Driving device and method

A driving method, comprising:

• generating a driving signal to activate a light emitter such that the light emitter operates in a working range and generates an optical signal;
• detecting the output power of the optical signal to generate a corresponding electrical signal;
• adjusting the driving signal according to the corresponding electrical signal such that the output power of the optical signal approaches a preset value;
• and
• utilizing an alternating current (AC) path to receive at least one AC modulated signal such that at least one modulated optical signal is generated by the light emitter, wherein the AC path is coupled between the light emitter and an external signal source, wherein a plurality of AC modulated signals having different frequencies respectively are received by the AC path such that a plurality of modulated optical signals are generated by the light emitter,
• wherein the AC path is composed of a first capacitor, a second capacitor, a first inductor and a first resistor,
• wherein the first capacitor comprises a first terminal coupled to the light emitter and a second terminal, the second capacitor comprises a first terminal coupled to the light emitter and a second terminal, the first inductor comprises a first terminal coupled to the second terminal of the first capacitor and a second terminal receiving a first AC modulated signal and the first resistor comprises a first terminal coupled to the second terminal of the second capacitor and a second terminal receiving a second AC modulated signal.

A driving device for driving a laser diode, comprising:

• a light emitter generating an optical signal;
• a biasing circuit coupled to the light emitter for generating a driving signal such that the light emitter is activated by the driving signal and operates in a working range;
• a light receiver detecting the output power of the optical signal for generating a corresponding electrical signal;
• and
• an automatic control system coupled between the light receiver and the biasing circuit, wherein the automatic control system adjusts a current passing through the light emitter according to the corresponding electrical signal and comprises:
• a voltage divider modulating a biasing voltage of the light emitter according to a first control signal;
• an integral loop coupled to an output terminal of the voltage divider;
• and
• an alternating current (AC) path coupled between the light emitter and an external signal source, wherein the AC path receives a first AC modulated signal and a second AC modulated signal such that the light emitter emits the optical signal according to at least one frequency,
• wherein the AC path comprises:
• a first capacitor comprising a first terminal coupled to the light emitter and a second terminal;
• a second capacitor comprising a first terminal coupled to the light emitter and a second terminal;
• a first inductor comprising a first terminal coupled to the second terminal of the first capacitor and a second terminal receiving a first AC modulated signal;
• and
• a first resistor comprising a first terminal coupled to the second terminal of the second capacitor and a second terminal receiving a second AC modulated signal.