Lecture6 - Semiconductor Laser Amplifiers Erbium-Doped Fibre Amplifiers Integrated-Optic Devices EE4035 Optical Communications Semester A 2010-11

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Semiconductor Laser Amplifiers; Erbium-Doped Fibre Amplifiers; Integrated-Optic Devices EE4035 Optical Communications Semester A 2010-11 Lecture 6
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Intended Learning Outcomes (ILOs) Explain the operation principles of semiconductor laser amplifiers and calculate their characteristics. Explain the operation principle of erbium-doped fibre amplifiers and describe their characteristics and applications. Explain the operation principles of a range of optical waveguide devices. Analyze the characteristics of electro-optic waveguide modulators.
Background image of page 2
3 Optical Amplifiers Types of Optical Amplifiers: Semiconductor laser amplifiers (SLA) (Fabry-Perot Amplifier, Travelling wave amplifier) Optical fibre Amplifiers: Rare earth (Er 3+ ) doped fibre amplifier Raman fibre amplifier Brillouin fibre amplifier Semiconductor laser amplifiers exhibit low power consumption. Fibre amplifiers are more compatible with optical fibre links. Major concerns: Gain, output power, saturation, noise, crosstalk
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Semiconductor Laser Amplifiers w d L R 1 R 2 I bias Input Output Semiconductor Length of active region To reduce R 1 and R 2 , antireflection coatings or angled facets can be used. Fabry-Perot Amplifiers (FPA) Travelling-Wave Amplifier (TWSLA)
Background image of page 4
5 Semiconductor Laser Amplifiers Fabry-Perot Amplifier (FPA) The input and output laser facet reflectivities are each around 0.3. The transmission characteristic comprises very narrow passbands. The wavelength spacing between passbands δλ is given by = λ 2 / 2nL where n is the refractive index. For operation, the FPA is biased below the normal lasing threshold current. FPA is very sensitive to fluctuations in bias current, temperature, and signal polarization. Travelling-Wave Amplifier (TWSLA) The facet reflectivities are reduced to 1 × 10 3 or less. The device is therefore operated in the single-pass amplification mode. This has the effect of substantially increasing the amplifier spectral bandwidth and it makes the transmission characteristics less dependent on fluctuations in bias current, temperature, and signal polarization. In practice, the TWSLA is operated at a current far beyond the normal lasing threshold current.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Semiconductor Laser Amplifiers δ f Gain saturation effect Max gain ~ 30 dB Saturation power ~ 0 – 10 dBm Noise figure ~ 5 dB The dominant noise in SLAs is amplified spontaneous emission (ASE) .
Background image of page 6
7 Semiconductor Laser Amplifiers ( )( ) () φ 2 2 1 2 2 1 2 1 sin 4 1 1 1 ) ( s s s G R R G R R G R R f G + = Δ G Gain curve Cavity gain of a SLA:
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2011 for the course EE 4035 taught by Professor Prof.chiang during the Spring '10 term at City University of Hong Kong.

Page1 / 21

Lecture6 - Semiconductor Laser Amplifiers Erbium-Doped Fibre Amplifiers Integrated-Optic Devices EE4035 Optical Communications Semester A 2010-11

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online