||AntiResonant Reflecting Optical Waveguide (ARROW) has attracted much attention in the semiconductor optical waveguide research in recent years. Unlike conventional waveguides, waveguide in ARROW is based on the principle of Fabry-Perot Resonator as well as total internal reflection to confine light inside the core. Mode filtering can then be obtained. Therefore, ARROW becomes a large-core single-mode waveguide effectively. In this thesis, a new type of lateral ARROW-Multi-Trench ARROW is proposed. It possesses the advantages of traditional ARROW but with much simpler fabrication process. The fundamental mode is confined inside the core by means of antiresonance according to the principle of ARROW. In order to study the properties of the Multi-Trench ARROW, Effective Index Method and Transfer Matrix Method are used. We found that an asymmetric arrangement of the resonators have much better performance than symmetric one. On the other hand, a good performance in single-mode transmission was also achieved (loss of TEo = 0.5dB/cm, loss discrimination=83dB/cm with a lateral core width=lOμm) with Multi-Trench ARROW at 1.3μm communication wavelength.