Vertical-Cavity Surface-Emitting Lasers (VCSELs) are key components enabling power- and cost-efficient, high-density, ultra-high bandwidth parallel optical interconnects for data center and high-performance computing applications. This paper presents recent developments at TE Connectivity (TE) in the area of 25 Gb/s per channel-class VCSEL and optical transmitter technology for applications such as 100G and 400G Ethernet and Enhanced Data Rate InfiniBand pluggable and mid-board connectivity solutions.
Multiple streams of high definition television (HDTV) and improved home-working infrastructure are currently driving
forces for potential fiber to the home (FTTH) customers . There is an interest to reduce the cost and physical size of
the FTTH equipment. The current fabrication methods have reached a cost minimum. We have addressed the costchallenge
by developing 1310/(1490)/1550nm bidirectional diplexers, by monolithic seamless integration of lasers,
photodiodes and wavelength division multiplexing (WDM) couplers into one single InP-based device. A 250nm wide
optical gain profile covers the spectrum from 1310 to 1550nm and is the principal building block. The device fabrication
is basically based on the established configuration of using split-contacts on continuos waveguides. Optical and electrical
cross-talks are further addressed by using a Y-configuration to physically separate the components from each other and
avoid inline configurations such as when the incoming signal travels through the laser component or vice versa. By the
eliminated butt-joint interfaces which can reflect light between components or be a current leakage path and by leaving
optically absorbing (unpumped active) material to surround the components to absorb spontaneous emission and nonintentional
reflections the devices are optically and electrically isolated from each other. Ridge waveguides (RWG) form
the waveguides and which also maintain the absorbing material between them. The WDM functionality is designed for a
large optical bandwidth complying with the wide spectral range in FTTH applications and also reducing the polarization
dependence of the WDM-coupler. Lasing is achieved by forming facet-free, λ/4-shifted, DFB (distributed feedback
laser) lasers emitting directly into the waveguide. The photodiodes are waveguide photo-diodes (WGPD). Our seamless
technology is also able to array the single channel diplexers to 4 to 12 channel diplexer arrays with 250μm fiber port
waveguide spacing to comply with fiber optic ribbons. This is an important feature in central office applications were
small physical space is important.
The Detuning Loading Effect, i.e., the effects of the modulation performance on the position of the lasing mode relative
to the Bragg reflection peak, is investigated in a Modulated Grating Y-branch laser. By proper adjustment of the lasing
mode position, simultaneous chirp reduction and modulation bandwidth enhancement can be obtained. The lasing mode
position is also crucial for side mode suppression ratio and output power.
A silicon optical bench for flip chip mounted widely tunable modulated-grating Y-branch lasers is
presented. Its impact on the static and dynamic performance of the laser device is evaluated and compared with a
conventional aluminium nitride carrier. The carriers exhibited similar thermal and static performance but the
dynamic performance was limited by the electrode layout and the higher microwave losses of the silicon optical
bench. With improved microwave design of the electrodes, flip-chip mounting on a silicon optical bench is
promising for low cost assembly of high-speed multi-electrode devices.