1.3 μm InGaAlAs/InP VCSEL for 10G Ethernet W. Hofmann 1 , M. Ortsiefer 2 , E. Rönneberg 2 , C. Neumeyr 2 , G. Böhm 1 , and M.-C. Amann 1 1) Walter Schottky Institut, Technische Universitt München, Am Coulombwall 3, 85748 Garching, Germany, [email protected] 2) VERTILAS GmbH, Lichtenbergstr. 8, D-85748 Garching, Germany, URL: www.vertilas.com Abstract: 1.3 m InGaAlAs/InP VCSELs for 10G Ethernet solutions are presented. High modulation bandwidth and error-free data transmission at 10.3 Gb/s up to 75C over 10 km of SMF is demonstrated. 1. Introduction Vertical-cavity surface-emitting lasers (VCSELs) emitting in the 1.3 m wavelength range have reached a degree of maturity allowing to enter industrial applications [1]. Smaller form-factors and lower power-dissipation standards in optical communication modules gear up the need for new generations of ultralow power long wavelength lasers. The 10GBASE-LR (long range) standard, to be found in the IEEE 802.3ae recommendation, describes 10G Ethernet at 1.3 m over a link of 10 km of the widely deployed standard single mode fiber (SMF). For the 10GBASE-SR (short range) standard, 850 nm VCSELs are already used as cost-effective light sources. Recently, many efforts have been made to improve VCSEL performance at 1.3 m wavelength including wafer-fused devices [2] and nitrogen con- taining quantum wells [3]. Our solution is a InP-based, monolithic approach, using a buried tunnel junction (BTJ) as current aperture as described in [4]. With this concept, we have demonstrated devices at 1.55 m with superior high-speed performance [4]. Furthermore, we mounted our device into a transmitter optical sub-assembly (TOSA) module which can easily be integrated in existing transmitter infrastructure. 2. Structure and VCSEL Characteristics The basic structure of the present high-speed 1.3 m VCSEL is basically the same as described previously [4] with optimized heat management in the cladding layers and improved bottom-mirror reflectivity. The epitaxial output mirror is made of InGaAlAs/InAlAs layer pairs and the active region consists of 7 strained quantum wells separated by tensile strained barriers. The hybrid back mirror of these lasers is made of 3.5 pairs of CaF 2 /ZnS and a gold layer. Laser chip and schematic structure is shown in Fig. 1. BCB is used as low-dielectric constant passivation to enable high-speed operation. For compatibility with commercial transceiver modules, the chip was mounted into a TOSA module which is also shown as inset in Fig. 1. . Fig. 1. Schematic of the 1.3 m VCSEL; laser chip and TOSA as inset. Fig. 2. L-I-V characteristics Fig. 3. Optical spectrum The device presented here exhibits a single-mode output power exceeding 3 mW at room temperature and around 0.6 mW at 80C as shown in Fig. 2. The fiber-coupling efficiency of the TOSA module is typically around 50%. The threshold current remains constant at 2.7 mA for 20C and 80C, as these devices for optical communications are optimized for high-temperature performance. The differential series resistance is around 30 Ω and well matched to the transmission lines of the driver modules. A single-mode spectrum at 1.33 m is presented in Fig. 3. The side- mode suppression ratio was found to be at least 40 dB over the relevant current and temperature range. 11 MB3 14.00–14.15 978-1-4244-1783-4/08/$25.00©2008 IEEE