An integrated optical chip for fiber optical gyroscope(FOG) is designed and fabricated on GaAs.To achieve a high modulation efficiency and a small chip size,a deeply etched waveguide structure is employed,and accordingly a multimode interference(MMI) coupler is used as the 1 × 2 power splitter.The size of the chip is about 8.5 mm × 0.5 mm,which is much smaller than that of LiNbO3-based chips.The experimental results show that the extinction ratio(ER) of the TE mode to the TM mode is over 26 dB and the value of Vπ·L of the phase modulators is 18 V·cm.The method to further lower Vπ is discussed.
