Digital cavities and their potential applications

Karki, Khadga Jung; Torbjörnsson, Magne; Widom, Julia R.; Marcus, Andrew H.; Pullerits, Tõnu

doi:10.1088/1748-0221/8/05/t05005

Cited by 20 publications

(22 citation statements)

References 10 publications

(21 reference statements)

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“…The signal from the APD and the PD are digitized simultaneously at the rate of 10 MSa/s (mega samples per second). The phase and the amplitude of the signal from the APD (two-photon PL) is analyzed with respect to the signal from the PD (reference) by using the algorithms of the generalized lock-in amplifier (GLIA) [43][44][45]. The two-photon excitation spectra are recorded as a function of the time delay between the two beams.…”

Section: Methodsmentioning

confidence: 99%

Two-photon excitation spectroscopy of 1,5–Diphenyl-1,3,5-hexatriene using phase modulation

Kumar

Karki

2019

J. Phys. Commun.

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We have used two-photon Fourier transform spectroscopy to investigate the first singlet excited state (S 1 ) of a prototypical polyene molecule 1,5-Diphenyl-1,3,5-hexatriene. As the S 1 state in the polyenes is a one-photon forbidden transition, the structure of its vibrational levels cannot be studied using resonant linear excitation. Although this level is accessible with two-photon excitation, previous studies done by using wavelength tunable pulsed lasers did not have enough resolution to investigate the details of the vibrational levels. In Fourier transform spectroscopy, one uses a pair of laser beams to excite the sample. The measurements are done by varying the time delay between the pulses. The spectral resolution is given by the inverse of the maximum time delay rather than the spectral width of the pulses. We have used the method to investigate the vibrational levels of the S 1 state. In our implementation, we have used phase modulation to carry out the measurements in the rotating frame, which requires less data points along the time delay thereby significantly reducing the measurement time.

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Section: Methodsmentioning

confidence: 99%

Two-photon excitation spectroscopy of 1,5–Diphenyl-1,3,5-hexatriene using phase modulation

Kumar

Karki

2019

J. Phys. Commun.

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“…1(b), is close to the response of the cavity to an ideal monochromatic signal. 1 However, when N c is increased to 5 × 10 7 , one observes wobbling of the maxima of the cavity response by few Hz. Figure 1(c) shows a 2 Hz shift of the maxima of the cavity response in the signals that are acquired half a seconds apart.…”

Section: A Precision Measurements Of High-frequency Signalsmentioning

confidence: 97%

“…1 According to Eq. (3) the fundamental resonance frequency can be tuned by either changing n or t. For example, if a signal is digitized at 100 MS/s (mega samples per second) and n is chosen to be 100 then f 0 = 1 MHz, and if n is chosen to be 90 then f 0 = 1.1111... MHz.…”

Section: Theorymentioning

confidence: 99%

“…This design of the digital cavity is expected to achieve extremely high Q-factors >10 9 with reasonable memory requirements. 1 A drawback of such a design is that normal digitizing cards that usually have a fixed clock cannot be used to build a finely tunable digital cavity. However, in applications for which a Q-factor of less than 10 8 suffices, one can use digital tuning.…”

Section: Theorymentioning

confidence: 99%

“…This is also an advantage because one can apply multiple cavities simultaneously to the signal to extract different Fourier components. 1 Moreover, for applications like the software defined radio or the detection of faint radio/microwave frequencies, the external reference is not available so normal LIA cannot be used.…”

Section: Advantages and Limitationsmentioning

confidence: 99%

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Generalized lock-in amplifier for precision measurement of high frequency signals

Sakurai

Liu

et al. 2013

Review of Scientific Instruments

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We herein formulate the concept of a generalized lock-in amplifier for the precision measurement of high frequency signals based on digital cavities. Accurate measurement of signals higher than 200 MHz using the generalized lock-in is demonstrated. The technique is compared with a traditional lock-in and its advantages and limitations are discussed. We also briefly point out how the generalized lock-in can be used for precision measurement of giga-hertz signals by using parallel processing of the digitized signals.

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Differentiation of True Nonlinear and Incoherent Mixing of Linear Signals in Action-Detected 2D Spectroscopy

2019

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Phase modulation and phase cycling schemes have been commonly used in electronic two-dimensional (2D) spectroscopy where the observables are incoherent signals such as fluorescence or photocurrent. Although the methods have distinct advantages compared to the coherent signal-detected 2D spectroscopy in sensitivity, possibility to measure spectra from isolated quantum systems and direct visualization of the contributions from the different states to the action signals, and ambiguities in interpreting the spectra have emerged. Recent reports have shown that apart from the nonlinear signals from the four pulse interactions, mixing of the linear signals due to nonlinear population dynamics during the long measurement time of the action signals can also contribute to the measured 2D spectra. Exciton–exciton annihilation has been considered to play a major role in the mixing of the linear signals. Thus, it has become important to further characterize the origin of the measured signals. Here, using a nonperturbative simulation of the 2D spectra based on the time evolution of the density matrix in the Lindblad form, we show that the exciton–exciton annihilation contributes to the measured signal only if the quantum yields of the different excited states are not the same. In these cases, the mixed signals can be distinguished from the true nonlinear signals if the phases are measured with respect to the linear signals. In action-detected 2D spectra, the mixed signals have a π phase shift relative to the true nonlinear signals. A detailed discussion on the experimental implementations of the schemes used in the simulations is also provided.

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Digital cavities and their potential applications

Cited by 20 publications

References 10 publications

Two-photon excitation spectroscopy of 1,5–Diphenyl-1,3,5-hexatriene using phase modulation

Two-photon excitation spectroscopy of 1,5–Diphenyl-1,3,5-hexatriene using phase modulation

Generalized lock-in amplifier for precision measurement of high frequency signals

Differentiation of True Nonlinear and Incoherent Mixing of Linear Signals in Action-Detected 2D Spectroscopy

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