with environment power engineering equipment, the high noise-immunity, and
secrecy (electromagnetic compatibility).
Let us describe the block diagram of the laser Doppler radar (LDR) system on the
base of the optical phased antenna array (OPAA) (Fig. 8.18).
In the block diagram of Fig. 8.18a the following units are included: 1 ¼ the
powerful continuous-wave (or pulse) laser, 2 ¼ the external electro-optical microwave modulator of the laser emission intensity, 3 ¼ the electronic microwave driver,
4 ¼ the reference optoelectronic oscillator in the microwave range, 5 ¼ the transmitting optical antenna, 6 ¼ the receiving optical antenna, 7 ¼ the photoreceiver,
8 ¼ the microwave amplifier, 9 ¼ the processing unit, 10 ¼ the mixer, 11 ¼ the
system for laser beam guiding for spatial detection and guiding of the moving target.
To create the LDR on the native element base in the IR range with the operating
distance from 3 to 70 km and more, which have the microwave in the 25 GHz range
(in prospect in 50 GHz and higher), we can use the structure in Fig. 8.18b.
The following unit are included in the block diagram in Fig. 8.18b: 1—the
microwave phased array from laser diodes (continuous-wave or pulse) with the
direct internal modulation of their intensity, 2—the supply unit for laser diodes of
the array, 3—the divider of microwave power, 4—the powerful microwave driver,
5—the microwave preamplifier, 6—the reference optoelectronic oscillator, 7—the
noncoherent optical combiner-collimator of microwave-modulated of emission
intensity of laser diodes in the array, 8—the transmitting optical antenna (the lens
system), 9—the receiving optical antenna (the lens system), 10—the optical intensity
divider of received optical emission, 11—the receiving array from high-operationspeed photodiodes, 12—the unit of the bias voltage to receiving array photodiodes
(not always necessary), 13—the microwave amplifier of the photoreceiver, 14—the
microwave mixer, 15—the processing unit, 16—the system for laser beam pointing,
spatial detection and tracking of the moving target.
LDRs with the microwave subcarrier offered for development and implementation, allow measurements of target radial velocities in the real time scale and with
high accuracy at target and emitter movement in any direction. These measurements
can be performed owing to the large energy brightness of the high-intensity laser
quasi-continuous emission obtained at the output of the optical transmitter, as well as
owing to the high value of modulation frequency. Such laser Doppler radars are able
to measure of the small radial velocity of the moving targets of the order of 0.1 m/s
for large distance of 50 km and more, which becomes possible at the short-term
frequency instability of the order of 10
À10 to 10
À11 . Fulfillment of hard requirements
to the high-frequency oscillator in the transmitter and the to the microwave local
oscillator in the receiver concerning the short-term frequency instability is realizable,
when the quasi-harmonic OEO is applied with the unique transfer function of RF
FODL in the microwave loop of the positive feedback. Sensitivity and the dynamic
range of the LDR with the microwave subcarrier are higher by several orders than
characteristics of traditional Doppler radars because in LDR we provide measurement of the Doppler shift for subcarrier oscillations, which have high frequency
(10–25 GHz and higher) and the phase noise level is low: À130 to À150 dB/Hz. We
should note that the priority of the creation idea of the laser Doppler radar on the
8.5 Practical Circuits of the Optoelectronic Oscillator Implementation
493
secrecy (electromagnetic compatibility).
Let us describe the block diagram of the laser Doppler radar (LDR) system on the
base of the optical phased antenna array (OPAA) (Fig. 8.18).
In the block diagram of Fig. 8.18a the following units are included: 1 ¼ the
powerful continuous-wave (or pulse) laser, 2 ¼ the external electro-optical microwave modulator of the laser emission intensity, 3 ¼ the electronic microwave driver,
4 ¼ the reference optoelectronic oscillator in the microwave range, 5 ¼ the transmitting optical antenna, 6 ¼ the receiving optical antenna, 7 ¼ the photoreceiver,
8 ¼ the microwave amplifier, 9 ¼ the processing unit, 10 ¼ the mixer, 11 ¼ the
system for laser beam guiding for spatial detection and guiding of the moving target.
To create the LDR on the native element base in the IR range with the operating
distance from 3 to 70 km and more, which have the microwave in the 25 GHz range
(in prospect in 50 GHz and higher), we can use the structure in Fig. 8.18b.
The following unit are included in the block diagram in Fig. 8.18b: 1—the
microwave phased array from laser diodes (continuous-wave or pulse) with the
direct internal modulation of their intensity, 2—the supply unit for laser diodes of
the array, 3—the divider of microwave power, 4—the powerful microwave driver,
5—the microwave preamplifier, 6—the reference optoelectronic oscillator, 7—the
noncoherent optical combiner-collimator of microwave-modulated of emission
intensity of laser diodes in the array, 8—the transmitting optical antenna (the lens
system), 9—the receiving optical antenna (the lens system), 10—the optical intensity
divider of received optical emission, 11—the receiving array from high-operationspeed photodiodes, 12—the unit of the bias voltage to receiving array photodiodes
(not always necessary), 13—the microwave amplifier of the photoreceiver, 14—the
microwave mixer, 15—the processing unit, 16—the system for laser beam pointing,
spatial detection and tracking of the moving target.
LDRs with the microwave subcarrier offered for development and implementation, allow measurements of target radial velocities in the real time scale and with
high accuracy at target and emitter movement in any direction. These measurements
can be performed owing to the large energy brightness of the high-intensity laser
quasi-continuous emission obtained at the output of the optical transmitter, as well as
owing to the high value of modulation frequency. Such laser Doppler radars are able
to measure of the small radial velocity of the moving targets of the order of 0.1 m/s
for large distance of 50 km and more, which becomes possible at the short-term
frequency instability of the order of 10
À10 to 10
À11 . Fulfillment of hard requirements
to the high-frequency oscillator in the transmitter and the to the microwave local
oscillator in the receiver concerning the short-term frequency instability is realizable,
when the quasi-harmonic OEO is applied with the unique transfer function of RF
FODL in the microwave loop of the positive feedback. Sensitivity and the dynamic
range of the LDR with the microwave subcarrier are higher by several orders than
characteristics of traditional Doppler radars because in LDR we provide measurement of the Doppler shift for subcarrier oscillations, which have high frequency
(10–25 GHz and higher) and the phase noise level is low: À130 to À150 dB/Hz. We
should note that the priority of the creation idea of the laser Doppler radar on the
8.5 Practical Circuits of the Optoelectronic Oscillator Implementation
493