In this paper, we propose an approach for implementing quantum-enhanced stimulated Raman scattering (QESRS) microscopy using a dual-polarization scheme. This approach has advantages for high-power operation and enables ultrasensitive Raman detection of molecular vibrational mode symmetry. To demonstrate the feasibility and effectiveness of our technique, we present both the theoretical framework and experimental results of dual-polarization QESRS. Our technique resulted in a noticeable reduction of noise on both parallel and orthogonal QESRS spectra as well as on the depolarization ratio spectra. These results validate the potential of our approach for achieving high-speed QESRS imaging with sub-shot-noise sensitivity.
We present a method for characterizing the intensity waveform, spectrum, frequency chirp, and spectral phase of picosecond pulses at a moderate repetition rate of ∼100 MHz. The proposed method exploits the intensity modulation at ∼10 GHz, which is slightly offset from the integer multiple of the repetition rate of the pulses. The modulated pulses are split into two, and one is measured by an optical spectrum analyzer, whose output is detected by a lock-in amplifier, while the other is directly detected by a photodiode and its output is used as a reference signal of the lock-in amplifier. In the experiment, we demonstrate the measurement of picosecond Ti:sapphire laser pulses to investigate frequency chirp induced by self-phase modulation. We anticipate that the proposed method will be useful for the characterization of various types of picosecond pulses.
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