US Patent 7639954 Driver for an optical transmitter

A modulation driver for delivering an output modulation current for driving an optical source of an optical transmitter, the output modulation current comprises a first modulation current region characterised with a first temperature gradient and a second modulation current region characterised with a second temperature gradient, said first modulation current region and said second modulation region being for delivering modulation current at a first temperature range and a second temperature range, temperatures of said second temperature being higher than temperatures of said first temperature range, said second temperature gradient being larger than said first temperature gradient.