The use of optically coherent detection techniques for true-time delay phased array and systems

We analyze a true-time-delay, optically controlled phased array antenna system whereby beam forming is accomplished using a large number of antenna elements that can receive any of several different microwave true-time-delays via the use of coherent optical carriers transmitted through a single fiber. The transmitter and receiver architectures are described in detail. We present calculations for the signal-to-noise ratio (SNR), the signal-to-interchannel interference ratio (SIR) and dynamic range (DR) of one channel for various modulation-demodulation schemes (i.e., AM-heterodyne, FM, PM). We show for an example system that can accommodate 128 antenna elements and provide 128 different delays (7 bits), assuming AM modulation with a bandwidth of 1 MHz, a transmitter power of -5 dBm and a laser linewidth of 10 MHz, we can obtain DR/spl sime/50 dB for one channel using a channel separation twelve times of that of the microwave frequency (f/sub m/). For the FM scheme, DR/spl sime/60 dB can be obtained for one channel with a laser linewidth of 1 MHz, a FM modulation index of one, and a channel spacing of about 13f/sub m/. With a local oscillator laser tuning range of 100 /spl Aring/, the system can provide seven-bit resolution for a 128 element antenna array. It is found that coherent optically controlled phased array antennas provide improved controllability over direct detection method, and can have the SNR, SIR and DR that meet the stringent requirements of modern high resolution microwave antenna systems. >

[1]  A. Mickelson,et al.  An optically driven phased array antenna utilizing heterodyne techniques , 1993 .

[2]  T. Durhuus,et al.  Detailed dynamic model for semiconductor optical amplifiers and their crosstalk and intermodulation distortion , 1992 .

[3]  Leonid G. Kazovsky,et al.  Linewidth-insensitive coherent optical analog links , 1992, Defense, Security, and Sensing.

[4]  Leonid G. Kazovsky,et al.  STARNET: A Multi-gigabit-per-second Optical LAN Utilizing a Passive WDM Star , 1993 .

[5]  A. Bruce Carlson,et al.  Communication Systems , 1968 .

[6]  S.R. Forrest,et al.  A coherent optically controlled phased array antenna system , 1993, IEEE Microwave and Guided Wave Letters.

[7]  Kazuhiro Oda,et al.  100 channel optical FDM technology and its applications to optical FDM channel-based networks , 1993 .

[8]  W. A. Stallard,et al.  Frequency-locking of external cavity semiconductor lasers using an optical comb generator , 1986 .

[9]  L. Kazovsky.  Multichannel coherent optical communications systems , 1987 .

[10]  Gregory L. Tangonan,et al.  System design and performance of a wideband photonic array antenna , 1994 .

[11]  Irwin L. Newberg,et al.  The first demonstration of an optically steered microwave phased array antenna using true-time-delay , 1991 .

[12]  R. Laming,et al.  Erbium-doped fiber amplifier with 54 dB gain and 3.1 dB noise figures , 1992, IEEE Photonics Technology Letters.

[13]  Stephen A. Pappert.  Ultra-Wideband Direction Finding Using A Fiber Optic Beamforming Processor , 1988, Photonics West - Lasers and Applications in Science and Engineering.

[14]  B. Kasper,et al.  Densely spaced FDM coherent star network with optical signals confined to equally spaced frequencies , 1988 .

[15]  H. Ishii,et al.  Over 1100 nm wavelength tuning in superstructure grating (SSG) DBR lasers , 1993 .

[16]  Gerhard A. Koepf,et al.  Optical Processor For Phased-Array Antenna Beam Formation , 1984, Other Conferences.

[17]  Willie W. Ng,et al.  GaAs and silica-based integrated optical time-shift network for phased arrays , 1994 .

[18]  D.J.M. Sabido,et al.  Linewidth-insensitive coherent AM analog optical links using semiconductor lasers , 1993, IEEE Photonics Technology Letters.

[19]  J. R. Wallington,et al.  Optical techniques for signal distribution in phased arrays , 1984 .

[20]  G. R. Walker,et al.  Optical amplifier noise figure in a coherent optical transmission system , 1990 .

[21]  Leonid G. Kazovsky,et al.  Impact of Laser Phase Noise on Optical Heterodyne Communication Systems , 1986 .

[22]  J. R. Forrest,et al.  The Use Of Optical Techniques For Beamforming In Phased Arrays , 1984, Other Conferences.

[23]  Ronald L. Johnson,et al.  Fiber Based Phased Array Antennas , 1987, Other Conferences.

[24]  Hiroshi Ishikawa,et al.  Extremely low-noise facet-reflectivity-controlled InGaAsP distributed-feedback lasers , 1986 .

[25]  Kazuro Kikuchi,et al.  Coherent Optical Fiber Communications , 1988 .

[26]  Simon Haykin,et al.  Array Processing: Applications to Radar , 1979 .