(based on FODL) of high-Q optoelectronic resonator of the “traveling wave” with
the loaded equivalent Q-factor of Q ¼ (0.2–0.8)Á10
6 in the frequency range
1–70 GHz.
This FODL consists of the series-connected quantum-well laser diode (QWLD)
with the external electro-optical modulator of Mach–Zehnder (MZ) (or QWLD with
direct modulation), the fiber-optical system (FOS) consisting of one or several
optical fibers and a photodetector (PD).
In OEO with QWLD and compact FODLs, we can obtain the low relative shortterm and long-term frequency instability of microwave oscillations of the order 10
À8
to 10
À11
. In this OEO, the generation frequency control can be performed by both
optical and RF means. OEO can be used with the great promise in classical radar
stations and in optical radars of new generation, in ultra-wideband regenerative
FODL as generators of ultrashort optical pulses and radio-pulse signal with duration
of 0.01–1 ps with the low “jitter” [21] (a random offset of the pulse leading edge), as
well as in FODLs, for information transmission in systems with increased confidentiality using the masking interference.
OEO utilization with such record characteristic in the radar technology allows us
the reliable determination of the small, hardly noticeable, and slow-moving targets
on the interference background at large distances. Utilization of compact radars for
UMFVs presents the special interest.
In the modern stage, the optoelectronic oscillator is a product of nanotechnologies. It uses the quantum-well (or nano-dimension) laser diodes, which have the
small phase noises and the high output power of optical emission (1–10 mW). The
optical fiber (OF) in miniature OEOs, is the special nanostructured fiber, which
allows the provision of the small OF bending radius (down to 1–5 mm) with low
optical losses per one bend (less than 0.001 dB).
We can say without overestimate that the appearance of commercially available
miniature optoelectronic oscillators with a walnut size will probably make the next
breakthrough in the radar technology, radio engineering, UMFVs, FODLs, and in
the mobile radio-telephony.
Nevertheless, this type of the promising OEOs is insufficiently theoretically and
experimentally studied at present. The main reasons of the ultralow phase noise
values are not explained for RF oscillation type at using in OEO with FODL of the
direct and external QWLD modulation type. In Russia, before 2004, none functioning laboratory sample of OEO (and an experimental breadboard) was developed in
the frequency range 2–12 GHz and above. In different countries, at the beginning of
2000s, with the appearance of commercial microwave electro-optical modulators,
the first experimental publications of Maleki and Steve Yao (Caltech) [22, 23] and
other researchers appeared concerning OEO investigations with external modulation
(using the electro-optical Mach-Zehnder modulator). In these publications, together
with successful experimental results on the phase noise PSD, the OEO theory with
fluctuations was not still formulated. It was not analyzed how the laser phase noise
(determined by its spontaneous noises) affects the RF phase noise in OEO as a
whole. A role of the laser phase noise [24] was not discussed in known publications
1 Introduction
3
the loaded equivalent Q-factor of Q ¼ (0.2–0.8)Á10
6 in the frequency range
1–70 GHz.
This FODL consists of the series-connected quantum-well laser diode (QWLD)
with the external electro-optical modulator of Mach–Zehnder (MZ) (or QWLD with
direct modulation), the fiber-optical system (FOS) consisting of one or several
optical fibers and a photodetector (PD).
In OEO with QWLD and compact FODLs, we can obtain the low relative shortterm and long-term frequency instability of microwave oscillations of the order 10
À8
to 10
À11
. In this OEO, the generation frequency control can be performed by both
optical and RF means. OEO can be used with the great promise in classical radar
stations and in optical radars of new generation, in ultra-wideband regenerative
FODL as generators of ultrashort optical pulses and radio-pulse signal with duration
of 0.01–1 ps with the low “jitter” [21] (a random offset of the pulse leading edge), as
well as in FODLs, for information transmission in systems with increased confidentiality using the masking interference.
OEO utilization with such record characteristic in the radar technology allows us
the reliable determination of the small, hardly noticeable, and slow-moving targets
on the interference background at large distances. Utilization of compact radars for
UMFVs presents the special interest.
In the modern stage, the optoelectronic oscillator is a product of nanotechnologies. It uses the quantum-well (or nano-dimension) laser diodes, which have the
small phase noises and the high output power of optical emission (1–10 mW). The
optical fiber (OF) in miniature OEOs, is the special nanostructured fiber, which
allows the provision of the small OF bending radius (down to 1–5 mm) with low
optical losses per one bend (less than 0.001 dB).
We can say without overestimate that the appearance of commercially available
miniature optoelectronic oscillators with a walnut size will probably make the next
breakthrough in the radar technology, radio engineering, UMFVs, FODLs, and in
the mobile radio-telephony.
Nevertheless, this type of the promising OEOs is insufficiently theoretically and
experimentally studied at present. The main reasons of the ultralow phase noise
values are not explained for RF oscillation type at using in OEO with FODL of the
direct and external QWLD modulation type. In Russia, before 2004, none functioning laboratory sample of OEO (and an experimental breadboard) was developed in
the frequency range 2–12 GHz and above. In different countries, at the beginning of
2000s, with the appearance of commercial microwave electro-optical modulators,
the first experimental publications of Maleki and Steve Yao (Caltech) [22, 23] and
other researchers appeared concerning OEO investigations with external modulation
(using the electro-optical Mach-Zehnder modulator). In these publications, together
with successful experimental results on the phase noise PSD, the OEO theory with
fluctuations was not still formulated. It was not analyzed how the laser phase noise
(determined by its spontaneous noises) affects the RF phase noise in OEO as a
whole. A role of the laser phase noise [24] was not discussed in known publications
1 Introduction
3