The minimum RF power required for injection locking of the light pulsations in the output of a CW room-temperature AlGaAs double-heterostructure (DH) junction laser was found to depend exponentially on ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f-f_{r}</tex> ), where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</tex> is the RF injection frequency and f <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> is the self-pulsing frequency, and also, to depend inversely on the self-pulsing strength of the laser. Nearly 100-percent modulation depth is achievable at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f=f_{r}</tex> , and slight reduction of modulation depth occurs when <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f \gg f_{r}</tex> .