the output optical emission, while Fig. 8.26 presents the experimental block diagram
of formation and transmission of the RF signal with the carrier of 60 GHz and the
modulation bandwidth of 1 GHz. As we see, the structure in Fig. 8.26 has OEO with
the direct QWLD modulation [11]. The central wavelength is 1.55 μm in Fig. 8.25,
experimental spectra of optical emission at output of LD 1 (c) and at output of the
optical filter (d) in OEO with the frequency 30 GHz (Fig. 8.25). The central
wavelength is 1.55 μm. The modulation frequency is 30 GHz. Before the optical
filter, the levels of optical components are À25 dBm, 5 dBm,À25 dBm. After optical
filter these levels are À17 dBm,12 dBm, 8 dBm.
An analysis of experimental results shows the OEO utilization (the average
generation frequency is 30 GHz) with the QWLD direct modulation allows not
only obtaining of low value of PSD of phase noise À100 to À110 dB/Hz at offset of
10 kHz (at average generation frequency 60 GHz), but achieving of the high-quality
oscillation transmission from the central station to the basing station on the distance
of more than 10 km through the fiber-optical communication link.
8.6 Conclusions
We make the general conclusion about promising utilization of QWLD as the
modulated light source in OEO in microwave range on the generation frequencies
of 8–15 GHz. We offer to use OEO with RF FODL in microwave and mm-wave
ranges in onboard of usual stations and the optical radar stations.
As the results of fulfilled experimental investigations of RF and microwave
ranges, the following conclusions are made.
On the base of studying of differential modulation characteristics U(θ,I bias ) and
Δφ(θ,I bias ) during emission pattern scanning for different samples of laser diodes,
Fig. 8.22 Variation of generated frequency at misalignment of the optical connector ОC 3 (а). The
amplitude characteristics of the piezoelectric sensor for the resonance frequency of 5 kHz of
acoustic influences (b)
500
8 Experimental Investigations and Practical Circuits of Optoelectronic. . .
of formation and transmission of the RF signal with the carrier of 60 GHz and the
modulation bandwidth of 1 GHz. As we see, the structure in Fig. 8.26 has OEO with
the direct QWLD modulation [11]. The central wavelength is 1.55 μm in Fig. 8.25,
experimental spectra of optical emission at output of LD 1 (c) and at output of the
optical filter (d) in OEO with the frequency 30 GHz (Fig. 8.25). The central
wavelength is 1.55 μm. The modulation frequency is 30 GHz. Before the optical
filter, the levels of optical components are À25 dBm, 5 dBm,À25 dBm. After optical
filter these levels are À17 dBm,12 dBm, 8 dBm.
An analysis of experimental results shows the OEO utilization (the average
generation frequency is 30 GHz) with the QWLD direct modulation allows not
only obtaining of low value of PSD of phase noise À100 to À110 dB/Hz at offset of
10 kHz (at average generation frequency 60 GHz), but achieving of the high-quality
oscillation transmission from the central station to the basing station on the distance
of more than 10 km through the fiber-optical communication link.
8.6 Conclusions
We make the general conclusion about promising utilization of QWLD as the
modulated light source in OEO in microwave range on the generation frequencies
of 8–15 GHz. We offer to use OEO with RF FODL in microwave and mm-wave
ranges in onboard of usual stations and the optical radar stations.
As the results of fulfilled experimental investigations of RF and microwave
ranges, the following conclusions are made.
On the base of studying of differential modulation characteristics U(θ,I bias ) and
Δφ(θ,I bias ) during emission pattern scanning for different samples of laser diodes,
Fig. 8.22 Variation of generated frequency at misalignment of the optical connector ОC 3 (а). The
amplitude characteristics of the piezoelectric sensor for the resonance frequency of 5 kHz of
acoustic influences (b)
500
8 Experimental Investigations and Practical Circuits of Optoelectronic. . .