, “Novel

techniques for high-capacity 60-GHz fiber-radio transmission systems, IEEE Trans Microwave Theory Tech., vol 45, no 8, pp 1416-1423, 1997

[18] D Everitt, “Traffic capacity of cellular mobile communication systems,” Computer Networks and ISDN Systems, vol 20, pp 447-454, 1990

[19] M Berg, S Pettersson, and J Zander, “ A radio resource management concept for bunched

personal communication systems, “ Royal Institute of Technology,” Stockholm, 1997

[20] J park, and K Y Lau, “Millimetre-wave (39 GHz) fiber-wireless transmission of broadband

multichannel compressed digital video,” Electron Lett., vol 32, pp 474-476, 1995

[21] J J O'Reilly, “Performance considerations for MM-wave radio-over-fibre systems,” J of the Communications Research Laboratory, vol.46, no 3, pp 459, 1999

[22] R Heidemann, G Veith, “MM-wave photonics technologies for Gbit/s-wireless-local-loop,

“Proc Opto-Electronic Conference in Communications (OECC’98), Chiba, Japan, 1998

[23] U Gliese, “Coherent fiber-optic links for transmission and signal processing in microwave

and millimeter-wave systems,” Proc IEEE Top Meet on Microwave Photonics (MWP '98),

pp 211-214, 1998

[24] D Novak, G H Smith, C Lim, A Nirmalathas, H F Liu, and R Waterhouse, “Fiber-fed

millimeter-wave wirless system,” “Proc Opto-Electronic Conference in Communications (OECC’98), Chiba, Japan, 1998

[25] H Schmuck, R Heidemann, “Hybrid fiber-radio field experiment at 60 GHz,” Proc ECOC

1996, Oslo, pp 4.59-4.66, 1996

[26] C R Lima, D Wake, P A Davies, “Compact optical millimetre-wave source using a

dual-mode semiconductor laser,” Electron Lett., vol 31, no.5 pp 364-366, 1995

[27] J J O'Reilly, P M Lane, R Heidemann, R Hofstetter, “Optical generation of very narrow

linewidth millimetre wave signals,” Electron Lett., vol 28, no 25 pp 2309-2311, 1992

[28] T Kuri and K Kitayama, “60GHz band millimetre-wave signal generation and transport

over optical frequency division multiplexing networks,” Electron Lett., vol 32, pp

2158-2159, 1996

[29] K Kitayama, T Kuri, H Yokoyama, and M Okuno, "60 GHz millimeter-wave generation

and transport over OFDM fiber-optic networks," IEEE Top Meet on Microwave Photonics (MWP’96), Kyoto, Japan, TU3-5, 1996

[30] D Wake, and D Moodie, “Passive picocell-an unpowered remote transceiver for short range, high capacity radio systems,” IEE Colloquium on Fibre Optics in Microwave Systems and Radio Access, London, UK, pp 14/1-4, 1997

[31] D Wake, D Moodie, F Henkel., “The electroabsorption modulator as a combined photodetector /modulator for analogue optical systems” Workshop on High Performance Electron Devices for Microwave and Optoelectronic Applications (EDMO ’97), pp 147 –

150, 1997

[32] K.-A Persson, A Alping and D Wake, “WCDMA radio-over-fibre transmission experiment

using electro-absorption transceiver,” Electron Lett., vol 41, no 13, pp 764-766, 2005 [33] D Wake, L Noel, D G Moodie, D D Marcenac, L D Westbrook, D Nesset, “A 60 GHz

120 Mb/s QPSK fiber-radio transmission experiment incorporating an electro-absorption

modulator transceiver for a full duplex optical data path” IEEE MTT-S Int Microwave Symposium Digest, vol 1, pp 39-42, 1997

[34] D Wake, and D Moodie, “Passive picocell-prospects for increasing the radio range,” IEEE Top Meet on Microwave Photonics (MWP’98), Essen, Germany, pp 269-271, 1998

[35] L Noel, D Wake, D G Moodie, D D Marcenac, L D Westbrook, and D Nesset, “Novel

techniques for high-capacity 60 GHz fiber-radio transmission systems,” IEEE Trans Microwave Theory Tech., vol 45, pp 1416–1423, 1997

[36] L D Westbrook and D G Moodie, “Simultaneous bi-directional analog fiber-optic

transmission using an electroabsorption modulator,” Electron Lett., vol 32, no 19, pp

1806–1807, 1996

[37] L D Westbrook, L No¨el, and D G Moodie, “Full-duplex, 25 km analogue fiber transmission at 120 Mbytes/s with simultaneous modulation and detection in an

electroabsorption modulator,” Electron Lett., vol 33, no 8, pp 694–695, 1997

[38] Jager, D., A Stohr, and R Heinzelmann “Advanced microwave photonic devices for analog

optical links,” IEEE Top Meet On Microwave Photonics (MWP '98), Piscataway, NJ, USA

pp 153-156, 1998

[39] A Stohr, R Heinzelmann, and D Jager, “Microwave and millimetre-wave fibre optic links:

full-duplex fibre-wireless network architecture employing EA-transceiver,” Proceedings 10th MICROCOLL, Budapesti Muszaki Egyetem Memoktovabbkepzo Intezet, Budapest, Hungary,

pp.41-46, 1999

[40] A Stohr, K Kitayama, D Jager, “Full duplex fiber optic RF subcarrier transmission using a dual- function modulator/photodetector”, IEEE Trans Microwave Theory Tech., vol 47, pp

