There has been much effort devoted to frequency conversion technology due to strong demand for optical communication
systems. A frequency converter converts an incoming optical carrier of one frequency to an outgoing
optical carrier of another frequency while preserving the quality of carried data. The all-optical approach is
promising for such a purpose because not only the complexity and power consumption of a converter are much
reduced but also the flexibility and reconfigurability are greatly improved. However, most proposed methods,
such as applying cross gain modulation in semiconductor optical amplifiers, suffer from the need of a probe or
a pump beam besides the incoming optical carrier, making systems complicated and costly. In this study, we
propose to use semiconductor lasers as frequency converters instead, where no probe or pump beam is necessary.
When a semiconductor laser is subject to an incoming optical carrier, equivalently an external optical injection,
it can enter into period-one dynamics through Hopf bifurcation. By taking advantage of the dynamics, tens of
gigahertz of frequency conversion can be achieved, which can be continuously and dynamically tuned by controlling
the injection level and frequency. The conversion efficiency and transmission efficiency can also be varied
through the change of both injection parameters. Their behaviors as functions of the parameters, however, are
opposite to each other. High conversion efficiency is observed to achieve under low levels of injection, where
strong filtering of frequency may not be necessary and significant signal amplification can be achieved. Low
bit-error-rate and a 3-dB penalty are also observed, suggesting the quality of carried data is preserved.