When using the supplied laser driver for modulating the laser diode current, the 3-dB modulation bandwidth is 6 MHz. This bandwidth limit is imposed by the driver. In principle, the diode current can be modulated up to GHz frequencies with custom drivers. The modulation amplitude is physically limited by the laser cavity FSR, which is typically about 4 GHz. To avoid mode hops during modulation, we recommended limiting the modulation signal for a slightly smaller modulation range.