# Laser diode bitrate datasheet

I'm a student studying communications engineering. I'm trying to understand why this particular laser diode is made for 155 Mbps and 622 Mbps. I'm thinking that the bitrate is entirely dependent upon the bandwidth of the photodiode. I can see from the datasheet that $f_c = 2 \text{ GHz}$ and so what I'm thinking is that you could have, a 1 GHz carrier with around 2 GHz of data. So wouldn't this allow for a 2 Gbps bitrate? I'm just wondering if this thinking is correct.

The datasheet can be found here: Datasheet

• Well, apart from the theoretical signal processing concepts, physical devices are made to be used in real, physical systems. 155 Mbps and 622 Mbps are common data rates used on fiber-optic SONET networks, specifically OC-3 and OC-12 lines. – Jason R May 19 '13 at 12:40
• Yeah, that makes sense, but also, is my logic correct? You could actually run it at a higher speed? – user968243 May 19 '13 at 14:24
• Yes, in theory you could. Note that for carrier-modulated systems, you would need to ensure that the carrier is high enough to accommodate the bandwidth of the modulated signal (i.e. a 1 GHz carrier can't have any larger than 1 GHz one-sided bandwidth). – Jason R May 19 '13 at 15:10