Datasheet

Chapter 4: QCL Operation
4.3.4. Bandwidth of multi-mode FP QCLs
In the case of FP QCLs, the bandwidth is defined as the wavelength range in which
99% of the power is emitted. It depends on the driving current and is not affected by
the operating temperature. ALPES LASERS QCLs operated in CW mode can withstand
any pulse length.
4.4. I-V curve and emitted power
Figures 4.4 show the IV curves of DFB and FP lasers operated in CW at different
temperatures. On the same graph the emitted power is plotted as a function of op-
eration current, showing the current threshold for each temperature. For example,
the DFB laser operated in CW mode (figure 4.4 ) has a threshold of 0.6 A at 20
◦
C. It
can be seen that cooling the QCL during operation enhances its performance as the
threshold current decreases and output power increases.
CAUTION:
Do not operate the laser with a temperature and current above the
values specified in the ALPES LASERS datasheet. Permanent
damage may result.
Figure 4.5 can be used to illustrate the temperature and current tuning of a DFB
QCL operated in pulsed mode:
• the power increases from 3 to 6 mW using a peak current of 4 A and varying
the temperature from -30 to 30
◦
C.
• for a temperature of 0
◦
C, the power increases from 0 to 5.5 mW by increasing
the peak current from 2 to 5 A.
48 QCL user’s manual v3.0