Demonstration of ultrafast, all-optical, low control energy, single wavelength, polarization independent, cascadable, and integratable switch

Abstract

A new type of ultrafast all optical switch based on a Mach–Zehnder interferometer is demonstrated with a 10 ps switching window which requires only 0.65 pJ of control pulse energy. The optical nonlinearity which is utilized is associated with the gain compression of semiconductor optical amplifiers, and the switching turnoff transition does not depend on the slow amplifier recovery time. Both data and control pulses are at the same wavelength of 1.313 μm, and are not polarized orthogonal to each other. The device configuration and the semiconductor amplifiers allow for small scale integration and data output cascadability.

All-optical space switches with gain and principally ideal extinction ratios

“…It holds for traveling wave amplifiers, which ideally should be used in the all-optical switches. The second equal sign goes back to the definition of the alpha-factor which is the ratio of the refractive index change and the gain change (3) where is the wavelength of the data signal and the effective refractive index change which determines the total phase change through . The alpha-factor is a material constant depending on the wavelength, the current density, and the material used for the SOA's.…”

“…SOA's have been used in fiber loops [1] and in Mach-Zehnder interferometer (MZI) configurations. MZI's with optical nonlinearities, both passive [2] and active (MZI-SOA) [3] have demonstrated picosecond speeds. An advantage of the MZI-SOA version is that it allows for monolithic integration rendering the switches stable and compact [4], [5].…”

“…The high-speed capabilities are based on the fast carrier depletion times, whereas the carrier relaxation times are a limiting parameter. Ways to overcome this limit were found by operating with two control pulses [2], [6] or by spatially displacing the SOA's [3], [5]. However, in symmetric configurations, the on-off ratios in the nonswitched state and in the switched state are not equal.…”