Record 5200km reach at 40G


In a post-deadline paper at September's European Conference on Optical Communications in Copenhagen,

Dr Christian Rasmussen of Mintera Corp said the company had demonstrated error-free transmission of 40 channels at 42.7Gbit/s over a "record" distance of 5200km on UltraWave fibre without electrical regeneration. Mintera was founded in October 2000 and develops 40Gbit/s transport systems for metro-core, regional, long-haul and ultra-long-haul networks.

The net gain variation for four spans was 1.7dB (0.4dB/span), channel power variation after 5200km was 4.5dB, back-to-back sensitivity gave an OSNR of 15dB at a bit-error rate of 10-12 and 18.5dB after 5200km(Fig.1).

Mintera says this was achieved with typical terrestrial optical amplifier spacing of 100km, channel spacing of 100GHz, and by using all-Raman amplification (see Fig.2, right).

The results represent "a new proof point that 40Gbit/s ultra-long-haul optical transport is being commercialised," says president and CEO Menachem Abraham, approaching trans-Atlantic distances even with 100km spans and turnkey terminal equipment.

The multi-service transmitter and receiver in Mintera's system employ electronic time division multiplexing for interfacing to the lower-speed client signals (e.g. multiple 10Gbit/s bit streams from Ethernet switches, routers, SONET add-drop multiplexers, optical switches), enhanced forward error correction (EFEC) technology, and Mintera's chirped carrier suppressed return-to-zero (CCS-RZ) modulation on the ultra-long-haul optical link.

Mintera says its flexible multi-service 40Gbit/s product-set allows upgrade of existing infrastructure to 40Gbit/s while decreasing initial deployment capital expenses and lifetime operational costs.

Kamelian and u2t have combined their SOA and PIN photodiode powers to demonstrate a 40Gbit/s receiver with sensitivity better than –17dBm.

An experimental collaboration has combined Berlin-based u2t Photonics AG's ultra-fast PIN photodiode (PD) with Glasgow-based Kamelian Ltd's high-gain, low-noise-figure semiconductor optical amplifier (SOA). Together they have demonstrated a 40Gbit/s receiver with better than –17dBm sensitivity (at a bit error rate of BER=10-9).

The combination takes advantage of the performance of Kamelian low-noise SOAs in tandem with u2t's waveguide integrated photodiode to produce a receiver that is highly sensitive, has a wide dynamic range and is robust to high input signal strength (Pmax >10dBm).

For particular applications, the approach circumvents the need for an integrated transimpedance amplifier (TIA), the pre-amplified PIN provides a rugged, high-sensitivity solution to the demands of 40Gbit/s transmission.

The performance of the SOA/PIN is follows:

  • Responsivity better than –17dBm (10-31 BER, 231-1 PRBS);
  • Dynamic range > 15dB;
  • Receiver operation > 50GHz;
  • No requirement for optical isolator between the SOA and PD.

"This is an excellent initial result that will give our customers additional flexibility as they consider design options for 40Gbit/s systems," says Paul May, Kamelian's CEO.

"Both Kamelian and u2t are committed to continued collaboration towards a fully integrated co-packaged SOA/PIN receiver to address the 40Gbit/s market," said Guenter Unterboersch, COO and founder of u2t.

The components used for the demonstration are commercially available from both companies (Kamelian's product is the OPA 20-C; u2t's the XPDV 2020R).

u2t photonics was spun out of the Heinrich Hertz Institute in Berlin, in 1998 and makes photodetectors, optical receiver products, pulse sources, modulators and multiplexer accessories. With its experience in indium phosphide, u2t is developing, producing and marketing receivers addressing the requirements of both test and measurement systems up to 65GHz and SONET/SDH-compliant OC-768 receiver components for a variety of reaches.

Kamelian, Glasgow and Oxford, UK, designs and makes both discrete SOA devices and more complex SOA-based integrated products for optical networks.

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