| dc.description.abstract | Frequency in the range of microwaves can be used for various purposes RADAR
components such as ground penetrating, radio on fiber systems etc. so that
tunability and power frequency source is a very important thing. Tunable
microwaves frequency has been able to be generated by utilizing beat signal of
mixing of two DFB (distributed feedback) laser diode with optical heterodyne
technique. The observation result showed that tunneling one of the laser
temperature cause generated microwaves signal able to be tuned. DFB 2 laser set
in fix current and temperature, whereas temperature of DFB 1 laser is tuned until
its wavelength close to DFB 2 laser wavelength. Maximum frequency of
microwaves detected is 8,432 GHz due to limitations range of reading RF
Spectrum Analyzer. As the result, the rate of the average change of microwaves
frequency is 791 MHz for each temperature change of 1℃. Characterisation of
optical power and laser wavelength versus its influent parameters i.e. temperature
and laser injection current has been done as initial testing. Generated
microwaves frequency able to be optimized by optical amplifier which has ability
to gain input signal of optical power from laser diode. The more current produce
more optical power laser. Minimum value of the optical power is 0,06 mW of 10,8
mA current and Signal to Noise Ratio (SNR) value 45,51 dB and maximum value
is 0,9 mW of 20 mA current and SNR value 56,55 dB. Whereas by addition of
optical amplifier, the power of optical laser increase significantly with minimum
value 13,5 mW of 10,8 mA current and SNR value 51,59 dB. The larger the SNR
value is the better, this result means showed that the SNR will always be degraded
as the signal passes through any microwave component, it is mean that this gain
is amplify the noise too. | en_US |
