Fig. 1. Polarized mode and line bandwidth

Fig. 2. Mode state test device of birefringence HeNe laser

Fig. 3. Longitudinal mode spectrum of a birefringence HeNe laser

Fig. 4. // light and ⊥ light intensity tuning curve before frequency diffe-rence adjustment

Fig. 5. // light and ⊥ light intensity tuning curve after frequency diffe-rence adjustment

Fig. 6. Variation diagram of spatial burning-hole of laser longitudinal modes on Ne²⁰ gain curve during cavity length tuning