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20 February 2008


Mitsubishi launches first 40Gb/s EAM-LD with built-in driver

At next week’s Optical Fiber Communication conference & exposition (OFC 2008) in San Diego, CA, USA, Tokyo-based Mitsubishi Electric Corp is launching what it claims is the world’s first electro-absorption modulator laser diode (EAM-LD) with a built-in driver IC for 40Gb/s optical transmission, as well as a photodiode (PD) with a built-in pre-amplifier IC (also for 40Gb/s).

With Internet traffic increasing, service providers are rushing to expand optical communication network transmission volume, says Mitsubishi Electric. To fulfill the demand for the upgrade of 10Gb/s networks to 40Gb/s (enabling faster optical transmission between metropolitan area networks and routers), transmission equipment manufacturers are looking for a small and low-priced optical transceiver that can also be mounted with high-density inside their equipment.

The LDs, EAMs and their drivers within the optical output stage of transceivers had already been integrated into one package for 10Gb/s applications, but not for 40Gb/s. Optical transceivers for 40Gb/s previously installed two modules: the discrete EAM-LD and the driver IC. Transceivers also need improvement in efficiency when converting optical power to/from electrical current, says Mitsubishi Electric.

The new FU-642SEA 40Gb/s EAM-LD incorporates a laser diode and a monolithically integrated EAM together with a built-in driver IC in the same package. By integrating the discrete transmitter and the driver IC, the module realizes stable transmission, while helping to make transceivers smaller with fewer components. Mitsubishi Electric says that eliminating the use of coaxial cables for high-frequency connection also improves the optical waveform, as well as saving adjustment time during production and reducing other costs.

Also, in addition to a built-in pre-amplifier IC, the new FU-342SPP photodiode has a newly developed optical waveguide shaped detection area. This leads to an efficiency (sensitivity) of 0.9Amps/Watt for converting optical power to electrical current (up 50% on previous models of 40Gb/s PD). High sensitivity helps to realize stable transmission.

The devices will make transceivers smaller and lower-priced, and contribute to more stable optical transmission at 40Gb/s, says Mitsubishi Electric.

Sample shipment will begin in April (costing ¥700,000 for the FU-642SEA and ¥550,000 for the FU-342SPP).

SFP+ compliant driver IC for 10Gb/s DMLs

Mitsubishi Electric is also launching the ML01720A driver IC for 10Gb/s direct modulation laser (DML) diodes. The new IC is small enough (4mm x 4mm) for installation in optical transmission devices compliant to the enhanced 8.5 and 10Gb/s small-form-factor pluggable module (SFP+) standard.

While network equipment for fiber-optic communication widely uses 10Gb/s optical transceivers compliant to the 10Gb/s small-form-factor pluggable module 2 (XFP) standard, carriers have been looking for transceivers that are small and operate at low power consumption with a wide temperature range, enabling high-density installation, says Mitsubishi Electric. The SFP+ standard that is being considered uses smaller transceivers with lower power consumption.

For transmitter optical sub assemblies (TOSAs) and their driver ICs used in SFP+ compliant transceivers, there is strong demand to reduce the power consumption and the space required for mounting on printed circuit boards (PCBs). Following the earlier development of the TOSA for SFP+, Mitsubishi Electric has now developed a SFP+ compliant driver IC for 10Gb/s direct modulation LDs in a package that measues just 4mm x 4mm. The firm claims that this is the smallest in the industry with a single chip combining a driver core, an automatic laser power control loop (APC) and a function that shuts down automatically to reduce standby power consumption. This reduces mounting space on PCBs to 47% compared to Mitsubishi Electric’s previous model (ML01618).

Also, compared to the ML01618, power consumption has been reduced by 55% through using microwave design techniques. When used with Mitsubishi Electric’s FU-456RDF-6M1 TOSA for SFP+, total power consumption of the optical transmitter block can be reduced to 410mW, just two-thirds of the maximum limit of 600mW for SFP+.

In addition, due to the low performance of LDs at high temperature, the rise and fall of the optical output waveform largely limit the transmission speed. To avoid this, an optical output waveform adjusting function enables operation at 85ºC (10ºC higher than the ML01618).

Sample shipment will begin in March (costing ¥9000), with production targeted at 20,000 parts per month.

See related items:

First hot-swappable 10Gb/s tunable transceiver for DWDM

Mitsubishi sampling 10Gbps XFP module with power consumption cut to 2.5W

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