Steady interest to oscillators in which chain of a feedback the fiber-optical optical path is used - is caused by their perspective applications for genera-tsii ultrashort optical impulses 1-100 пс and stable radio-frequency in a range from 0.1 MHz to 100 GHz. In the given oscillators working at o'clock a mode, named in works as laser generators with a compound fiber-optical line of a delay (OEO ) it is possible to realise system with a late feedback.
High good quality of system is provided with creation in the channel with a late feedback of the big time delay of a signal 5-40 mks, and also low losses of light in fiber optical paths to 0.01 Db/km.
Working out and use of the new broadband modulated light sources , optical modulators and photodetectors in self-oscillatory systems that of type has given the chance to achieve unifrequent generation with small level of phase noise on frequencies of generation from 1 to 50 GHz. Now in oscillators of this class level of phase noise on frequency of generation of 10 GHz - 134 Db/ Hz is experimentally reached at 1 kHz from radio-frequency bearing.
The potential frequency limit of such oscillators is limited to a strip of the photodetector and 600 GHz equal approximately. They can successfully compete in the field of a centimetric and millimetric range of lengths of waves with known avtogenera-torami on diodes Ghana to various types of dielectric resonators, etc.
Thanks to property OEO simultaneously to generate both radio-frequency and optical impulses 1ps- duration their use as functional converters in fiber-optical gauges and means OEO is represented highly profitable and perspective.
At present optical management methods are a little investigated by frequency of self-oscillations of such oscillators.
The purpose of the given work – to study ways of management of frequency of generation OEO at inclusion in its optical system fiber-optical directed from-vetvitelej Y - and X-types, and also to analyse influence of parametres of optical system on character of transients at an establishment of fluctuations.
Into the LOG enter consistently closed in a ring the modulated light source – the laser diode, fiber-optical system , the photodetector , the nonlinear electronic amplifier and the narrow-band radio-frequency filter . The sinusoidal radio signal arriving on an input of the laser diode, modulates optical radiation ЛД on intensity. In ВОС, formed two optical fiber optical paths carry out a delay of a light signal for average time. On a photodetector exit the radio signal with a current equal turns out. At passage of the nonlinear amplifier which has soft nonlinearity, the signal has strengthening with the advent of frequency making in its spectrum. At passage of the electronic filter of a harmonic above the first choke and on its exit it is had sinusoidal fluctuation detained on time. At observance of balance of amplitudes and phases in such system there are self-oscillations with frequency and amplitude.
The principle of management considered more low in OEO is based by frequency on inclusion in its fiber-optical part of two (or several) fiber optical paths, for example, ВС1 and ВС2 different length and, excitation factors on their inputs make accordingly A and B and have possibility to change.
The modulated light source in the presented scheme can be not only the laser diode, but also a light-emitting diode or an independent source of light radiation with external оптоэлектронным the modulator.
The described results theoretical and experimental researches to draw a conclusion that at construction reconstructed and stabilised on frequency OEO the choice of the scheme of construction taking into account application ответвителей Х – or Y-types is important. Management of frequency of fluctuations in the scheme OEO on the basis of Y is more expedient at use for management excitation A and B and internal parametres of fiber-optical system. The scheme on the basis of X needs to be used at management of frequency by means of a variation of optical frequency of a modulated light source. Thus on a spectrum of frequencies of generation OEO can make essential impact low-frequency and high-frequency modulations of the optical bearing.