Page 66 - rise 2017

70 10
Repitition Rate 9
65
8 7
Pulsewidth
Repitition Rate (Khz) 55 6 5 4 Pulsewidth (µs)
60
50
45
2 3
40
1
35 0
35 45 55 65 75 85 95
Pump Power (mW)

Figure 4: Pulse widths and repetition rates versus incident pump powers

Figure 5 shows the relationship between the average output power and pulse energy with pump power
in the proposed Q-switched EDFL. It is observed that both the average power and pulse energy
increases with the increment of pump power. The average output power can be linearly increased
from 1.3µW – 3.34µW by tuning the pump power from 39 to 96 mW. The maximum pulse energy of
0.054 nJ was obtained at pump power of 96 mW. The increment of pump power leads to a raise of
average output power and shorten the pulse width and hence higher pulse energy is extracted in the Q-
switching process. To investigate the stability of our Q-switched pulse, the radio-frequency (RF)
spectrum is obtained at the pump power of 96 mW as shown in Figure 6. The RF spectrum shows the
fundamental frequency of 61.77 kHz with a high signal to noise ratio (SNR) of 59.89 dB. The SNR
indicates good pulse train stability, comparable to Q-switched fiber lasers based on CNT and
graphene [6-8].

4 0.06
3.5
0.05
3
Output Power (µW) 2.5 2 0.03 Pulse Energy (nJ)
0.04

1.5

1 Output Power 0.02
Pulse Energy
0.01
0.5
0 0
30 40 50 60 70 80 90
Pump Power (mW)

Figure 5: Average output powers and pulse energies versus incident pump powers