Mariko Sugawara

Lasing at three-dimensionally quantum-confined sublevel of self-organized In/sub 0.5/Ga/sub 0.5/As quantum dots by current injection

A laser oscillation from self-organized In/sub 0.5/Ga/sub 0.5/As quantum dots is achieved at 80 K by current injection. Lasing at a three-dimensionally quantum confined sublevel of the In/sub 0.5/Ga/sub 0.5/As quantum dots is clearly demonstrated for the first time by electroluminescence and diamagnetic energy shift measurement. The results predict the possibility of ultra-low threshold current operation of quantum dot lasers.

A Single-40 Gb/s Dual-20 Gb/s Serializer IC With SFI-5.2 Interface in 65 nm CMOS

This paper presents a 40 Gb/s serializer IC in 65 nm bulk CMOS technology. The IC has an SFI5.2-compliant 10 Gb/s input interface and supports two different output modes, single 40 Gb/s for OC-768 VSR and dual 20 Gb/s for DQPSK. The IC is evaluated on a PCB and error-free operation is confirmed. The chip consumes 1.8 W for the 40 G mode, and 1.6 W for the 20 G mode from 1.2 V and 3.3 V power supplies.

Regenerative Amplification by Using Self-Phase Modulation in a Quantum-Dot SOA

We experimentally demonstrate regenerative amplification of 10-, 20-, and 40-Gb/s return-to-zero signals exploiting a simple scheme based on self-phase modulation (SPM) in a columnar quantum-dot (CQD) semiconductor optical amplifier (SOA) and the use of a red-shifted off-set filter. We study the signal Q 2-factor improvement as a function of the input power to the amplifier. We also report results using a quantum-well (QW) SOA for comparison. We find that the SPM-based regenerative amplification is only possible in the quantum-dot amplifier.

8.9 A 40Gb/s VCSEL over-driving IC with group-delay-tunable pre-emphasis for optical interconnection

High-speed and high-density interconnections between racks and modules in the high-performance computing systems and data centers are currently being developed. The transmission range of conventional electrical interconnections is limited due to the bandwidth of electrical channels. VCSEL-based optical interconnection technologies are a promising solution for overcoming bandwidth bottlenecks in large scale computing systems [1-3]. Although it is anticipated that the next challenge for optical interconnections is to move to a serial data-rate of 40Gb/s, there are few 40Gb/s class VCSELs at present. Overdriving is a method that boosts high-frequency response to overcome the VCSEL speed limit [4,5]. To develop high-density optical interconnections, a low-power over-driving IC is a key technology. In addition, the optical modulation amplitude (OMA) must be increased to enable long-distance transmission in large scale computing systems as a data center. To achieve this large modulation amplitude, we must overcome the jitter issue caused by the intrinsic group delay of VCSELs. In this paper, we present a 40Gb/s driver IC for over-driving a 25Gb/s VCSEL using a new 2-tap pre-emphasis circuit with tunable group-delay compensation. This circuit compensates for the complex group delay of VCSELs. With this circuit, we achieve 40Gb/s low-jitter operation with 2.3dBm OMA and reduce the power consumption to as low as 312mW/ch.

A 3 Watt 39.8–44.6 Gb/s Dual-Mode SFI5.2 SerDes Chip Set in 65 nm CMOS

A Dual-mode 2 ×21.5-22.3 Gb/s DQPSK or 1 × 39.8-44.6 Gb/s NRZ to 4 × 9.95-11.2 Gb/s SFI5.2-compliant two-chip SerDes for a family of 40 Gb/s optical transponders has been fabricated in 65 nm 12-metal CMOS. By demultiplexing to 16 × 2.5 Gb/s internally, all logic and testability functions could be implemented in standard-cell CMOS, resulting in total power consumption of 3 W, 75 % lower than commercial BiCMOS SFI5 40 Gb/s SerDes ICs. Chip area is 4 × 4 mm, and the ICs are flip-chip mounted into a quad flat-pack package.

CW Lasing at 1.35

We report the fabrication of GaAs-based quantum-dot (QD) lasers grown by metal-organic chemical vapor deposition (MOCVD) above 1.3 m. We fabricated a laser diode with ten stacked InAs-Sb:GaAs(100) QD layers, grown by antimony-surfactant-mediated growth. Ground-state lasing was obtained under continuous-wave operation at room temperature at 1.35 mum, with a maximum ground state modal gain of 19.3 cm-1. These values are the highest values reported for MOCVD-grown GaAs-based QD laser.

\mu

This paper reviews the recent progress of quantum-dot semiconductor optical amplifiers, especially highlighting the properties of ultrawide band, high power, and low distortion, and signal regeneration at 40 Gb/s newly achieved in the 1.5 /spl mu/m band.

m From Ten InAs–Sb : GaAs Quantum-Dot Layers Grown by Metal–Organic Chemical Vapor Deposition

We developed a 25-Gb/s transmitter with an over-drive of 10-Gb/s VCSEL using our asymmetric pre-emphasis design. Owing to the narrow spectral width characteristics of our transmitter, we demonstrate 25-Gb/s transmission over 250-m of multimode fiber.

Quantum dots for semiconductor optical amplifiers

We report effective all-optical multicast wavelength conversion exploiting cross gain modulation (XGM) in a QD-SOA. 80 Gb/s multi-conversion on four 400 GHz spaced wavelengths is demonstrated with moderate Q2 factor penalty.

25-Gb/s transmission over 250-m MMF using over-drive of 10-Gb/s VCSEL by utilizing asymmetric pre-emphasis

A 1.55-mum polarization-insensitive quantum dot semiconductor optical amplifier was realized for the first time by applying columnar dots surrounded by tensile-strained side-barriers. The polarization dependent gain was only 0.4 dB at 1.55 mum.