No abstract

Dynamic modulation of soft helix in terms of the molecular organization, handedness, and pitch length could result in a sophisticated control over its functions, opening numerous possibilities toward the exploration of previously unidentified applications. Here, we report a dynamic and reversible transformation of a soft helical superstructure among the helicoidal (molecules orthogonal to helical axis), heliconical (molecules oblique to the helical axis, i.e., oblique helicoidal), and their inverse helices, together with a tunability on the helical pitch, by combining electrical and optical manipulations. This multistate transformation depends on a matching of the temperature, the strength of external stimuli, and the bend and twist elastic effects of the system. A laser emission with tunable wavelength and polarization, and prescribed micropatterns formed by any aforementioned architectures were achieved.

Active engineering and modulation of optical spectra in a remote and fully reversible light is urgently desired in photonics, chemistry, and materials. However, the real-time regulation of multiple optical information such as wavelength, bandwidth, reflectance, and polarization is still a longstanding issue due to the lack of an appropriate photoresponsive candidate. Herein, we propose an additional “degree-of-freedom (DOF)” in a photo-modulated soft helix, and build up an unprecedented inhomogeneous helical pitch length with light-reconfiguring property, fatigue resistance, and reversibility. For the working model, the intrinsic chiral photoswitch LBC5 is employed as an actuator to modulate the helical pitch length, which is proportional to the irradiation intensity, and the unique broadband absorbance photo-modulator BTA-C5 is incorporated as an attenuator of the transmitted light to decrease its intensity along the sample thickness, therefore successfully adding another controlled DOF on the pitch length distribution (i.e., homogeneous or inhomogeneous) apart from the common soft helix with only a single DOF on the pitch length. The absorbance photo-modulator BTA-C5 with a unique variable broadband absorption enables the light to reconfigure the helical pitch from homogeneous to inhomogeneous, thereby achieving the robust fatigue-resistance establishment of reversible spectral programming. The established light-reconfigurable inhomogeneous helical pitch with the photoresponsive modulator BTA-C5 can provide a breakthrough to control absorbance and chirality, especially for dynamically broadening and narrowing the bandwidth on demand, and further enable the ever-desired broadband NIR circularly polarized luminescence (CPL) with a high dissymmetry factor g lum of up to 1.88. The cutting-edge photoswitchable inhomogeneous soft helical pitch provides access to multi-freedom control in soft materials, optics, biophotonics, and other relevant fields.

Dynamic and multi‐dimensional manipulation of laser emission with light allows for optical coding, computing, and imaging photonic chips. However, the coupling balance between photonic resonance and transmission is a formidable challenge due to the uncontrollable chiral microcavity with photo‐reversibility, which is limited to the multi‐freedom of the laser with sustainable and repeatable output beams. Herein, a helical superstructure system with a unique intrinsic chiral photoswitch is developed for resolving the always pendent problems on organized defects in the microcavity. The unique intrinsic chirality based on the photoswitchable system allows laser emission with a sharp and narrow band‐width, with both remarkable thermodynamic stability and robust fatigue‐resistance. A quadri‐dimensional manipulable laser, featuring wavelength‐tunability, wavefront‐shaping, spin angular momentum (SAM), and orbital angular momentum (OAM), is successfully established with the assistance of the photoresponsive intrinsic chiral superstructure with photoreversibility. This technology marks an important milestone, and sketches a future framework for the realms of nanophotonic information encoding, security imprinting, and integrated photonics.

Multidimensional and large‐scale parallel manipulation of light, especially on‐demand tailoring of the working frequency and spatial phase front, is highly pursued in modern optics. Here, broadband tunable planar optics is demonstrated by electrically driving the nanohelix of photopatterned heliconical cholesterics. By preprogramming the initial orientation of the helixes using a dynamic‐mask photoalignment technique, spatial geometric phases can be arbitrarily encoded to the reflected light in a reconfigurable way. Due to the reversible electrically variant pitch of the heliconical superstructures, the reflective Bragg band can be precisely selected in the range from 380 to 1550 nm. In addition to wavelength selection and geometric phase modulation, spatial amplitude modulation and spin reversion can be further expected. This may offer a platform for full‐dimensional manipulation of light, including wavelength/frequency, phase, amplitude, time, and spin, thus upgrading optical information processing techniques.