English
Menu

Silicon photonics

Which correctly describes the extinction ratio, a measure of optical transmit signal quality?

  1. AThe ratio of the optical power when sending a "1" to the optical power when sending a "0"
  2. BThe ratio of the optical power emitted by the laser to the portion of it coupled into the fiber
  3. CThe ratio of the transmitted optical power to the optical power reaching the receiver through the link
Show answer and explanation

Answer: A. The ratio of the optical power when sending a "1" to the optical power when sending a "0"

Intensity modulation makes "1" bright and "0" dark, but in a real modulator the light does not go completely off even for "0". The extinction ratio is the ratio of the "1" power P1 to the "0" power P0, expressed in dB as 10 log(P1/P0). For example, with an extinction ratio of 6 dB, P0 is about one-quarter of P1. A small extinction ratio narrows the difference between "1" and "0", making decision errors at the receiver more likely. In a Mach-Zehnder modulator, increasing the drive voltage swing raises the extinction ratio but increases the driver circuit's power consumption. The ratio of transmitted to received power represents the link loss.

Practice this topic Back to topic

Books on Silicon photonics Ad

As an Amazon Associate I earn from qualifying purchases.

More Silicon photonics questions

  1. For high-speed links of a few m or more, such as those spanning racks, what is the main reason optical fiber has an advantage over copper cables and board traces?
  2. Which is a correct advantage of pluggable optical transceivers inserted into a switch's front panel?
  3. Which is a correct challenge of CPO (Co-Packaged Optics), which mounts the optical transmit/receive components in the same package as the switch IC?
  4. In CPO, an external laser source—placing the laser outside the switch IC package and supplying only light via fiber—is often considered. What is the main reason?
  5. Which correctly describes the concept of "linear drive" (called linear pluggable optics, LPO, etc.) in optical transceivers?