New applications of a sinusoidally driven InGaAsP electroabsorptionmodulator to in-line optical gates with ASE noise reduction effect

The authors propose new applications of a sinusoidally driven InGaAsP electroabsorption modulator to an inline optical gate for a 2R (reshape and retiming) repeater in optical amplifier systems, an n :1 optical demultiplexer in time division multiplexing systems, and an optical switch. The small polarization dependence of the modulator is essential for inline use. By utilizing the monotonic increase of the extinction ratio with increasing applied voltage, the electroabsorption modulator driven by a large-signal sinusoidal voltage can produce a time domain square-shaped gate function with variable gate width. Furthermore, amplified spontaneous emission noise of optical amplifier systems can be reduced in both time and wavelength domains at the off-state of the modulator, due to noninterferometric wide wavelength operation of the modulator. Experimental results for a 2R repeater, an n:1 (n=4, 8) optical demultiplexer, and optical gates for switching are also demonstrated at over 10-Gb/s repetition rate