Progress in Ultrafast Photonics

Abstract

Recent progress in ultrafast photonics is reviewed with special emphasis on the research and development activities in Japanese research institutions in the field of optical communication and related measurement technologies. After summarizing the physical natures of ultrashort optical pulses, selected topics are reviewed on such as (1) ultrahigh-bit-rate optical communication employing the combination of optical time division multiplexing (OTDM) and wavelength division multiplexing (WDM), (2) optical components for ultrafast photonics with emphasis on all optical switches including semiconductor optical amplifiers, cascaded second order frequency converters, semiconductor saturable absorber switches, organic dye saturable absorber switches and bistable semiconductor lasers, (3) microwave photonics, emphasizing millimeter-wave/photonic communication technologies, and (4) high-speed optical measurements featuring both compact femtosecond pulse source development and rf magnetic field imaging. Some comments on the future prospect of ultrafast photonics are also given. It is concluded that in order to bring the powerful and versatile capability of ultrafast photonics into the real world, further collaboration between photonics specialists and production engineers/information specialists is strongly desired.

Optical nonlinearity in glasses: the origin and photo-excitation effects

“…The 1P excitation occurs in proportion to the light intensity I, and extends to a penetration depth of ~α -1 from an illuminated surface. The 2P excitation is proportional to I 2 and the depth is given by (βI) -1 , which can produce peculiar excitation profiles, as already demonstrated in light manipulation and optical memories [2]. Figure 4 Schematic illustrations of (i) 1P bandgap, (ii) 1P sub-gap, (iii) 1P half-gap, and (iv) resonant 2P excitations in glasses.…”

“…For instance, optical fibers with large intensity-dependent refractive index n 2 and two-photon absorption coefficient β are required for all-optical switches and intensity stabilizers [2]. In addition, laser micro-fabrications appear to be indispensable for producing waveguides and three-dimensional devices [3,4].…”

Theoretical prediction of physical parameters of GexSb20−x Te80 (x = 11, 13, 15, 17, 19) bulk glassy alloys

“…In this context, chalcogenide glass and its dimensionality is a subject of intensive current research. Chalcogens have an important role in the field of optoelectronics [1], precision glass molding (PGM) [2], etc. Higher value of linear and non linear refractive index and substantial absorption in visible to NIR part of spectrum make them irreplaceable materials for mid-infrared sensing, integrated optics and ultrahigh-bandwidth signal processing.…”

High speed logic gate using two-photon absorption in silicon waveguides

“…The high optical intensities and long interaction lengths in the waveguides allow nonlinear optical effects to be readily apparent. Apart from other nonlinear optical devices such as optical fibers and SOA, silicon wire waveguides have good potential for other nonlinear devices for ultrafast photonics signal processing [8].…”

“…The high optical intensities and long interaction lengths in the waveguides allow nonlinear optical effects to be readily apparent. Apart from other nonlinear optical devices such as optical fibers and SOA, silicon wire waveguides have good potential for other nonlinear devices for ultrafast photonics signal processing [8].We demonstrated previously an ultrafast optical switch (<3 ps) with pJ pump pulse energy in wire waveguides [9,10]. In this paper, we develop a high speed all-optical logic NOR gate based on the nonlinear transmission characteristics of two-photon absorption (TPA) in silicon.…”