Opto-Electronic Oscillator Circuit Working and Applications

1
Opto -Electronic Oscillator Circuit Operation and
Applications
2
Opto-Electronic Oscillator Circuit Operation and
Applications
Introduction

• The Opto-electronic oscillator circuit is
  comparable to the optoelectronic feedback
  circuits which are established by the Neyer and
  Voges in the 1982 year. In 1984 by Nakazawa and
  later on in the year 1992 by Lewis. The
  Opto-electronic oscillator is based on the
  converting continuous light energy from the pump
  laser to radio frequency, microwave or mm-wave
  signal.

http//www.elprocus.com/
3
Opto-Electronic Oscillator Circuit Operation and
Applications
What is an Opto-Electronic Oscillator?

• The Optoelectronic oscillator is an
  Opto-electronic circuit.
• The output of the circuit is in the form of the
  sine wave or modulated continuous wave signal. 
• It is a device where the phase noise of the
  oscillator does not increase the frequency.
• It is subject to the implementation of
  the electronic oscillators like crystal
  oscillator, dielectric resonator, and sir
  dielectric resonator.

http//www.elprocus.com/
4
Opto-Electronic Oscillator Circuit Operation and
Applications
Opto-Electronic Oscillator
http//www.elprocus.com/
5
Opto-Electronic Oscillator Circuit Operation and
Applications
Basic Operation of the OEO

• The following figure shows the operation of the
  Opto-electronic oscillator.

http//www.elprocus.com/
6
Opto-Electronic Oscillator Circuit Operation and
Applications
Basic Operation of the OEO

• By observing the circuit, the Optoelectronic
  oscillator starts with continuous wave laser is
  penetrating into the intensity modulator. 
• The output of optical intensity modulator is
  passed through a long optical fiber delay line
  and into a photodiode.
• The improved electrical signal is applied and
  approved through an electronic bandpass filter.

http//www.elprocus.com/
7
Opto-Electronic Oscillator Circuit Operation and
Applications
Basic Operation of the OEO

• To complete the Opto electronic cavity the output
  of the filter is connected to the RF input of
  intensity modulator.
• If the gain of the cavity is greater than the
  loss, then the optoelectronic oscillator is will
  start the oscillation. 
• The electronic band pass filter selects the
  frequency of the diminished the other free
  running modes of the cavity which is below the
  threshold.

http//www.elprocus.com/
8
Opto-Electronic Oscillator Circuit Operation and
Applications
Basic Operation of the OEO

• The OEO is different from the before
  Optoelectronic circuit by using the very low loss
  of the optical fiber delay line to produce a
  cavity with a huge high Q factor. 
• The Q factor is the ratio of the stored energy in
  the cavity over the loss of cavity.
• Thus the loss of the fiber delay line is in the
  order of the 0.2dB/ km with a less little loss a
  very long fiber is stored in a large amount of
  energy.

http//www.elprocus.com/
9
Opto-Electronic Oscillator Circuit Operation and
Applications
Basic Operation of the OEO

• Because of the Q factor, the OEO can achieve the
  level easily of 108.
• It can translate to 10GHz clock signal with a
  phase noise of 140 dBc/Hz at 10kHz offset.

http//www.elprocus.com/
10
Opto-Electronic Oscillator Circuit Operation and
Applications
Multi-Loop Opto-Electronic Oscillator

• The figure shows the dual loop Optoelectronic
  oscillator with the cavity mode within the band
  pass filter.

http//www.elprocus.com/
11
Opto-Electronic Oscillator Circuit Operation and
Applications
Multi-Loop Opto-Electronic Oscillator

• To achieve the high Q factor for the
  Optoelectronic oscillator there should be the
  maximum fiber length. 
• If the fiber length increases the space between
  the cavity modes will be decreased. 
• For an example, a 3 km length of the fiber will
  yield a cavity mode spacing of 67 kHz
  approximately. 

http//www.elprocus.com/
12
Opto-Electronic Oscillator Circuit Operation and
Applications
Multi-Loop Opto-Electronic Oscillator

• The high-quality electrical band pass filter is
  at 10GHz has 3dB bandwidth of 10MHz.
• Hence there will be many nonoscillating modes to
  continue through the electrical band pass filter.
• It can present in the phase noise measurement.
• There is another method to reduce this problem by
  second fiber length into the Opto-electrical
  oscillator. 

http//www.elprocus.com/
13
Opto-Electronic Oscillator Circuit Operation and
Applications
Multi-Loop Opto-Electronic Oscillator

• There will be the own set of cavity modes for the
  second loop of the OEO.
• If the length of the second loop is not a
  harmonic multiple of the first loop.
• Then the cavity modes will not overlap with each
  other.
• On the other hand the modes from each loop which
  are closest each other will lock and hold back
  the band pass the other cavity modes.

http//www.elprocus.com/
14
Opto-Electronic Oscillator Circuit Operation and
Applications
Single Loop Phase Noise Spectrum

• The single loop phase noise spectrum with the
  side modes next to the dual loop spectrum with
  the side mode suppressed below. 
• The exchange of the system is the phase noise.
• It is an average of the noise of the two loops
  independently.
• There is no phase noise just a long loop.

http//www.elprocus.com/
15
Opto-Electronic Oscillator Circuit Operation and
Applications
Single Loop Phase Noise Spectrum

• Hence, both the loops support the side modes and
  they are completely not eliminated, but they are
  suppressed.

http//www.elprocus.com/
16
Opto-Electronic Oscillator Circuit Operation and
Applications
Application of OEO

• The high-performance Optoelectric oscillator is a
  major element in many applications. Such as

• Aerospace engineering
• Satellite communication links
• Navigation systems.
• Precise meteorological time and frequency
  measurement
• Wireless communication links
• Modern radar technology

http//www.elprocus.com/
17
Opto-Electronic Oscillator Circuit Operation and
Applications
Conclusion

• The Opto-Electronic Oscillator is
  an optoelectronic circuit that produces
  repetitive electronic sine wave and/or modulated
  optical continuous wave signals. An
  opto-electronic oscillator is based on converting
  the continuous light energy from a pump
  laser to radio frequency (RF), microwave or mm-wav
  e signals.

http//www.elprocus.com/
18
http//www.elprocus.com/