High-flux entangled photon source is the key resource for quantum optical study and application. Here it is realized in a lithium niobate on isolator (LNOI) chip, with 2.79×10 11 Hz/mW photon pair rate and 1.53×10 9 Hz/nm/mW spectral brightness. These data are boosted by over two orders of magnitude compared to existing technologies. A 130-nm broad bandwidth is engineered for 8-channel multiplexed energy-time entanglement. Harnessed by high-extinction frequency correlation and Franson interferences up to 99.17% visibility, such energy-time entanglement multiplexing further enhances high-flux data rate, and warrants broad applications in quantum information processing on a chip.
Optical parametric oscillators (OPOs) can downconvert the pump laser to longer wavelengths with octave separation via
χ
(
2
)
, which is widely used for laser wavelength extension including mid-infrared (MIR) generation. Such a process can be integrated in monolithic resonators, being compact and low in threshold. In this work, we show that the monolithic
χ
(
2
)
mini-OPO can also be used for optical frequency comb generation around 2096 nm and enters the boundary of MIR range. A new geometry called an optical superlattice box resonator is developed for this realization with near-material-limited quality factor of
4.0
×
10
7
. Only a continuous-wave near-infrared pump laser is required, with OPO threshold of 80 mW and output power up to 340 mW. Revival temporal profiles are measured at a detectable repetition frequency of 1.426 GHz, and narrow beat note linewidth of less than 10 Hz shows high comb coherence. These results are in good agreement with our simulation for a stable comb generation. Such an OPO-based comb source is useful for carbon dioxide sensing or the mine prospect applications and can be generalized to longer MIR wavelengths for general gas spectroscopy.
Narrow-linewidth lasers are essential for various applications, but are limited by their size, weight, power, and cost requirements. Here we demonstrate a self-injection locked diode laser fabricated with a high quality factor fiber Fabry–Perot resonator, with a 145 Hz free-running linewidth. The locking scheme is all-fiber for plug-and-play operation. White frequency noise of
50
H
z
2
/
H
z
is measured with over 42 dB reduction from the low-cost TO-can distributed feedback laser diode, and shows its wide applications in a compact and cost-effective way.
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