Using the bichromatic laser whose two frequency components are linearly polarized with the polarization directions orthogonal to each other (lin⊥lin), a better performance coherent population trapping (CPT) based atomic clock can be realized. A laser system is realized, which is a master-slave injection locking configuration with an external-cavity diode laser (ECDL) as the master and a microwave modulated vertical-cavity surface-emitting laser (VCSEL) as the slave by injection locking the + 1st sideband of the output multichromatic laser, and the quasibichromatic laser beam is obtained. The behaviors of the obtained beam and the effects of applying it to generate CPT resonance with atoms are experimentally studied, and some meaningful results provide helpful reference to CPT atomic clock related studies.