OCTOBER 17, 2006 -- Mitsubishi Electric Corporation (search Mitsubishi Electric) has completed development of the ML9xx46 series, a high output laser diode capable of transmission rates of 2.5 Gbits/sec. The diode will be most suitable for applications such as fiber-to-the-home (FTTH)-based GPON (search GPON) networks. Sample shipments will begin on November 11, 2006.
FTTH, most widely implemented as passive optical networks (PON), will need to improve its downstream transmission speed (from access station to subscriber) to respond to increasing needs, say Mitsubishi Electric representatives. PON transmission rates are below 1.25 Gbits/sec, and many access stations are moving towards the improved GPON transmission rates of 2.5 Gbits/sec. GPON will begin serious commercialization in the U.S. starting in Japanese fiscal 2007.
With improvements in transmission speed, the industry has sought to secure optical input/output strength on the receive side by using higher than previous optical output on the transmitting side. According to company representatives, the ML9xx46 series can respond to increasing speed demands with one of the best optical output rates in the industry, as well as a large operating range of -40 ° C to +85 ° C.
The ML9xx46 series also features:
• High optical output for high-speed FTTH.
Laser diodes have been limited to an optical output of 10 mW because response speed diminishes with optical output at high temperatures. By optimizing the construction of the active layer where the laser diode emits light, the ML9xx46 series features improved optical conversion efficiency at high temperatures with an optical output of 15 mW, say company representatives. Mitsubishi Electric says it has also improved modulation bandwidth by reducing capacitance of the laser diode. A 15-mW optical output with a response time of 2.5 Gbits/sec will increase speeds of FTTH.
• Reduced power consumption of transmitter using high coupling efficiency lens.
Using an aspherical lens increases coupling efficiency (efficiency of the light entering the fiber from the laser) to 70% in the ML920T46S model. This reduces operating current, which leads to reduced power consumption in the transmitter.
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