PT Journal
AU Baryshev A.
   Hovenier J.N.
   Adam A.J.L.
   Kašalynas I.
   Gao J.R.
   Klaassen T.O.
   Williams B.S.
   Kumar S.
   Hu Q.
   Reno J.L.
TI Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser
SO Physics Letters
PY 2006
VL 89
AB We have studied the phase locking and spectral linewidth of an ~ 2.7 THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8 GHz is compared with a microwave eference by applying conventional phase lock loop circuitry with feedback to the laser bias current. Phase locking has been demonstrated, resulting in a narrow beat linewidth of less than 10 Hz. Under requency stabilization we find that the terahertz line profile is essentially Lorentzian with a minimum linewidth of ~ 6.3 kHz. Power dependent measurements suggest that this linewidth does not approach the Schawlow-Townes limit.
ER