Picosecond switching induced by saturable absorption in a nonlinear directional coupler

Abstract

Fluence-induced changes in absorption of a semiconductor-doped-glass directional coupler have resulted in nonlinear optical switching on a picosecond time scale. The functional dependence on the incident fluence confirms that the switching is dominated by absorption saturation.

Nonlinear Guided Wave Optics

“…Analytical solutions were first reported for Αβ = 0 by Maier and Jensen [58,59], and generalized later to Αβ Φ 0 by Wabnitz and Trillo [60], and by Maier and Sitarski [61]. Switching in nonlinear directional couplers (and their analogs) has been demonstrated in glass fibers [62][63][64], and in organic [28] and semiconductor [23][24][25][26][27]29] integrated optics waveguides. 9a.…”

All-optical Integrated Nonlinear Devices

“…Finlayson et al . [45] have observed electronic picosecond operation in the visible with channelwaveguides in CdSSe-doped glass, demonstrating the concept of switching due to nonlinear differential saturable-absorption . In their experiment, the two guides both saturated in absorption, but at different rates .…”

“…Unfortunately, this device places very stringent requirements on material properties [9,40], and there are only a few experimental reports [38,[41][42][43][44][45] . Most of these demonstrations of NLDC operation have been performed in the near infrared with GaAs-AlGaAs multiple quantum well (MQW) structures [40][41][42][43][44], where the observed nonlinear effects are probably electronic in nature and due to an excitonic resonance in the MQW .…”

Ion-exchanged glass waveguide technology: a review

“…130 An ion-exchanged directional coupler in such a glass was demonstrated with picosecond all-optical switching, but this was dominated by fast saturable absorption, so the switching fraction was not high. 131 The limitation was that these commercial glass types did not have optimal nonlinear properties, as the semiconductor nanocrystals in the glass did not have sufficient size distributions. More recently, silver-sodium and potassium-sodium ion-exchange waveguide fabrication was demonstrated in glasses doped with PbS quantum dots, which have high nonlinearities.…”