Technical Parameters

Low Freq: External current modulation input for SOA, supports frequency signals from 0 to 40 MHz, with a minimum pulse width of 10 ns.

USB: Communication interface with the computer.
AC 220V: Power supply cable.
Power: Device power switch.
Fiber Fix: Seed light input port.
Fiber Out: Modulated light output port.

Operation process

1.Connect the AC 220V power cable, connect the USB cable to the PC, and press Power to start the SOA driver.

2.Open the SOA driver program on the PC, press Connect to link the SOA driver device. When the device model appears in the top-right corner, the connection is successful. Check if the LD Actual Temp temperature matches the LD Temp Setpoint temperature, indicating that the temperature control is functioning properly. You can modify the LD Temp Setpoint temperature by pressing Set Temperature to adjust the SOA working temperature, though 25°C is typically sufficient.

 As shown below:

 3. Control the seed light input to around 1mW and insert it into Fiber Fix. Then, use an optical fiber jumper to connect Fiber Out, with the other end connected to the optical power meter. At this point, the SOA does not have any current, so the seed light will not be amplified, but a faint seed light power may still be observed on the power meter.

4. In the software interface on the PC, first, drag the Start progress bar to the minimum (81mA), then set the Limit to 500mA (current limit for the SOA). Press Set Parameters and then press Run: DC to inject a minimum current of 81mA into the SOA. The value of Start represents the current injected into the SOA. Gradually increase the value of the Start progress bar. Each time you move it, you must press Set Parameters for the change to take effect. You will observe that the optical power on the power meter gradually increases, with the optical power around 30mW at 500mA. At this point, we have achieved the optical power amplification function of the SOA.

 Spectral images of SOA before and after optical amplification.

Optical Modulation

The value of "Start" refers to the current injected into the SOA when there is no external signal input. When a voltage value (Vset) is input through the Low Freq port, the current in the SOA will be the value of "Start" plus Vset × 400. For example, if an external voltage of 1V (with a 50Ω impedance) is applied, the actual current value will be 400 × 1 + 81 = 481mA (there may be some deviation from the actual situation, so it is recommended to re-calibrate before modulation). Using this function, by inputting a modulation signal into the Low Freq port, we can perform amplitude modulation on the SOA, effectively acting as an optical switch.

 SOA modulation optical time-domain signal under a 40 MHz square wave modulation signal input