N. Finlayson

Third order nonlinear integrated optics

The authors review progress in the application of nonlinear optical phenomena to integrated optics. Essentially all integrated optics devices such as directional couplers, Mach-Zehnder interferometers, prism couplers, etc., can be used for all-optical signal processing when at least one of the waveguiding media exhibits an intensity-dependent refractive index. Experimental and theoretical results on the operating characteristics and figures of merit of such devices, as well as a new class of phenomena based on large nonlinear changes in waveguide properties will be summarized. Also discussed are measurement techniques for evaluating waveguide nonlinearities. Progress in the implementation of other nonlinear third order interactions, such as degenerate four-wave mixing and nonlinear spectroscopy, will also be reviewed. >

Picosecond switching induced by saturable absorption in a nonlinear directional coupler

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.

Optical nonlinearities in CdSxSe 1- x-doped glass waveguides

A pump–probe Mach–Zehnder interferometer was used to investigate the nonlinear-optical properties of CdSxSe1-x-doped glass channel waveguides. The technique is used in situ and may be used to determine the suitability of the material under investigation for all-optical switching. The saturation and dynamical properties of the material are readily determined by using the technique, as are thermal effects. Semiconductor-plasma theory was used to predict the nonlinear optical properties, and reasonable agreement with experiment was obtained.

Spatial switching, instabilities, and chaos in a three‐waveguide nonlinear directional coupler

A numerical study is conducted of a three‐waveguide nonlinear directional coupler. Markedly sharper transmittance characteristics than the well‐known two‐waveguide coupler are obtained at the expense of a higher switching power. Over longer distances transitions from quasi‐periodic to chaotic behavior and back take place as the power is varied.

All-optical switching in nonlinear X junctions

All‐optical switching in nonlinear X junctions with Kerr and saturable nonlinearities is analyzed using the beam propagation method. We establish that switching is possible in the nonlinear X junction, and compare its nonlinear phase shift requirements with that of other all‐optical devices.

Picosecond nonlinear polarization switching with a fiber filter

We report ultrafast all‐optical switching between two orthogonal linear polarizations in a periodically twisted, birefringent fiber filter.

Observation of ultrafast nonlinear polarization switching induced by polarization instability in a birefringent fiber rocking filter

Ultrafast all-optical switching between two orthogonal linear polarizations in a periodically twisted fiber filter is discussed. The dependence of the switching characteristics on the input power and operating wavelength is considered. >

Nonlinear-optical effects in ion-exchanged semiconductor-doped glass waveguides: erratum

We have measured nonlinear-optical effects in ion-exchanged channel waveguides fabricated in semiconductor-doped glass. The nonlinearity is manifested as optically induced saturable absorption displaying a resonant enhancement. The relaxation time of the nonlinearity was found to be tens of picoseconds. The relaxation time also exhibited wavelength dependence. Waveguide transmission and pulse-probe experiments using a picosecond mode-locked dye laser were used to carry out these measurements.

Beam propagation study of nonlinear coupling between transverse electric modes of a slab waveguide

The evolution of an optical field along a symmetrical slab waveguide capable of supporting two TE modes in the linear regime is investigated using the beam propagation method (BPM) where the waveguide and cladding media have a uniform, self‐focusing Kerr law nonlinearity. BPM calculations agree well with coupled‐mode theory at low input powers, but diverge at powers approaching the coupled‐mode value of the critical power and above, due to self‐focusing of the field. At high power, the beam splits into two parts which generate unusual long‐range collision effects.

All‐optical guided‐wave Mach–Zehnder switching device

We propose and analyze an all‐optical switching device on a nonlinear Mach–Zehnder waveguide interferometer. The nonlinear medium is modeled as a two‐level system to take saturation and attenuation effects into account.