In order to enable optical systems to operate with a high degree of compactness and reliability it is necessary to combine large number of optical functions in small monolithic structures. A development, somewhat reminiscent of that that took place in Integrated Electronics, is now beginning to take place in optics. The initial challenge in this emerging field, known appropriately as "Integrated Optics", is to demonstrate the possibility of performing basic optical functions such as light generation, coupling, modulation, and guiding in Integrated Optical configurations. The talk will review the main theoretical and experimental developments to date in Integrated Optics. Specific topics to be discussed include: Material considerations, guiding mechanisms, modulation, coupling and mode losses. The fabrication and applications of periodic thin film structures will be discussed.

Integrated optics

Femtosecond optical pulse shaping and processing

Two-photon absorption can place a fundamental limitation on waveguide all-optical switching devices. We have derived a general criterion to describe this limitation that must be satisfied by all materials. As a specific example, we have experimentally evaluated this criterion for a lead-glass fiber.

Two-photon absorption as a limitation to all-optical switching.

Few-layer Bismuthene: Sonochemical Exfoliation, Nonlinear Optics and Applications for Ultrafast Photonics with Enhanced Stability

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. >

Third order nonlinear integrated optics

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.

Optical nonlinearities in CdSxSe 1- x-doped glass waveguides

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.

Picosecond switching induced by saturable absorption in a nonlinear directional coupler

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.

All‐optical switching in nonlinear X junctions

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. >

N. Finlayson

Papers

Third order nonlinear integrated optics

Optical nonlinearities in CdSxSe 1- x-doped glass waveguides

Picosecond switching induced by saturable absorption in a nonlinear directional coupler

All‐optical switching in nonlinear X junctions

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