The theoretical and experimental analysis of the open resonator with the reflection diffraction comb grating has been presented.
This resonator has excitation where is close to the monofrequency mode. This results may be used for the elaboration of mm-wave
quasi-optical devices such as generators, mixer, converter, wavemeters and others. 相似文献
Hexagonal Ca5(PO4)3F, known as natural crystal fluorapatite and oldest host‐crystal for Ln3+‐lasant ions, is presented as a Raman‐active material. High‐order Raman‐induced χ(3)‐nonlinear processes are discovered in natural crystals of fluorapatite under picosecond pumping at 1.064 μm and 0.532 μm wavelength. A multitude of Stokes and anti‐Stokes components is generated in the ultraviolet, visible and near‐infrared spectral region by stimulated Raman scattering (SRS) and Raman four‐wave mixing (FWHM), resulting in a frequency comb with a width of 520 THz. The spectral lines are identified and attributed to the ν1(Ag) vibration mode of the tetrahedral [PO4] units which is related to a Raman shift of ωSRS ≈ 965 cm−1. The first Stokes steady‐state Raman gain coefficient in the near‐infrared spectral range is estimated to be >0.38 cm·GW−1. Finally, a short review of SRS‐promoting vibration modes and observed χ(3)‐ nonlinear interactions in all known SRS‐active natural crystals (minerals) is given.
Bottlebrush polymers are synthesized using a tandem ring‐opening polymerization (ROP) and ring‐opening metathesis polymerization (ROMP) strategy. For the first time, ROP and ROMP are conducted sequentially in the same pot to yield well‐defined bottlebrush polymers with molecular weights in excess of 106 Da. The first step of this process involves the synthesis of a polylactide macromonomer (MM) via ROP of d ,l ‐lactide initiated by an alcohol‐functionalized norbornene. ROMP grafting‐through is then carried out in the same pot to produce the bottlebrush polymer. The applicability of this methodology is evaluated for different MM molecular weights and bottlebrush backbone degrees of polymerization. Size‐exclusion chromatographic and 1H NMR spectroscopic analyses confirm excellent control over both polymerization steps. In addition, bottlebrush polymers are imaged using atomic force microscopy and stain‐free transmission electron microscopy on graphene oxide.
