en تخصصي Special كاربردي Applicable <font face="times new roman,times,serif" size="2">In this research, tunability of a commercial diode laser has extended to about more than ± 11 nm using a V-shaped external-cavity fabricated around the laser. Although under normal condition it can be tuned up to about ± 4 nm just by changing its temperature and injection current. Such modified diode laser has then used in a difference-frequency generation (DFG) experimental setup as pump source in order to continuous tuning of the generated DFG spectrum up to about ± 100 nm from 4.76 m to 4.85 m in the mid-infrared region. An AgGaS2 crystal is used as nonlinear medium.</font> V-shaped External Cavity, Difference-Frequency Generation (DFG) laser, CO spectroscopy. 41 45 http://ijop.ir/browse.php?a_code=A-10-326-1&slc_lang=en&sid=1 Alireza Khorsandi A.khorsandi@phys.ui.ac.ir 10031947532846001007 10031947532846001007 No Department of Physics, University of Isfahan Maryam Maleki maryam_m4902@yahoo.com 10031947532846001008 10031947532846001008 Yes Department of Physics, University of Isfahan