C.N. Ironside

Principles and applications of nonlinear optical materials

Nonlinear optical phenomena, C.N. Ironside and R.W. Munn nonlinear optical devices C.N. Ironside and R.W. Munn optical nonlinear effects in semiconductors, C.N. Ironside and R.W. Munn nonlinear glasses, J.S. Aitchison ferroelectric crystals, M. Ebrahimzadeh and A.I. Ferguson Molecular crystals, R.T. Bailey, et al polyners, G.H. Cross Langmuir-Blodgett films, P. Hodge and N. McKeown liquid crystals, H.J. Coles.

Ultrafast all‐optical switching in semiconductor nonlinear directional couplers at half the band gap

Efficient ultrafast all‐optical switching in nonlinear directional couplers made of AlGaAs and AlGaAs/GaAs quantum wells near half the band gap is reported. The switching is limited by multiphoton absorption which is dominated by three‐photon absorption in this spectral range. The three‐photon absorption in the quantum well nonlinear directional coupler is stronger than that of bulk AlGaAs. Autocorrelations of the output pulses in the bar and cross states confirm pulse breakup through nonlinear coupling, and illustrate the effects of multiphoton absorption. All sets of experimental data are fitted well by a theoretical model.

An all-optical switch employing the cascaded second-order nonlinear effect

A new, ultrafast, low loss, all-optical switch based on the cascaded second-order nonlinearity is proposed. The device is based on an integrated Mach-Zehnder interferometer where quasi-phase matching produces a nonlinear phase shift with a different sign in each arm of the interferometer. A full treatment of the nonlinear phase shift indicates that the proposed device, if fabricated in AlGaAs, could switch with powers around 1.3 W in a length of approximately 1 cm. >

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.

All-optical switching based on nondegenerate phase shifts from a cascaded second-order nonlinearity

All-optical switching by using a nondegenerate cascaded second-order nonlinearity is described wherein a phase shift is induced at one frequency owing to the presence of intense light at a different frequency. A Mach-Zehnder waveguide device is proposed to take advantage of this process and has applications for all-optical switching and demultiplexing, potentially at power levels near 10 W by using quasi-phase matching in semiconductor waveguides.

Monolithic multiple colliding pulse mode-locked quantum-well lasers, experiment and theory

We report here on a monolithic multisectioned quantum-well laser that operates as multiple colliding pulse mode-locking source. With this type of operation several pulses are present within a laser simultaneously and it produces high-repetition rate pulse trains (up to 375 GHz) and pulse techniques of around 1-3 ps, as deduced from linear correlation technique measurements. By changing the configuration of the sections 1, 2, 3, or 4 pulse operation can be selected; frequency- and time-domain theories have been developed to explain this type of behavior. >

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.

Effects of saturation and loss on nonlinear directional couplers

We show that large changes are introduced into the operational characteristics of nonlinear directional couplers by both loss and saturation of the nonlinearity, especially the latter. Specific numerical examples are given.

Semiconductor‐doped glass ion‐exchanged waveguides

The properties of planar waveguides and directional couplers fabricated by potassium/sodium ion exchange in semiconductor‐doped glasses are described.

Subpicosecond Pulse Generation at Quasi-40-GHz Using a Passively Mode-Locked AlGaInAs–InP 1.55-

We report on subpicosecond pulse generation using passively mode-locked laser diodes based on AlGaInAs 1.55-mum strained multiquantum-wells. Without any external pulse compression, the nearly transform-limited Gaussian pulses are generated at the quasi-40-GHz repetition rate with the 700-fs pulse duration.