光电子材料导论第一章 信息处理技术和材料-全光波长转换 (2)演示教学

The most important use will be for avoidance of wavelength blocking in optical cross connects in WDM networks.
Increase the flexibility and the capacity of the network for a fixed set of wavelengths.
The XGM SOA wavelength converter is polarization independent.
Long SOA has superior dynamic performance
Long SOA only has 30 nm bandwidth, whereas it is 60 nm for short SOA.
Smaller bandwidth gives larger differential gain at the short wavelength side of the gain peak, a larger extinction ratio of the converted signal is expected for the long SOA
Incorporating saturable absorbers, injection locked Y-lasers; FWM in optical fiber.
XG saturation characteristic.
A cw signal at the desired output wavelength is modulated by the gain variation, so after the SOA it carries the same information as the intensity modulated input signal.
All-optical wavelength converters:
Semiconductor optical amplifiers(SOA) in cross gain modulation (XGM)
Cross phase modulation (XPM), Four wave mixing (FWM), bistable lasers
Critical next step in the evolution of optical networks and photonic packet switching.
World's first widely-tunable all-optical wavelength converter, designed and fabricated at UCSB
achieved by strong phonon
prepared by the intense
secondary pump wave P2
and the corresponding first
Stokes wave S1(P2).
Schematic diagram of dual-wavelengthpumped fiber Raman converter.The P1 wave is incident on the converter fiber, and the P2 and S1(P2) waves are also incident on the converter fiber from fiber couplers. Then, FWM occurs in the converter due to Raman polarization and generates a S1(P1) wave while maintaining the original information in the P1 wave. The wavelength of the converted S1(P1) wave is varied by adjusting the S1(P2) wavelength.
Extinction Ratio of XGM-converted Signals
XPM SOA Converters
XPM
Schematic of monolithic integrated asymmetric MZI-SOA wavelength converter
四波混频全光波长转换
Energy-level diagram for
dual-wavelength-pumped
Raman-resonant
FWM
process. Conversion of the
weak primary pump wave P1
to the corresponding first
Stokes wave S1(P1) is
Wavelength conversion technologies
Electro-optic converter consisting of a detector followed by a laser that retransmits the incoming signal on the new wavelength. Complexity Large power consumption Speed limitation
All-optical wavelength conversion
To “imprint” digital information from one wavelength of to another wavelength without passing the signal through electronics
• Large wavelength span for both input and output signals.
• Possibility for same input and output wavelengths (no conversion).
• Low chirp • Fast setup time of output wavelength • Insensitivity to input signal polarization • Simple implementation