arXiv subjects

Dijun Chen

Publications and source records attributed to Dijun Chen.

6 recordsLinked to original sources

arXiv2025

Overcoming the noise-tracking-bandwidth limits in Free-running Dual-Comb Interferometry

We present a straightforward method to extend the noise-tracking bandwidth for self-correction algorithms in free-running dual-comb interferometry, leveraging coherent-harmonic-enhanced dual-comb spectroscopy. As a proof of concept, we employed both this novel architecture and a conventional one to perform free-running dual-comb spectroscopy of a $\text{H}^{13}\text{C}^{14}\text{N}$ gas cell, demonstrating a 20-fold increase in tracking bandwidth at the same spectral resolution of 12.5 MHz. Since this approach improves the tracking bandwidth by generating harmonic centerbursts within an interferogram period, it decouples the tracking bandwidth from the repetition rate difference, thus avoiding spectral acquisition bandwidth narrowing. This significantly broadens the outlook for free-running dual-comb spectroscopy.

physics.optics↗

arXiv2025

Reducing Averaging Time in Dual-comb Spectroscopy via Phase-Patterned Higher-Repetition-Rate Pulses

Dual-comb spectroscopy (DCS) is a powerful Fourier-transform spectroscopic technique that provides high-speed, high-resolution, and broadband measurements without moving parts. However, the high peak power of mode-locked pulses limits the photodetector's dynamic range, resulting in a low signal-to-noise ratio (SNR) per acquisition. While coherent averaging can improve SNR, it sacrifices temporal resolution and demands stringent system stability. Here, we introduce a novel concept to enhance SNR by using phase-patterned higher-repetition-rate combs. We reinterpret the self-imaging process of comb spectrum from a new perspective on mode interference among sub-pulse trains As a proof-of-concept, we densified two 250-MHz frequency combs to 12.5-MHz mode spacings via phase modulation and performed DCS on an $\mathrm{H^{13}C^{14}N}$ gas cell, and compared the results with an emulated conventional 12.5-MHz DCS, demonstrating a 17-fold increase in mode amplitude. This concept is expected to be combined with ultra-high repetition rate combs, such as microcombs, and thereby deployed in practical applications that typically require spectral sampling spacings from hundreds of MHz to GHz range.

physics.optics↗

arXiv2014

Laser frequency offset locking via tripod-type electromagnetically induced transparency

We have demonstrated the laser frequency offset locking via the Rb tripod-type double dark resonances electromagnetically induced transparency (EIT) system. The influence of coupling fields power and detuning on the tripod-type EIT profile is detailed studied. In a wide coupling fields detuning range, the narrower EIT dip has an ultranarrow linewidth of 590 KHz, which is about one order narrower than the natural linewidth of Rb. Without the additional frequency stabilization of the coupling lasers, we achieve the relative frequency fluctuation of 60 KHz in a long time of ~2000s, which is narrower than the short-time linewidth of each individual laser.

physics.optics↗

arXiv2014

Realization of cavity linewidth narrowing via interacting dark resonances in a tripod-type electromagnetically induced transparency system

Cavity linewidth narrowing via double-dark resonances has been experimentally observed using the 87Rb Zeeman splitting sublevels. With the steep dispersion led by the interacting dark resonances in the tripodtype electromagnetically induced transparency system, we narrow the cavity linewidth to 250 KHz at room temperature. Furthermore, the position of this ultranarrow cavity linewidth could be tuned in a 60 MHz coupling field detuning range.

physics.optics↗

arXiv2013

Observation of Multi-Electromagnetically Induced Transparency in V-type Rubidium atoms

A detailed experimental investigation and theoretical analysis have been made in the V-type 85Rb atomic medium. Seven induced transparency windows, including a central double-peak-structure, have been observed experimentally when a coupling field and a probe field are applied into the ground and first excited states. By taking into account the hyperfine splitting of the excited state, our theoretical analysis gives good explanation for the observed phenomena.

physics.optics↗

arXiv2013

Tunable frequency reference by optical pumping-assisted intracavity V-type electromagnetically induced transparency

A tunable high resolution frequency reference is constructed using the narrowed cavity-linewidth by the optical pumping-assisted V-type electromagnetically induced transparency (EIT). At room temperature, the optical pumping effect will increase the transparency for the V-type EIT and therefore the cavity-linewidth can be narrowed apparently. For the seven EITs observed in our previous study, cavity-linewidth narrowing is observed in all of them. More importantly, we find that the cavity-linewidth can keep at 1.2MHz in a wide frequency range of 100MHz by utilizing the central EIT. This property provides a novel way for constructing high resolution tunable frequency reference via the intracavity EIT.

physics.optics↗