True bidirectional optical interconnects over multimode fiber

Abstract

We report the fabrication and properties of 850 nm wavelength AlGaAs/GaAs-based transceiver chips, in which vertical-cavity surface-emitting lasers (VCSELs) and photodiodes are monolithically integrated. Various types of devices allow half-and full-duplex bidirectional optical interconnection at multiple Gbit/s data rates over a single butt-coupled glass or polymer-clad silica optical fiber with core diameters of 100 or 200 µm. Whereas metal-semiconductor-metal (MSM) photodiodes are employed for these large-area fibers, we also investigate the integration of PIN-type photodiodes which appear more promising in combination with standard 62.5 or 50 µm core diameter graded-index multimode fibers. This interconnect solution based on two identical chips is attractive owing to lower volume, weight, and cost. Applications will be found in home, in-building, industrial, or automotive networks and potentially within computer clusters or central offices.

VCSELs: A Research Review

“…The use of these lasers (instead of red emitting LEDs) in combination with 200 µm core diameter polymer-clad silica (PCS) fibers in data buses was strongly promoted by the car manufacturer Daimler [66] (see also [22] for a bidirectional transmission solution using this medium). Suitable high-temperature-compatible VCSELs had been developed for that purpose.…”

“…• Bidirectional single-wavelength (no WDM) Gbit/s-rate data transmission over multimode fiber [22][23][24] (see also the end of Chap. 2 of this book) can lead to cost-effective transceiver solutions for some application areas and thus might be considered for commercialization.…”

VCSELs with monolithically integrated photodiodes for single-fiber bidirectional data transmission in the Gbit/s range

“…The reflection coefficient could be reduced to a value of 1.3% for the wavelength region around 850 nm [5]. For devices with 1000 nm thick absorption region in the PIN PD and the aforementioned layer structure, the responsivities are measured to be 0.56 A/W for the PDs with included VCSEL and 0.45 A/W for separately grown solitary PDs (see Fig.…”

“…Using the complete transceiver device, the VCSEL as transmitter and the PD as receiver, simultaneous (full-duplex) data transmission over one single fiber was achieved with data rates of 2.5 Gbit/s [5]. In this experiment, a 50 m-long graded-index multimode fiber with a core diameter of 100 mm was used.…”

VCSEL Fundamentals

“…As an example, data rates of 2.5 Gbit/s were transmitted over 50 m of a 100 µm core diameter graded-index MMF in full-duplex mode [157]. More recently, halfduplex transmission of 9 Gbit/s in back-to-back mode and of 7 Gbit/s over a 500 m long 50 µm core diameter fiber was shown, both with a VCSEL-PIN photodiode [157] chip [158]. Full-duplex operation could be demonstrated up to 8 Gbit/s back-to-back and 6 Gbit/s over 500 m of OM3 fiber [159].…”