In this paper, the dynamic characteristics of four-wave mixing, period-one and period-two oscillations, and optical injection locking state are demonstrated for a 8-µm-radius directional-emission microdisk laser subject to optical injection. For the microdisk laser biased at 7 mA, the 3 dB bandwidth of the small signal modulation response is increased from 3.4 to 137 GHz due to the optical injection locking with an injected optical power of 0.5 mW. The rapid development of computing systems, data centers, and other short reach datacom networks has driven the demand for optical output devices with higher bandwidth. One potential candidate to meet this requirement is the directly modulated semiconductor microlaser due to its compactness and low cost However, the 3 dB modulation bandwidth is ultimately limited by its relaxation resonance frequency for a typical semiconductor laser. Optical injection-locking is an effective technique to enhance the modulation bandwidth. In this paper, dynamical characteristics are investigated for an 8-µm-radius microdisk laser connected with a 2-µm-width output waveguide subject to optical injection. Dynamic states un- der optical injection including four-wave mixing, period double and optical injection locking are observed at different detuning wavelengths, and the enhancement of the 3 dB bandwidth due to optical injection are demonstrated. Microdisk lasers are fabricated using an AlGaInAs/InP laser wafer grown by metal-organic chemical vapor deposition, with the technique process similar as in [1, 2]. The scanning electron microscope (SEM) cross-sectional-view for a cleaved waveguide which is directly connected to a microdisk resonator is shown in Fig. 1(a), while the microscopic picture of a fabricated microlaser laser is shown in Fig. 1(b). The microdisk cavity is laterally confined by BCB cladding layer, on which a pad patterned P-electrode is formed using lifting off technology. After cleaving over the output waveguide, the microdisk laser is bonded p-side up on an AlN submount and mounted on a thermoelectric cooler (TEC). The output powers coupled into a tapered multi-mode fiber (MMF) are measured as functions of the continuous-wave (CW) injection current and plotted in Fig. 2(a) together with the corresponding applied voltage. The maximum output powers obtained at 296, 290 and 288 K are 115.5, 163.3 and 176.2 µW, respectively. A series resistance of 28 Ω is estimated from the VI curve, and the threshold current is about 5.5 mA at 288 K. The laser spectra are measured by an optical spectrum analyzer (OSA) at the resolution of 0.1 nm. The spectrum measured at 288 K for the microdisk laser is plotted in Fig. 2(b) at an injection current of 10 mA, which shows single mode operation at 1540.1 nm with the side mode suppression ratio (SMSR) of 35.4 dB. The optical injection locking provides an effective and promising method for generating mi- crowave signals as well as enhancement of modulation bandwidth Setting the output power of the tunable laser to 500 µW with the wavelength detuning ∆λ = λI − λC with λI and λC injection