DFB Laser in Compact TO-CAN Package

Abstract

We developed a compact TO-CAN module with a 1.3-�m InGaAlAs directly-modulated laser. We achieved a record relaxation oscillation frequency slope value of 4. 85 GH7JrnA 1/2 and a 40-Gbps modulated transmission over a 40-km-long single-mode fiber. oelS codes: (140.5%0) Scmiconductor laser; (230.3120) Integrated optics dcvic�"S 1_ Introduction The recent rapid increase in data and Internet traffic means that we must increase the speed of optical network systems from 10 to 40 Gbps. In datacenters, there is an increasing demand for the processing of 40-Gbps optical signals. This application has conventionally employed an electroabsorption modulator integrated with a distributed feedback (DFB) laser (EML) in a but terfly package with expensive coaxial connectors. The demand that the size and cost of such a 40-Gbps light source be reduced has been increasing, and the standardi7. ation of 40-Gbps Ethernet (40GbE) has been discussed. Although a multi-lane interface was adopted in this standardization [11, a compact serial-interface remains attractive because it can provide great reductions in size, cost and power consumption. Directly modulated DFB lasers (DML) are widely used at a data rate of 10 Gbps because they are more compact and consume less power than EMLs. Recently, there have been several studies on the 40-Gbps operation of 1.3-�m DML chips [2-4]. These studies report a high relaxation oscillation frequency (fr) for DML chips. However, considering the demand for a 40-Gbps light source, there is a strong need for both a DML chip and a compact and low-cost package whose RF signal interface can be connected to printed circuits board (PCB) without expensive connectors or coaxial cable. The development of a DML in a compact transistor outline (TO)-CAN module with a low-cost flexible printed circuit (FPC) connection that can be operated at 40 Gbps would be very attractive. There are two difficulties regarding the 4O-Gbps operation of a DML chip in a TO-CAN package with an FPC connection. One is that it increases the fr of the DML chip. The other is finding a way to obtain a sufficient