scholarly journals Ultrafast electro-optic light with subcycle control

Science ◽  
2018 ◽  
Vol 361 (6409) ◽  
pp. 1358-1363 ◽  
Author(s):  
David R. Carlson ◽  
Daniel D. Hickstein ◽  
Wei Zhang ◽  
Andrew J. Metcalf ◽  
Franklyn Quinlan ◽  
...  
Keyword(s):  
High Speed ◽  
Near Infrared ◽  
Continuous Wave ◽  
Mode Locking ◽  
Light Sources ◽  
Electro Optic ◽  
High Pulse ◽  
Optical Cycle ◽  
Rapid Transients ◽  
And Control

Light sources that are ultrafast and ultrastable enable applications like timing with subfemtosecond precision and control of quantum and classical systems. Mode-locked lasers have often given access to this regime, by using their high pulse energies. We demonstrate an adaptable method for ultrastable control of low-energy femtosecond pulses based on common electro-optic modulation of a continuous-wave laser light source. We show that we can obtain 100-picojoule pulse trains at rates up to 30 gigahertz and demonstrate sub–optical cycle timing precision and useful output spectra spanning the near infrared. Our source enters the few-cycle ultrafast regime without mode locking, and its high speed provides access to nonlinear measurements and rapid transients.

Electric field controlled near-infrared high-speed electro-optic switching modulator integrated with 2D MgO

2020 ◽  
Vol 45 (16) ◽  
pp. 4611 ◽  
Author(s):  
Ch. N. Rao ◽  
Dnyandeo Pawar ◽  
Umesh T. Nakate ◽  
Radhamanohar Aepuru ◽  
XingGao Gui ◽  
...  
Keyword(s):  
Electric Field ◽  
High Speed ◽  
Near Infrared ◽  
Electro Optic

Pulsed electro-optic modulation for efficient, active continuous-wave laser mode-locking

1993 ◽  
Vol 71 (1-2) ◽  
pp. 1-4 ◽  
Author(s):  
C. J. Flood ◽  
G. Giuliani ◽  
H. M. van Driel
Keyword(s):  
Continuous Wave ◽  
Laser Pulses ◽  
Mode Locking ◽  
Continuous Wave Laser ◽  
Drive Power ◽  
Active Mode ◽  
Broad Bandwidth ◽  
Electro Optic ◽  
Narrow Bandwidth ◽  
Electrical Pulses

We demonstrated efficient active mode-locking of a Nd:YAG laser using broad bandwidth, pulsed electro-optic modulation. A 10 GHz, LiTaO3 traveling wave phase modulator, driven by 300 ps FWHM electrical pulses with less than 1 mW of drive power, was used to generate detector-limited, mode-locked laser pulses of less than 50 ps duration at 76 MHz. Shorter modulator drive pulses are possible and near bandwidth-limited mode-locked pulses should be attainable. The use of pulsed modulation rather than conventional sinusoidal modulation permits both pulse width and pulse build-up time reductions and generally makes active mode-locking competitive with passive mode-locking for relatively low-gain and narrow-bandwidth lasers.

scholarly journals Computational Laser Spectroscopy in a Biological Tissue

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
M. