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Vertical cavity laser arrays are modeled using coupled rate equations. Experimental modulation response as a function of resonance detuning, phase, and field distribution is compared with theory and shows qualitative agreement. Biasing conditions and device design parameters are analyzed for enhanced modulation bandwidth.
In this paper we will discuss avenues to exploit the potential low loss and low linearity of hollow core photonic band gap fibres (HC-PBGF) at 2 microns wavelength. In particular, we will show recent developments in semiconductor devices to enable a 100Gbit/s transmission demonstration.
We propose a multi-band OFDM modulation for wireless VLC system together with dynamic bandwidth allocation. In addition, the proposed modulation format also can enhance the maximum VLC traffic rate to 17.8% without using blue filter.
The dynamics of C-band quantum-dot and quantum-dash lasers under small-signal modulation are compared. We show a strong influence of the density of states function on the cut-off frequency, being much higher for QDs at low currents, but reaching similar values for QDashes at higher currents.
Single-shot detection of a terahertz (THz) electric-field transient has been demonstrated using a high-bandwidth oscilloscope. The THz modulation was imprinted on a chirped picosecond probe pulse via an electro-optic crystal, and the probe pulse was subsequently temporally expanded to nanosecond time scales using the group velocity dispersion of a long optical fiber. The resulting GHz modulation on...
In this paper we present 1Gb/s wireless data reception at different sub-THz carrier wave frequencies, using a single quasi-optic Schottky receiver module. The module employs a Log-Spiral broadband antenna patterned on silicon. In this paper we present the performances at carrier wave frequencies ranging from 90 GHz to 330 GHz, demonstrating for the first time the flexibility of the module as versatile...
Aeronautical vehicle use, and consequently, air-to-ground communication systems, are growing rapidly. A growing portion of these vehicles are unmanned aerial vehicles (UAVs) or unmanned aerial systems (UAS) operating in civil aviation systems. As a consequence of this growth, air traffic volume for these vehicles is increasing dramatically, and it is estimated that traffic density will at least double...
A stability-improved single operational amplifier third-order ΣΔ modulator by using a fully-passive noise shaping SAR ADC as a quantizer is presented in this paper. One operational amplifier is shared to realize 2nd order noise shaping and an additional 1st order noise shaping is realized by a fully-passive technique in the quantizer. An additional switch and capacitor path is introduced to the operational...
A noise-efficient readout interface designed in a 150nm standard CMOS technology for a FET based THz radiation detector is presented. The interface is able to detect μV-range rectified signal from the FET detector, amplifying it by 70 dB gain. A multistage switched-capacitor (SC) readout channel employing chopper modulation is exploited so as to remove 1/ƒ noise and obtain repeatable gain and frequency...
This paper presents a reconfigurable SC audio ΣΔ modulator implemented in a 0.18-mm CMOS technology. The 0.4-mm2 ΣΔ modulator, based on a 2-2 MASH architecture, features several different operating modes in which noise-shaping order, number of output bits, sampling rate, and signal bandwidth can be programmed. The power consumption is always minimized for the selected operating mode. The achieved...
A continuous-time ΔΣ ADC with a new high-linearity Gm-cell is presented. A loop filter employing a Gm-C filter is preferable to an active-RC filter with op-amps for low power consumption and a large phase margin. However, distortion caused by the Gm-cell degrades the ADC performance. A cascoded flipped voltage follower Gm-cell is proposed in order to address this problem. Simulation results reveal...
In this paper, dynamic resource allocation and multicast routing algorithms are proposed for elastic optical networks (EONs). The proposed algorithms find the shortest path trees by modeling either the amount of free spectrum in each link or the link length as the cost function of routing method. The proposed algorithms are simulated in the dynamic operation scenario over the so called US Backbone...
A flexible data retrieval service is needed in data center networks, where erasure coding has been widely adopted. Elastic Optical Networks, based on Nyquist wavelength division multiplexing or optical orthogonal frequency division multiplexing is an ideal backbone for data centers, since they can efficiently utilize the optical fiber's bandwidth in an elastic manner by partitioning the bandwidth...
A balanced modulator/amplifier which uses saturated short channel (1μm) NMOS transistors to achieve low distortion is described. Operated with a 5V power supply, the circuit has a gain of 10, 3dB bandwidth near 100MHz, and nonlinearity less than 0.5% for a differential output amplitude of 4V P-P.
A multimode 850-nm VCSEL with its relative-intensive-noise suppressed to −145 dBc/Hz is employed for directly encoded 56-Gbps 16-QAM OFDM and 22-Gbps PAM-4 transmissions with corresponding BERs of 3.2×10−3 and 1.9×10−10, respectively.
We fabricated a lumped-electrode type EADFB laser module using a flip-chip interconnection technique which provides a large modulation bandwidth. We obtained clear 56-Gbaud 4-PAM signal after 10-km SMF transmission with no equalizer using this module.
We reported a real-time single carrier 400Gb/s system with baud rate of 61GHz. The reality challenges and corresponding DSP solutions are discussed. We show back-to-back as well as propagation performance of the system.
For the first time, bandwidth-efficient iOÖ+G/λ IMDD optical links based on Nyquist 256QAM is proposed and demonstrated. With innovative fast-converging blind equalization and nonlinearity compensation algorithms, 160-Gbps gross line rate over 2-km SMF is achieved.
We propose a novel low-cost, spectrum efficient mobile fronthaul architecture for spatial densification. For the first time, bi-directional mobile data services following 3GPP release-12/13 standards are delivered using only low-cost colorless WRC-FPLDs in RRHs.
We demonstrate an ultra-short cavity 1.5-μm single-mode directly-modulated VCSELs with record modulation bandwidth of 22 GHz at room temperature operation.
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