1338 –1341, 1999

[41] A Stohr, R Heinzelmann, and D Jager, “Millimetre-wave bandwidth electroabsorption

modulators and transceivers,” IEEE Top Meet On Microwave Photonics (MWP '00),

Piscataway, NJ, USA pp 125-128, 2000

[42] A Stoehr, R Heinzelmann, T Kuri, K Kitayama, D Jager, “Electroabsorption transceiver (EAT): device concepts and system applications,” Proc Int Soc Opt Eng (SPIE), USA, pp.314-316 2000

[43] K Kitayama, "An approach to single optical component antenna base station for broadband

millimeter-wave fiber-radio access system (Invited)," OIDA Microwave Phtonics Workshop,

Santa Monica, USA, 2000

[44] K Kitayama, T Kuri, R Heinzelmann, A Stöhr, D Jäger, and Y Takahashi, "A good prospect for broadband millimeter-wave fiber-radio access system - An approach to single

optical component at antenna base station (Invited)," Proc Microwave Symposium Digest, IEEE MTT-S, TH4C-3, vol 3, pp 1745-1748, 11-16 June, 2000

[45] T Kuri, K Kitayama, and Y Takahashi, "60-GHz-band full-duplex radio-on-fiber system

using two-RF-port electroabsorption transceiver," IEEE Photonics Technol Lett, vol 12, no

4, pp 419-421, 2000

[46] K Kitayama, K Ikeda, T Kuri, A Stohr, and Y Takahashi, “Full duplex demonstration of

single electro-absorption transceiver base station for mm-wave fiber radio system,” IEEE Top Meet On Microwave Photonics (MWP '01), pp 73 –76, 2001

[47] N Dagli., “Wide-bandwidth lasers and modulators for RF Photonics,” IEEE Trans, Microwave Theory Tech., vol 47, pp 1151-1171, 1999

[48] T Ido, S Tanaka, M Suzuki, M Koizumi, H Sano, and H Inoue, “Ultra high-speed multiple

quantum well electro-absorption optical modulators with integrated waveguides,” J Lightwave Technol., vol 14, pp 2026-2034, 1996

[49] A Nirmalathas, C Lim, D Novak, R Waterhouse, “Progress in Millimeter-Wave

Fiber-Radio Access Networks,” Annals of Telecommunications, vol 56, pp 27-38, 2001

[50] U Gliese, S Norskov, and T N Nielsen, “Chromatic dispersion in fiber-optic microwave

and millimeter-wave links,” IEEE Trans Microwave Theory Tech., vol 44, no 10, pp

1716-1624, 1996

[51] H Schmuck, “Comparison of optical millimetre-wave system concepts with regard to the

chromatic dispersion,” Electron Lett., vol 31, pp 1848-1849, 1995

[52] R A Griffin, P M Lane, and J J O’Reilly, “Dispersion-tolerant subcarrier data modulation

of optical millimeter-wave signals,” Electron Lett., vol 32, no 24, pp 2258-2260, 1996 [53] G H Smith, D Novak, and Z Ahmed, "Technique for optical SSB generation to overcome dispersion penalties in fiber-radio systems," Electron Lett., vol 33, pp 74-75, 1997

[54] G H Smith, D Novak, and Z Ahmed, “Overcoming chromatic dispersion effects in

fiber-wireless systems incorporating external modulators,” IEEE Trans Microwave Theory Tech.,

vol 45, no 8, pp 1410-1415, 1997

[55] K Kitayama, T Kuri, K.Onohara, T.Kamisaka, K.Murashima, "Dispersion effects of FBG filter and optical SSB filtering in DWDM millimeter-wave fiber-radio systems," J Lightwave Technol., vol 20, pp 1397-1407, 2002

[56] T Kuri, K Kitayama, A Stohr, and Y Ogawa, “Fiber-optic millimeter-wave downlink

system using 60 GHz-band external modulation,” J Lightwave Technol., vol.17, no 5, pp

[59] A Nirmalathas, D Novak, C Lim, R Waterhouse, “Wavelength Reuse in the WDM Optical

Interface of a Millimeter-Wave Fiber-Wireless Antenna Base Station,” IEEE Trans Microwave Theory Tech., vol 49, pp 2006-2012, 2001

[60] T Kuri, K Kitayama, and Y Takahashi, “Simplified BS without light source and RF local oscillator in full duplex millimeter-wave radio-on-fiber system based upon external

modulation technique,” IEEE Top Meet On Microwave Photonics (MWP '99), Piscataway,

NJ, USA, vol.1 pp.123-126, 1999

[61] L.T Nichols, and R D Esman, “Single sideband modulation techniques and applications,”

