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Sagnac speed meter (SSM) topology is known as an alternative technique toreduce quantum back-action in gravitational-wave interferometers. However, anypotential imbalance of the main beamsplitter was shown to reduce the quantumnoise superiority of speed meter at low frequencies, caused due to increasedlaser noise coupling to the detection port. In this paper, we show thatimplementing balanced homodyne readout scheme and for a particular choice ofthe local oscillator (LO) delivery port, the excess laser noise contribution toquantum noise limited sensitivity (QNLS) is partly compensated and the speedmeter sensitivity can outperform state-of-the-art position meters. This can beachieved by picking the local oscillator from interferometer reflection(\textit{co-moving} LO) or the main beamsplitter anti-reflective coatingsurface (BSAR LO). We also show that this relaxes the relative intensity noise(RIN) requirement of the input laser. For example, for a beam splitterimbalance of $0.1 \%$ in Glasgow speed meter proof of concept experiment, theRIN requirement at frequency of 100Hz decreases from $4\times10^{-10}/\sqrt{\rm Hz}$ to $4\times 10^{-7}/\sqrt{\rm Hz}$, moving the RINrequirement from a not practical achievable value to one which is routinelyachieved with moderate effort.

Quantum noise cancellation in asymmetric speed meters with balanced homodyne readout