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Optical stretching is a powerful technique for the mechanical phenotyping of single suspended cells that exploits cell deformability as an inherent functional marker. Dual-beam optical trapping and stretching of cells is a recognized tool to investigate their viscoelastic properties. The optical stretcher has the ability to deform cells through optical forces without physical contact or bead attachment. In addition, it is the only method that can be combined with microfluidic delivery, allowing for the serial, high-throughput measurement of the optical deformability and the selective sorting of single specific cells. Femtosecond laser micromachining can fabricate in the same chip both the microfluidic channel and the optical waveguides, producing a monolithic device with a very precise alignment between the components and very low sensitivity to external perturbations. Femtosecond laser irradiation in a fused silica chip followed by chemical etching in hydrofluoric acid has been used to fabricate the microfluidic channels where the cells move by pressure-driven flow. With the same femtosecond laser source two optical waveguides, orthogonal to the microfluidic channel and opposing each other, have been written inside the chip. Here we present an optimized writing process that provides improved wall roughness of the micro-channels allowing high-quality imaging. In addition, we will show results on cell sorting on the basis of mechanical properties in the same device: the different deformability exhibited by metastatic and tumorigenic cells has been exploited to obtain a metastasis-cells enriched sample. The enrichment is verified by exploiting, after cells collection, fluorescence microscopy.

In this work we present an optical system for the supervision of the operation of an induction motor. We used a Mach- Zehnder interferometer and cyclic interferometer for the measurement of the vibrations produced by the motor motion and obtain a frequency spectrum via a Fourier transform of the signal. According to the spectrum, we can know the operation conditions of the induction motor. The optical system consist of the Interferometer, a data acquisition board and virtual instrument.

One of the main challenges of lab-on-a-chip technology is the on-chip integration of photonic functionalities by manufacturing optical waveguides for sensing biomolecules flowing in the microchannels. Such integrated approach has many advantages over traditional free-space optical sensing, such as compactness and portability, enhanced sensitivity and the possibility of parallel excitation at multiple points in the channel. Femtosecond laser pulses allow the microfabrication of optical waveguides into glass substrates, by exploiting nonlinear absorption in the focal volume, to induce a local refractive index modification. It is a direct, maskless, three-dimensional fabrication technique, which is particularly suited for waveguide inscription in already formed LOCs. In this work we report on the use of femtosecond laser pulses to inscribe optical waveguides in commercial fused silica LOCs in different geometries with respect to the microfluidic channels. We use the astigmatic beam shaping technique, previously developed by our group, to obtain waveguides with circular cross-section employing a 1 kHz repetition rate amplified Ti:sapphire laser. We demonstrate single mode waveguides in the visible with propagation losses lower than 1 dB/cm. Such waveguides provide highly selective excitation of small volumes of fluorescent solutions filling the channels and integrated collection of the fluorescent signal. Application to capillary electrophoresis will be discussed.

The fiber Raman amplifier employs the intrinsic properties of silica fiber to obtain the amplification, thus they use the transmission fiber as the amplification medium, where the gain is created along the transmission line. The amplification is realized by Stmulated Raman Scattering (SRS). This nonlinear process occurs when a sufficiently powerful pump is within the same fiber as the signal. In this paper, we showed experimental and numerical analysis of SRS in optical fibers. We obtain a continuous spectral when we plot the energy content in each Stokes sublines with the wavelength, which are self-pump between them. The numerical results are in agreement with the experimental results, just as the waveform in the time of optical fiber end and the energy is transferred from the signal pump to the Stokes sublines. With the simulations, we can obtain several parameters of this optical amplifier like the optical fiber effective length to obtain the amplification.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A multipoint fiber laser sensor, which consists of two cavities coupled based in three Bragg gratings of fiber optics and interrogated by the longitudinal mode beating frequency is presented. We used one Bragg grating (reference) and two Bragg gratings (sensors), which have the lowest reflection wavelength. The reference grating with the two sensors grating make two cavities: first one is the internal cavity which has 4230 m of length and the next one is the external cavity which has 4277 m of length. Measuring the laser beating frequency with a radio frequency (rf) analyzer for a resonance cavity and moving the frequency peaks when the another cavity are put in resonance, we prove that the arrangement can be used as a two points sensor for determining the difference of temperature or stress between these two points. On the other hand, one principal peak and three harmonics with bandwidths of 52 Hz were obtained with the rf analyzer. Their bandwidth was controlled by an intra-caivty fiber Optical Delay Line (ODL) and was measured with the rf analyzer.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present a design of an Er-doped fiber amplifier (EDFA) with high amplification. The purpose of the device is amplification of low power pulses from laser diodes to powers sufficiently high for investigations of optical fiber nonlinear processes. The optical amplifier consists of two stages. As the first stage we use the reflecting configuration where a signal is amplified twice in the same Er-doped fiber. The second stage works as a high power amplifier. The input pulses have pulse duration of 1 ns - 100 ns, and wavelength 1549.1 nm. The maximum amplification of this design is 50 dB. We obtained the output pulses with maximum power of 50 W. These pulses were used successfully to investigate the NOLM and SRS.