Interactions between light and various cells in cultures, such as bacteria or mammalian cells, are widely applied for optical sensors and optofluidic systems. These microorganisms need to be kept in proper aqueous media, referred to as buffers or cell culture media, that are required, respectively, for stable storage or delivering biochemical nutrients for their growth. When experiments or numerical analyses on optical devices are performed, the properties of these media are usually considered to be similar to those of pure water, with negligible influence of biochemical compounds on the medium’s optical properties. In this work, we investigated the transmission, material dispersion, and scattering properties of selected and widely used buffers and cell culture media. We show that the optical properties of these media may significantly vary from those of water. Well-defined properties of buffers and cell culture media are essential for proper design of various optical sensing or future optofluidic systems dealing with biological structures.

An all-normal dispersion supercontinuum generation in the range of 950 ÷ 1100 nm in photonic crystal fiber with core infiltrated with toluene is reported. The regular lattice hollow core photonic crystal fiber with a large core of 12 μm was designed and developed. The photonic crystal fiber core was selectively filled with toluene. The investigated fiber has normal dispersion in the wavelength range of 0.5 ÷ 2μm, while the absolute value of dispersion varies from 150 to 5 ps/nm/km in the range of 1 ÷ 2µm wavelength. The fiber nonlinear coefficient is 130 W⁻¹km⁻¹ as a result of the trade-off of high nonlinearity of toluene and a large mode area of the fundamental mode. The large mode area is required for the efficient delivery of high power pulses from large mode area input fiber in an all fiber system. As a pump source, a standard subpicosecond fiber laser emitting at 1030 nm with 10nJ pulse energy was used.

All-normal dispersion supercontinuum generation (SG) in a large hollow core photonic crystal fiber (PCF) infiltrated with carbon tetrachloride is studied experimentally. The PCF is optimized to have a flat normal dispersion in a broadband range (0.8–1.7 µm) varying from -150 to 0 ps/nm/km. The effective mode area at pump wavelength (λ=1030 nm) is as large as 42.2 µm² and readily meets the requirements for an all-fiber supercontinuum system. Infiltration of the core with carbon tetrachloride ensures a high nonlinear coefficient of the fiber equal to 22 1/W/km. Using an off-the-shelf 1030 nm fiber laser with 400 fs and 25 nJ input pulses, we generated an all-normal supercontinuum in the 850–1250 nm wavelength range.

A photonic crystal fiber made of fused silica glass and infiltrated with nitrobenzene (C ₆ H ₅ NO ₂ ) was proposed as a new nonlinear medium for supercontinuum generation (SG). The guiding properties of the fiber structure were studied numerically, including estimation of the effective refractive index, attenuation, and dispersion of the fundamental mode. Based on the obtained results, three optimized structures were selected and tested numerically for SG. With numerical simulations of nonlinear propagation, we demonstrated the feasibility of spectrally broad and coherent SG in the proposed structures. For the first we obtained a supercontinuum (SC) in the range of 0.8–1.8 µ m, for the second in the range of 0.8–2.1 µ m, and for the third 1.3–2.3 µ m. The pulse energy was in the range of 0.06–0.5 nJ while the pulse duration was 90 fs or 120 fs. For all structures an SC was formed in the first centimeter of the light propagation and conveniently allowed to assume short segments of the fibers. The proposed fibers are good candidates for all-fiber SC sources constituting an attractive alternative to glass-core fibers, since the nonlinearity of nitrobenzene is significantly higher than that of silica. The proposed solution may lead to new low-cost all-fiber optical systems for SG.

A photonic crystal fiber made of fused silica glass, infiltrated with chloroform (CHCl ₃ ), is proposed as a new source of supercontinuum (SC) light. Guiding properties in terms of effective refractive index, attenuation, and dispersion of the fundamental mode are studied numerically. As a result, two optimized structures are selected for and verified against SC generation in detail. The dispersion characteristic of the first structure is all-normal and equals −7 ps · nm ⁻¹ · km ⁻¹ at 0.92 μ m, while the dispersion characteristic of the second structure has the zero-dispersion wavelength at 1 μ m, and SC generation was demonstrated for the wavelength 1.03 μ m. We prove the possibility of coherent octave-wide SC generation in the wavelength range of 600–1260 nm and soliton fission based low-coherence flat SC in the wavelength range of 600–1400 nm, with 400 fs pulses and 0.8 nJ of energy in-coupled into the core of the studied structures. Proposed fibers are good candidates for all-fiber SC sources as an alternative to glass core fibers, since nonlinearity of CHCl ₃ is higher than silica and its toxicity is negligible. The proposed solution may lead to new low-cost all-fiber optical systems.

All-normal dispersion supercontinuum (ANDi SC) generation in a lead-bismuth-gallate glass solid-core photonic crystal fiber (PCF) with cladding air-holes infiltrated with carbon tetrachloride (CCl₄) is experimentally investigated and numerically verified. The liquid infiltration results in additional degrees of freedom that are complimentary to conventional dispersion engineering techniques and that allow the design of soft-glass ANDi fibers with an exceptionally flat near-zero dispersion profile. The unique combination of high nonlinearity and low normal dispersion enables the generation of a coherent, low-noise SC covering 0.93–2.5 µm requiring only 12.5 kW of pump peak power delivered by a standard ultrafast erbium-fiber laser with 100 MHz pulse repetition rate (PRR). This is a much lower peak power level than has been previously required for the generation of ANDi SC with bandwidths exceeding one octave in silica- or soft-glass fibers. Our results show that liquid-composite fibers are a promising pathway for scaling the PRR of ANDi SC sources by making the concept accessible to pump lasers with hundreds of megahertz of gigahertz PRR that have limited peak power per pulse but are often required in applications such as high-speed nonlinear imaging, optical communications, or frequency metrology. Furthermore, due to the overlap of the SC with the major gain bands of many rare-earth fiber amplifiers, our source could serve as a coherent seed for low-noise ultrafast lasers operating in the short-wave infrared spectral region.