chaotic oscillator creation of the RF and microwave ranges on the OEO base, and
secondly, there is a possibility to have the electronic and fiber-optical outputs in the
chaotic OEO, and thirdly, there as a possibility of the electronic and optical synchronization of chaotic oscillations in the transmitter and in the receiver. The block
diagram of the lengthy (more than 70 km) fiber-optical communication link with
masked message transmission with OEO as the chaotic oscillation source is shown in
Fig. 8.19 [9]. OEO in this system operates in the chaotic mode and is synchronized
on the optical communication by the external laser diode LD 2 using the directional
coupler DC 1 . OEO is formed by in series closed into a loop by the modulated light
source MLS, consisting of the laser diode LD and the external Mach–Zehnder
modulator, the light guide LG, the photodiode PD 1 , and the radio-frequency amplifier NA. Notably, that in this structure, the external Mach–Zehnder modulator acts as
the nonlinear element. The average frequency of radio-frequency subcarrier is
10 GHz. The frequency of the optical carrier is approximately 128 THz (the
wavelength of optical emission is 1.55 μm).
For informational message extraction in the receiving section, the optical signal is
divided with the help of the directional coupler X-OC2 and passes on photodiodes
PD2 and PD3. From the photodiode PD2, the RF signal passes to the first input of the
mixer М 1 . The signal from the PD4 output passes to the second input of the СМ 1
mixer. The signal of original information message is extracted at the output of the
СМ1 mixer. Application of the nonlinear processing of the chaotic signal with delay
is a peculiarity of the structure of the secretive RF FODL. This signal channel
contains of the additional laser diode LD3, the modulator MZ2, and the photodiode
PD4.
Fig. 8.19 The block diagram of fiber optical communication link with masking message transmission with OEO as the chaotic source
8.5 Practical Circuits of the Optoelectronic Oscillator Implementation
495
secondly, there is a possibility to have the electronic and fiber-optical outputs in the
chaotic OEO, and thirdly, there as a possibility of the electronic and optical synchronization of chaotic oscillations in the transmitter and in the receiver. The block
diagram of the lengthy (more than 70 km) fiber-optical communication link with
masked message transmission with OEO as the chaotic oscillation source is shown in
Fig. 8.19 [9]. OEO in this system operates in the chaotic mode and is synchronized
on the optical communication by the external laser diode LD 2 using the directional
coupler DC 1 . OEO is formed by in series closed into a loop by the modulated light
source MLS, consisting of the laser diode LD and the external Mach–Zehnder
modulator, the light guide LG, the photodiode PD 1 , and the radio-frequency amplifier NA. Notably, that in this structure, the external Mach–Zehnder modulator acts as
the nonlinear element. The average frequency of radio-frequency subcarrier is
10 GHz. The frequency of the optical carrier is approximately 128 THz (the
wavelength of optical emission is 1.55 μm).
For informational message extraction in the receiving section, the optical signal is
divided with the help of the directional coupler X-OC2 and passes on photodiodes
PD2 and PD3. From the photodiode PD2, the RF signal passes to the first input of the
mixer М 1 . The signal from the PD4 output passes to the second input of the СМ 1
mixer. The signal of original information message is extracted at the output of the
СМ1 mixer. Application of the nonlinear processing of the chaotic signal with delay
is a peculiarity of the structure of the secretive RF FODL. This signal channel
contains of the additional laser diode LD3, the modulator MZ2, and the photodiode
PD4.
Fig. 8.19 The block diagram of fiber optical communication link with masking message transmission with OEO as the chaotic source
8.5 Practical Circuits of the Optoelectronic Oscillator Implementation
495