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In this study, we propose a polarization-separated external cavity feedback structure based on a volume Bragg grating (VBG) that folds the optical path of a free-running diode laser into a non-straight direction for linewidth narrowing and central wavelength locking. By employing diode laser polarization splitting technology and external cavity feedback technology, a similar output power and narrow linewidth but a smaller current drift coefficient of central wavelength are demonstrated by comparing with the standard straight external cavity feedback structure. Experimental results show that the current drift coefficient of central wavelength reduce to 1/5 that of the traditional method. According to our research, this is the first report on folding the extended external cavity feedback optical path in a non-straight direction basing on polarization splitting technology, providing a new method for external cavity feedback based on the VBG. • A polarization-separated external cavity feedback structure based on a VBG for linewidth narrowing and central wavelength locking is proposed. • A similar output power and narrow linewidth but a smaller current drift coefficient of central wavelength are demonstrated. • The locked central wavelength as a function of operating current shifts at a rate of approximately 2.625 pm/A. [ABSTRACT FROM AUTHOR]