Near-resonant Raman amplification in the rotational quantum wavepackets of nitrogen molecular ions generated by strong field ionization

Generation of laser-like narrow bandwidth emissions from nitrogen molecular ions generated in intense near- and mid-infrared femtosecond laser fields has aroused much interest because of the mysterious physics underlying such a phenomenon as well as the potential application of such an effect in atmospheric spectroscopic sensing. Here, we perform a pump-probe measurement on the nonlinear interaction of rotational quantum wavepackets of nitrogen molecular ions generated in mid-infrared (e.g., at a wavelength centered at 1580 nm) femtosecond laser fields with an ultrashort probe pulse whose broad spectrum overlaps both P- and R-branch rotational transition lines between the upper and lower electronic states. The results show that in the near-resonant conditions, stimulated Raman amplification can efficiently occur which converts the broad bandwidth ultrashort probe pulse into the narrow bandwidth laser-like beam. Our finding provides an insight into the physical mechanism of strong field induced lasing actions in atmospheric environment.Comment: 18 pages, 4 figure

Cancer patients' attitudes towards Chinese medicine: a Hong Kong survey

<p>Abstract</p> <p>Background</p> <p>This article reports a survey conducted in Hong Kong on the cancer patients' attitudes towards Chinese medicine treatment.</p> <p>Methods</p> <p>Cancer patients from three Chinese medicine clinics and one oncology clinic were interviewed with a structured questionnaire.</p> <p>Results</p> <p>Of a total of 786 participants included in the study, 42.9% used Western medicine only; 57.1% used at least one form of Chinese medicine; 5 participants used Chinese medicine only; and 56.5% used Chinese medicine before/during/after Western medicine treatment. Commonly used Western medicine and Chinese medicine treatments included chemotherapy (63.7%), radiotherapy (62.0%), surgery (57.6%), Chinese herbal medicine (53.9%) and Chinese dietary therapy (9.5%). Participants receiving chemotherapy used Chinese medicine (63.3%) more than those receiving any other Western medicine treatments. Spearman correlation coefficients showed that the selection of Chinese medicine was associated with the cancer type (r_s= -1.36; <it>P </it>< 0.001), stage (r_s= 0.178; <it>P </it>< 0.001), duration (r_s= -0.074; <it>P </it>= 0.037), whether receiving chemotherapy (r_s= 0.165; <it>P </it>< 0.001) and palliative therapy (r_s= 0.087; <it>P </it>= 0.015). Nearly two-thirds of the participants (N = 274) did not tell their physicians about using Chinese medicine. Over two-thirds of all participants (68.2%) believed that integrated Chinese and Western medicine was effective.</p> <p>Conclusion</p> <p>Chinese medicine is commonly used among Hong Kong cancer patients. The interviewed cancer patients in Hong Kong considered integrative Chinese and Western medicine is an effective cancer treatment.</p

An on-chip tunable micro-disk laser fabricated on Er3+ doped lithium niobate on insulator (LNOI)

We demonstrate a C-band wavelength-tunable microlaser with an Er3+ doped high quality (~1.02x10^6) lithium niobate microdisk resonator. With a 976 nm continuous-wave pump laser, lasing action can be observed at a pump power threshold as low as ~250 {\mu}W at room temperature. Furthermore, the microdisk laser wavelength can be tuned by varying the pump laser power, showing a tuning efficiency of ~-17.03 pm/mW at low pump power blow 13 mW, and 10.58 pm/mW at high pump power above 13 mW

On-chip arrayed waveguide grating fabricated on thin film lithium niobate

We design an on-chip 8-channel TFLN AWG and fabricate the device using photolithography assisted chemo-mechanical etching (PLACE) technique. We experimentally measure the transmission of the fabricated TFLN AWG near the central wavelength of 1550 nm. We obtain an on-chip loss as low as 3.32 dB, a single-channel bandwidth of 1.6 nm and a total-channel bandwidth of 12.8 nm. The crosstalk between adjacent channels was measured to be below -7.01 dB within the wavelength range from 1543 nm to 1558 nm, and the crosstalk between non-adjacent channels was below -15 dB

On-chip coherent beam combination of waveguide amplifiers on Er3+^{3+}-doped thin film lithium niobate

We demonstrate on-chip coherent beam combination of two waveguide amplifiers on Er$^{3+}$-doped thin film lithium niobate (Er: TFLN) platform. Our device is built based on an electro-optic modulator fabricated on Er: TFLN. The output power of the coherently combined amplifiers is measured as high as 12.9 mW, surpassing that of previous single waveguide amplifiers based on Er$^{3+}$-doped thin film lithium niobate platform

On-chip wavelength division multiplexing by angled multimode interferometer fabricated on erbium-doped thin film lithium niobate on insulator

Photonic integrated circuits based on erbium doped thin film lithium niobate on insulator has attracted broad interests with insofar various waveguide amplifiers and microlasers demonstrated. Wideband operation facilitated by the broadband absorption and emission of erbium ions necessitates the functional integration of wavelength filter and multiplexer on the same chip. Here a low-loss wavelength division multiplexer at the resonant pumping and emission wavelengths (~1480 nm and 1530~1560 nm) of erbium ions based on angled multimode interferometer, is realized in the erbium doped thin film lithium niobate on insulator fabricated by the photolithography assisted chemomechanical etching technique. The minimum on-chip insertion losses of the fabricated device are <0.7 dB for both wavelength ranges, and a 3-dB bandwidth of >20 nm is measured at the telecom C-band. Besides, direct visualization of the multimode interference pattern by the visible upconversion fluorescence of erbium ions compares well with the simulated light propagation in the multimode interferometer. Spectral tuning of the wavelength division multiplexer by structural design is also demonstrated and discussed.Comment: 11 pages, 5 figure