Rafael C. Figueiredo

Hundred-Picoseconds Electro-Optical Switching With Semiconductor Optical Amplifiers Using Multi-Impulse Step Injection Current

An ultrafast electro-optical amplified switch based on chip-on-carrier semiconductor optical amplifier with high optical contrast (33 dB) is presented. Switching times up to 115 ps with small overshoot were achieved by using the multi-impulse step injected current technique. These results are compared with previous preimpulse step injected current technique, and achieve a reduction of the inherent, post switching gain fluctuations without worsening the switching times. In addition, pulse formats for controlling such a kind of electro-optical switches are numerically analyzed and compared with experiments.

Laser Linewidth and Phase Noise Evaluation Using Heterodyne Offline Signal Processing

A simple heterodyne scheme with digital data acquisition and offline signal processing is introduced to obtain phase noise spectra and linewidths of monomode lasers. The data are analyzed using time-domain memorized signals, enabling the evaluation of parameters such as coherence time, phase noise, laser linewidth as a function of bias current, and the identification of points where loss of coherence occurs. Results are presented for lasers with linewidths from 20 kHz up to 2 MHz.

Chip-on-carrier microwave mount for semiconductor optical amplifier measurements

The present paper describes a microwave mount (up to 40 GHz) with fiber facility inside an optical table for chip tests. Semiconductor optical amplifier (SOA) switching times of a chip-on-carrier (unpackaged) SOA were tested with rise times below 100 ps. It could be useful for a variety of SOA and photonic devices tests for electro-optical high-speed applications.

Equivalent circuit of a semiconductor optical amplifier chip with the bias current influence

Based on a diode-laser model, this paper presents the equivalent electrical circuit above and below the transparency condition for a chip (unpackaged) semiconductor optical amplifier. The modeling and parameters extraction were obtained as a function of the bias current, achieving good agreement between theoretical and experimental results in a wide frequency range, up to 40 GHz.

Remote instrumentation control and monitoring based on LabVIEW and SMS

Remote applications are becoming widely used in various fields such as industry, education, and security. This paper presents a low cost system to monitor and control laboratory instruments remotely by Short Message Service (SMS). The system has been designed using the National Instruments Laboratory Virtual Instrument Engineering Workbench (LabVIEW) development system. The user sends commands using a mobile phone remotely connected to a modem. The software recognizes the received code and transmits the command to the instrument. The system was successfully tested locally and remotely in a signal measurement procedure.

Frequency- and time-domain simulations of semiconductor optical amplifiers using equivalent circuit modeling

Abstract. We propose an equivalent circuit modeling for a chip-on-carrier and for two encapsulated semiconductor optical amplifiers (SOAs). The models include main parasitic leaks and were used in reflection and transmission simulations, showing good agreement with experimental data. The model for each SOA is validated, comparing the simulated results with experimental data from SOAs operating as high-speed electro-optical switches, reaching rise times below 200 ps.

Guard time requirements for SOA-based electro-optical space switches and AM signals

The transient and steady state performances of optical space switches based on semiconductor optical amplifiers (SOAs) switching an optical carrier modulated in amplitude through several switching techniques and operating parameters were characterized. The analysis was focused on the switchs guard time, resulting from the sum of its rise time and ringing time, and the switching amplitude, related with the modulated bits vertical opening when the switch is at on or off operating states and the switching pulse optical amplitude. The results point to the SOA optimum operating region, in relation to the analyzed parameters, which is defined by low bias current (between 60 mA and 80 mA) and high step amplitude (above 2 V).

Ultrafast Electro-Optical Switches Based on Semiconductor Optical Amplifiers

This chapter presents results from enhanced semiconductor optical amplifiers based switches to be employed on high-performance applications, which demand ultrafast transition times between operational states together with reduced guard times. A discussion on devices performance is accomplished through experimental characterizations of SOAs’ nonlinear properties and its oscillatory behavior. Switching techniques and mounting schemes are presented to improve switches’ dynamic operation, resulting in rise times below 200 ps and guard times of 650 ps. This performance, when combined with an improved energy efficiency, can offer a viable technical solution for switching in high-rates applications, such as Data Centers and supercomputers.

Multilevel Pulse Amplitude Modulation Transmissions for Data Center Applications

Four-level pulse amplitude modulation (PAM4) is appearing as an important option for many applications that require optical communications at high data rate for short distances and/or with low complexity, such as Data Center interconnects. In this sense, this chapter aims to evaluate key features requirements for PAM4 transmissions focusing on short-reach DC applications. Therefore, we present a software to emulate PAM4 transmission at a high baud rate (56 GBd) in order to evaluate different configurations and impairments that could affect data transmission in the C-band, namely the digital signal processing (DSP) complexity, bandwidth limitation, chromatic dispersion tolerance, differential group delay (DGD) tolerance, and analog-to-digital converter (ADC) sampling requirements.

Remote SMS Instrumentation Supervision and Control Using LabVIEW

The hot emergence of remote monitoring and control systems in recent years is closely related to the outstanding advance in electronics and instrumentation techniques. As one of the earliest examples, the telemetry experiments using satellite-relay systems for remote hydrologic data collection (Glasgow et al., 2004) in the 70’s should be remembered. Since then, a fast and continual appearance of real time monitoring systems occurred, new devices and tools have kept coming up, and more and more powerful resources are available with decreasing prices. Hence, remote monitoring and control systems are gaining market-share in diversified areas such as industry, security, education and even in health-care applications. In every distinct area it is possible to evince different advantages and applications when using remote systems. To exemplify the industrial field, a remote data acquisition may be used to monitor machine health and energy consumption in environments where it is difficult to access or to use wired data acquisition systems (Khan et al., 2004). As another example, a remote fault diagnostic system to check machines status including data, image, and video trough the Internet and mobile terminals by wireless application protocol (WAP) (Wang et al., 2007) was implemented. In the security area, a robot can inspect home environment giving general information and alarms about dangerous situations using wireless network (Zhang et al., 2007). In addition, real-time remote health monitoring systems can acquire and process data to evaluate long bridge structure reliability (Jianting et al., 2006). Regarding the educational field, there is a web-based remote control laboratory that employs a greenhouse scale model for teaching greenhouse climate control techniques using different hardware and software platforms (Guzman et al., 2005), and also a virtual laboratory that permits remote access via Transmission Control Protocol/Internet Protocol (TCP/IP), enabling control and supervision through the Internet (Garbus et al., 2006). In addition, the results of an evaluation of remote monitoring in home health care show a reduction in nursing visit and hospitalization rates in the remote monitoring patient group (Rosati, 2009). The example list can be much longer. The technological advances allow development of systems with more and better resources and higher transmission rates, consequently increasing its complexity and budget. However, in various applications we just need to