Comparison of the performance of photonic band-edge liquid crystal lasers using different dyes as the gain medium

Mowatt, Carrie; Morris, Stephen M.; Song, Myoung Hoon; Wilkinson, Timothy D.; Friend, Richard H.; Coles, H. J.

doi:10.1063/1.3284939

Cited by 79 publications

(37 citation statements)

References 33 publications

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“…For laser applications, the order parameter of a dye is not as crucial to its practical use as it is for display applications, although the orientation of the TDM of a dye can affect the lasing wavelength, [55] and the order parameter can determine the efficiency of the laser. [56] For lasing to occur in a liquid crystal laser, a high molar absorption coefficient, a high quantum yield of emission and a high degree of stability and solubility are all important characteristics, [55] and as such, studies have focused on different dye classes to those above, such as merocyanines, [57] pyrenes, [58] anthracenes [55] and pyrromethenes. [57] Some examples of structures from these dye classes are shown in Figure 5 …”

Section: Other Dyesmentioning

confidence: 99%

Dyes as guests in ordered systems: current understanding and future directions

Sims

2016

Liquid Crystals

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The optical properties of dyes dissolved in liquid crystals have led to their proposed use in a diverse range of practical applications. Such guest-host systems are typically required to fulfil a range of criteria relating to their absorption properties, degree of alignment and stability, but concurrently satisfying these requirements has proven a barrier to their widespread use. In this article, many of the proposed applications and their requirements are discussed, and an outline of some of the most prevalent classes of dye proposed in the context of guest-host systems is given, along with a summary of recent reports of dyes that exhibit thermotropic mesophases. Theoretical approaches to describing the alignment within guest-host systems are outlined, and possible strategies for the future rational design of guest-host systems are discussed. ARTICLE HISTORY

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Section: Other Dyesmentioning

confidence: 99%

Dyes as guests in ordered systems: current understanding and future directions

Sims

2016

Liquid Crystals

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“…One strategy relies on the fact that lasing is favored in the bandedge mode that overlaps most with the emission spectrum of the gain medium. 14 Such switching was previously demonstrated by thermally shifting the PBG of the CLC. 15 Unfortunately, the thermal mode switching is usually accompanied by shifts of the bandedges and the resulting lasing wavelength.…”

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confidence: 99%

Electrically assisted bandedge mode selection of photonic crystal lasing in chiral nematic liquid crystals

Wang

Chen

Yang

et al. 2018

Applied Physics Letters

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Selection of the bandedge lasing mode of a photonic crystal laser has been realized in a fluorescent dye doped chiral nematic liquid crystal by exerting electrical control over the mode competition. The bandedge lasing can be reversibly switched from the short-wavelength edge mode to the long-wavelength edge mode by applying a voltage of only 20 V, without tuning the bandgap. The underlying mechanism is the field-induced change in the order parameter of the fluorescent dye in the liquid crystal. The orientation of the transition dipole moment determines the polarization state of the dye emission, thereby promoting lasing in the bandedge mode that favors the emission polarization. Moreover, the dynamic mode-selection capability is retained upon polymer-stabilizing the chiral nematic liquid crystal laser. In the polymer-stabilized system, greatly improved stability and lasing performance are observed. The lasing behavior in chiral nematic liquid crystals (CLC) has been extensively studied over the past decades due to its favorable properties, such as low threshold, high tunability, and the ease of fabrication. [1][2][3] CLC is a particular class of liquid crystals in which the molecules self-assemble into one-dimensional helices, typically formed by mixing a nematic liquid crystal with a chiral agent. The concentration and twisting power of the chiral agent determine the helical pitch (p). Such a periodic chiral structure can be regarded as a one-dimensional photonic crystal for a circularly polarized probe with the same handedness as that of the structure. The associated photonic bandgap (PBG) is located at λ c = n c ⋅p with a bandwidth Δλ = Δn⋅p, where n c and Δn are the average refractive index and birefringence of the CLC, respectively. Resonances occur at the two bandedges: long wavelength edge (LWE) and short wavelength edge (SWE); the corresponding wavelengths are λ LWE = n e ⋅p and λ SWE = n o ⋅p, respectively, where n e is the extraordinary refractive index and n o is the ordinary refractive index. At the bandedge, the group velocity of light approaches zero, and hence the density of states is significantly enhanced. 4,5 In the presence of a gain medium, laser action can occur at the photonic bandedge(s) through optical excitation-usually termed the bandedge lasing. To date, a great deal of effort has been devoted to achieve a wide dynamic tuning range of the lasing wavelength with the aid of external inputs, such as electric field 6,7 , heat 8,9 , light 10 , and mechanical stress 11 . However, the post-

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“…8. In previous reports, only the band-edge laser has been obtained in the planar texture of CLC [29][30][31]. Interestingly, we observe RLs and not band-edge lasers in the planar texture of the CLC.…”

Section: Resultsmentioning

confidence: 96%

Band-gap-tailored random laser

Xing

Wei

et al. 2018

Photon. Res.

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A band-gap-tailored random laser with a wide tunable range and low threshold through infrared radiation is demonstrated. When fluorescent dyes are doped into the liquid crystal and heavily doped chiral agent system, we demonstrate a wavelength tuning random laser instead of a side-band laser, which is caused by the combined effect of multi-scattering of liquid crystal (LC) and band-gap control. Through rotating the infrared absorbing material on the side of the LC cell, an adjustable range for random lasing of 80 nm by infrared light irradiation was observed.

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Comparison of the performance of photonic band-edge liquid crystal lasers using different dyes as the gain medium

Cited by 79 publications

References 33 publications

Dyes as guests in ordered systems: current understanding and future directions

Dyes as guests in ordered systems: current understanding and future directions

Electrically assisted bandedge mode selection of photonic crystal lasing in chiral nematic liquid crystals

Band-gap-tailored random laser

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