Tunable colloidal quantum dot distributed feedback lasers integrated on a continuously chirped surface grating

Piezo-Actuated One-Axis Vibrational Patterning for Mold-Free Continuous Fabrication of High-Precision Period-Programmable Micro- and Nanopatterns

We present a mold-free high-resolution nanopatterning technology named piezo-actuated one-axis vibrational patterning (POP) that enables continuous and scalable fabrication of micro- and nanopatterns with precisely programmable periods and dimensions. POP utilizes the piezoelectric stack-actuated high-precision uniaxial vibration of a flat, pattern-free rigid tool edge to conduct sub-50 nm-periodic indentations on various compliant substrates laterally fed underneath. By controlling the tool vibration frequency, tool temperature, and substrate feed rate and by combining sequential tool strokes along multiple directions, diverse functional micro- and nanopatterns with variable periods and depths and multidimensional profiles can be continuously created without resorting to mold prefabrication. With its simple but universal principle, excellent scalability, and versatile processability, POP can be practically applied to many functional devices particularly requiring large-area micro- and nanopatterns with specifically designed periods and dimensions.

Distributed feedback organic lasing in photonic crystals

Considerable research efforts have been devoted to the investigation of distributed feedback (DFB) organic lasing in photonic crystals in recent decades. It is still a big challenge to realize DFB lasing in complex photonic crystals. This review discusses the recent progress on the DFB organic laser based on one-, two-, and three-dimensional photonic crystals. The photophysics of gain materials and the fabrication of laser cavities are also introduced. At last, future development trends of the lasers are prospected.

Tunable polymer lasing in chirped cavities

Continuously tunable polymer lasing was achieved in one-dimensional, two-dimensional, and compound chirped cavities. The chirped cavity was simply fabricated by using interference lithography and spin coating. Two-dimensional and compound chirped cavities were obtained by employing oblique exposure and double exposure, respectively. The tunability range of two-dimensional chirped cavities was much wider than that of one-dimensional chirped cavities, which varied from 557 nm to 582 nm. The interaction between lasing modes was studied in the compound cavity by introducing an additional nanostructure into the two-dimensional chirped cavities. The threshold of the compound chirped cavities changed with the coupling strength between lasing modes. These results may be helpful for designing compact polymer laser sources.

Femtosecond Thin-Film Laser Amplifiers Using Chirped Gratings

Ultrafast injection-locked amplification is achieved by sending femtosecond supercontinuum pulses into a polymeric thin film coated on a distributed feedback (DFB) microcavity consisting of chirped gratings. The spatial variation of the grating period led to the resonance of the DFB microcavity at different wavelengths for injection at different locations. This enables convenient and continuous tuning of the amplification spectrum by displacing the grating structures. The large area of the grating structures enabled large tuning range. The amplified spectrum can be continuously tuned from 545 to 580 nm through sliding the grating structures by about 3.5 mm. Sub-1 ps lifetime has been measured for the amplification process with a net amplification factor as large as 33. Injection locking enabled high-quality control of the divergence and transverse mode of the output laser beam.