All-Optical Switch with Switch-Off Time Unrestricted by Carrier Lifetime
TL;DR: In this article, a symmetric Mach-Zehnder-type all-optical switch is proposed based on the nonlinear refractive index change induced in semiconductors.
Abstract: We propose a symmetric Mach-Zehnder-type all-optical switch which is based on the nonlinear refractive index change induced in semiconductors. Unlike most all-optical switches, the switch-off time, as well as the switch-on time, of this novel device is not limited by the usually slow carrier lifetime, allowing a very fast switching speed. Its switching characteristics are theoretically examined under various conditions. It is shown that the device offers a nearly square modulation characteristic that is suitable for most switching applications.
Citations
More filters
TL;DR: In this paper, the authors describe the way in which strongly modulated photonic crystals differ from other optical media, and clarify what they can do, including light confinement, frequency dispersion and spatial dispersion.
Abstract: Recently, strongly modulated photonic crystals, fabricated by the state-of-the-art semiconductor nanofabrication process, have realized various novel optical properties. This paper describes the way in which they differ from other optical media, and clarifies what they can do. In particular, three important issues are considered: light confinement, frequency dispersion and spatial dispersion. First, I describe the latest status and impact of ultra-strong light confinement in a wavelength-cubic volume achieved in photonic crystals. Second, the extreme reduction in the speed of light is reported, which was achieved as a result of frequency dispersion management. Third, strange negative refraction in photonic crystals is introduced, which results from their unique spatial dispersion, and it is clarified how this leads to perfect imaging. The last two sections are devoted to applications of these novel properties. First, I report the fact that strong light confinement and huge light–matter interaction enhancement make strongly modulated photonic crystals promising for on-chip all-optical processing, and present several examples including all-optical switches/memories and optical logics. As a second application, it is shown that the strong light confinement and slow light in strongly modulated photonic crystals enable the adiabatic tuning of light, which leads to various novel ways of controlling light, such as adiabatic frequency conversion, efficient optomechanics systems, photon memories and photons pinning.
403 citations
TL;DR: In this paper, an error-free and pattern-independent wavelength conversion at 160 Gb/s was demonstrated using an optical bandpass filter (OBF) placed at the amplifier output.
Abstract: Error-free and pattern-independent wavelength conversion at 160 Gb/s is demonstrated. The wavelength converter utilizes a semiconductor optical amplifier (SOA) with a recovery time greater than 90 ps and an optical bandpass filter (OBF) placed at the amplifier output. This paper shows that an OBF with a central wavelength that is blue shifted compared to the central wavelength of the converted signal shortens the recovery time of the wavelength converter to 3 ps. The wavelength converter is constructed by using commercially available fiber-pigtailed components. It has a simple configuration and allows photonic integration.
214 citations
05 Nov 2007
TL;DR: In this article, a quantum-dot semiconductor optical amplifier with a gain of 25 dB, noise figure of 20 dBm, over the record widest bandwidth of 90 nm among all kinds of optical amplifiers, and also having a penalty-free output power of 23 dBm was realized by using quantum dots.
Abstract: This paper reviews the recent progress of quantum-dot semiconductor optical amplifiers developed as ultrawideband polarization-insensitive high-power amplifiers, high-speed signal regenerators, and wideband wavelength converters. A semiconductor optical amplifier having a gain of > 25 dB, noise figure of 20 dBm, over the record widest bandwidth of 90 nm among all kinds of optical amplifiers, and also having a penalty-free output power of 23 dBm, the record highest among all the semiconductor optical amplifiers, was realized by using quantum dots. By utilizing isotropically shaped quantum dots, the TM gain, which is absent in the standard Stranski-Krastanow QDs, has been drastically enhanced, and nearly polarization-insensitive SOAs have been realized for the first time. With an ultrafast gain response unique to quantum dots, an optical regenerator having receiver-sensitivity improving capability of 4 dB at a BER of 10-9 and operating speed of > 40 Gb/s has been successfully realized with an SOA chip. This performance achieved together with simplicity of structure suggests a potential for low-cost realization of regenerative transmission systems.
212 citations
NEC1
TL;DR: In this paper, a symmetric-Mach-Zehnder (SMZ)-type switch was used to achieve error-free all-optical wavelength conversion at 168 Gb/s, which is the highest repetition rate ever reported.
Abstract: Error-free all-optical wavelength conversion at 168 Gb/s, which is the highest repetition rate ever reported, has been achieved by using a symmetric-Mach-Zehnder (SMZ)-type switch. Low-power-penalty 84-Gb/s operation is also demonstrated. The push-pull switching mechanism of the SMZ switch enables such ultrafast operation based on cross-phase modulation associated with the carrier depletion in a semiconductor optical amplifier. The configuration of the delayed-interference signal-wavelength converter, which is a simplified variant of the SMZ switch, is used in this experiment.
190 citations
Cites background from "All-Optical Switch with Switch-Off ..."
...In achieving such ultrafast optical signal processing, the Symmetric-Mach–Zehnder (SMZ) all-optical switch family, including the original SMZ switch [1], the Polarization-Discriminating SMZ (PD-SMZ) switch [2], and the Delayed-Interference Signal-wavelength Converter (DISC) [3]–[5] is quite promising....
[...]
TL;DR: In this paper, the authors review requirements of ultrafast all-optical devices and recent progress in ultrafast light sources and switches based on either novel device principles or ultrafast phenomena in novel materials such as quantum-confined nanostructures.
Abstract: Future bandwidth demand in optical communication and signal processing systems will soon exceed 100?Gb?s?1 as is commonly forecasted from a throughput experience curve for communication systems. However, such systems cannot be realized without introducing ultrafast, all-optical devices, since existing optoelectronic and electronic devices and integrated circuits would not be able to function at a bit rate exceeding 100?Gb?s?1, because of the speed limit intrinsic to conventional semiconductor materials and devices. All-optical devices based on completely new principles, not being restricted by properties of existing materials and device principles, must be developed for the realization of ultrafast communication and signal processing systems. This paper reviews requirements of ultrafast all-optical devices and recent progress in ultrafast light sources and all-optical switches based on either novel device principles or ultrafast phenomena in novel materials such as quantum-confined nanostructures. Recent developments described here include mode-locked lasers and a variety of all-optical switches based on different phenomena including Mach?Zehnder interferometer structures, spin relaxation, intersubband transition, and ultrafast absorption recovery in organic thin films and semiconductor quantum dots. Some of the recent developments have already shown capability of basic functions such as ultrafast pulse generation and signal processing at the bit rate of 500?Gb?s?1 to 1?Tb?s?1. Technical challenges expected for the future are discussed in view of their applications in real systems.
184 citations
References
More filters
TL;DR: In this article, the first parallel operation of GaAs optical logic elements and bistable devices was reported using a picosecond pump and probe technique, which achieved uniform response in two spots.
Abstract: We report the first parallel operation of GaAs optical logic elements and bistable devices. Arrays up to 2×4 in size were operated using a picosecond pump and probe technique, while in the bistable mode we achieved uniform response in two spots. Crosstalk due to carrier diffusion became noticeable at separations of typically ∼20–30 μm in the bistable devices. Pulsed operation at 82 MHz allowed separations down to ∼10 μm limited only by diffraction. Efficient heat sinking in the pulsed array resulted in negligible heating even when continually operated for many minutes. All experiments were performed at room temperature.
26 citations