The number of bits of information that can be obtained from a single unmodulated wavelength of light depends on the modulation scheme used and the number of distinguishable states that can be encoded.
In the case of unmodulated light, where there is no intentional variation or encoding of information, a single wavelength of light does not carry any additional information. Unmodulated light consists of a single frequency (wavelength) and does not contain any variations that can be used to encode data.
To transmit information using light, modulation schemes are employed, such as amplitude modulation (AM), frequency modulation (FM), or phase modulation (PM). These modulation techniques allow for encoding information by varying the amplitude, frequency, or phase of the light wave, respectively.
The amount of information that can be transmitted depends on the number of distinguishable states or levels that can be encoded in the modulation scheme. For example, in binary modulation schemes like binary amplitude modulation (BAM) or binary phase modulation (BPM), two distinguishable states are used, typically represented as 0 and 1. Each state represents one bit of information.
In more complex modulation schemes, such as quadrature amplitude modulation (QAM), multiple states can be encoded, allowing for the transmission of multiple bits of information per symbol. For example, 16-QAM can encode 16 different states, representing 4 bits per symbol.
In summary, without modulation, a single unmodulated wavelength of light does not carry any additional information. To encode information in light, modulation schemes are used, and the number of bits of information per wavelength depends on the chosen modulation scheme and the number of distinguishable states that can be encoded.