Proc Conference on Optical Fiber Communication (OFC'99), San Diego, CA, USA,

THW1-1, 1999

[62] G H Smith, D Novak, and C Lim, “A millimeter-wave full-duplex WDM/SCM fiber-radio

access network,” Proc Conference on Optical Fiber Communication (OFC'98), Washington

DC, USA, vol 2, pp 18-19, 1998

[63] R A Griffin, P M Lane, and J J O’Reilly, “Radio-over-fiber distribution using an optical

millimeter-wave/DWDM overlay,” Proc Conference on Optical Fiber Communication and the International Conference on Integrated Optics and Optical Fiber Communications (OFC/IOOC'99),San Diego, CA, USA, vol 2, pp 70-72, 1999

[64] K Kojucharow, M Sauer, H Kaluzni, D Sommer, and C G Schaffer, “Experimental investigation of WDM channel spacing in simultaneous upconversion millimeter-wave fiber

transmission system at 60 GHz-band,” IEEE MTT-S Int Microwave Symposium Digest,

vol.2, pp 1011-1012, 2000

[65] M A Al-mumin and G Li, “WDM/SCM optical backbone for 60 GHz wireless systems,” Proc IEEE Top Meet on Microwave Photonics (MWP2001), Long Beach, CA, USA, pp

61-64, 2001

[66] C Marra, A Nirmalathas, C Lim, D Novak, B Ashton, L Poladian, W S T Rowe, T Wang, and J A Besley, “Wavelength-interleaved OADMs incorporating optimized multiple

phase-shifted FBGs for fiber-radio systems,” J Lightwave Technol., vol 21, pp 32-39, 2003 [67] C Marra et al., “OADM with a multiple phase-shifted FBG for a wavelength-interleaved millimeter-wave fiber-radio system,” Optical Fiber Communication Conference (OFC’02),

pp 413-415, 2002

[68] H Toda, T Yamashita, K Kitayama, T Kuri, “Demultiplexing using an arrayed-waveguide grating for frequency-interleaved DWDM radio-on-fiber systems with 25-GHz channel

spacing,” Proc Int Soc Opt Eng (SPIE), vol 4906, USA, pp 99-106, 2002

[69] H Toda, T Yamashita, T Kuri, K I Kitayama,, “Demultiplexing using an waveguide grating for frequency-interleaved DWDM millimeter-wave radio-on-fiber

arrayed-systems,” J Lightwave Technol., vol 21, pp 1735-1741, 2003

[70] M Bakaul, A Nirmalathas, and C Lim, “Dispersion Tolerant Novel Base Station Optical Interface for Future WDM Fiber-Radio Systems,” Proc of Conference on Optical Internet/ Australian Conference on Optical Fiber Technology (COIN/ACOFT’03), pp 683-686, 2003 [71] M Bakaul, A Nirmalathas, and C Lim, “Multifunctional WDM optical interface for millimeter-wave fiber-radio antenna base station,” Journal of Lightwave Technol., vol 23,

no 3, pp 1210-1218, 2005

[72] A Nirmalathas, C Lim, M Attygalle, D Novak, R Waterhouse, and M Bakaul, "Recent

progress in fiber-wireless networks: Technologies and architectures" Proc ICOCN2003,

Bangalore, India, Oct 2003 (invited)

[73] M Bakaul, A Nirmalathas, and C Lim, “Experimental verification of cascadability of WDM

optical interfaces for DWDM Millimeter-wave fiber-radio base station,” IEEE Top Meet On Microwave Photonics (MWP '04), pp 169 –172, 2004

[74] A Loayssa, C Lim, A Nirmalathas, and D Benito, “Optical single-sideband modulator for

broad-band subcarrier multiplexing systems," IEEE Photon Technol Lett (PTL), vol 15, no

2, pp 311-313, 2003

[75] A Loayssa, D Benito, and M J Garde, “Single-sideband suppressed-carrier modulation

using a single-electrode electrooptic modulator,” IEEE Photon Technol Lett (PTL), vol 13,

no 8, pp 869-871, 2001

[76] A Loayssa, C Lim, A Nirmalathas, and D Benito, “Design and performance of the

bidirectional optical single-sideband modulator,” J Lightwave Technol., vol 21, no 4, pp

1071-1082, 2003

[77] R D Esman and K J Williams, “Wideband efficiency improvement of fiber optic systems

by carrier subtraction,” IEEE Photon Technol Lett., vol 7, no 2, pp 218-220, Feb 1995

[78] K J Williams and R D Esman, “Stimulated Brillouin scattering for improvement of

microwave fiber-optic link efficiency,” Electron Lett., vol 30, pp 1965-1966, 1994

[79] M R Phillips, D M Ott, “Crosstalk due to optical fiber nonlinearities in WDM CATV

lightwave systems,” J Lightwave Technol., Vol.17, pp.1782-1791, 1999

[80] L Cheng, S Aditya, Z Li, A Alphones and M Ong, “Nonlinear distortion due to XPM in

dispersive WDM microwave fiber-optic links with optical SSB modulation,” International Topical Meeting on Microwave Photonics, MWP, 2005

[81] G P Agrawal, Fiber-Optic Communication Systems, 3rd ed (Wiley, New York, 2002);

Greek Translation, 2000