OPTISYSTEM

User’s Guide -5

Amplitude Modulation

Amplitude Modulation

1) Place and connect two sine generators, CW laser, Combiner 2*1, photodiode and Amplitude modulator as

shown in figure below.

Connect Oscilloscope visualizer and RF Spectrum Analyzer to Electrical output ports – Sine generator 1,

Combiner and photodetector.

Connect Optical Time Domain visualizer and Optical Spectrum Analyzer to Optical output ports – CW Laser

and Amplitude Modulator.

Frequency of first sine generator: 2000 MHz

Frequency of second sine generator: 1000 MHz

Frequency of CW Laser: 30 THz

Power of CW Laser: 8.6 dBm

Amplitude Modulator can be found in the Default/Transmitters Library/Modulators/Optical/ folder.

2) Double click anywhere in the main layout and set the Parameters as shown in the figure below:

Bit Rate: 2.5e+009

Sequence Length: 1024 Bits

Samples per bit: 32

Run the simulation.

Results for Sine generator with 2000 MHz frequency (Modulating Signal)

X-axis limit = 0 to 4 ns

X-axis limit = 1.9 GHz to 2.1 GHz

Results for CW Laser

X-axis limit = 0 to 400ns

X-axis limit = 29.997 THz to 30.003 THz

Results for Combiner 2*1

X-axis limit = 0 to 4 ns

X-axis limit = 0 to 5 GHz

Results for Modulated signal

X-axis limit = 0 to 4 ns

X-axis limit = 29.997 THz to 30.003 THz

Results for demodulated signal

X-axis limit = 0 to 4 ns

X-axis limit = 0 GHz to 5 GHz

3) Add a optical fiber to the above setup. Remove the Combiner and 1 GHz sine wave from the system.

Change the frequency of the CW Laser to 1300 nm.

Set the reference wavelength of the optical fiber to 1300 nm.

Vary the length of the optical fiber and check if you are getting back the 2 GHz sine wave in the

Oscilloscope Visualizer and RF Spectrum Analyzer connected at the photodetector.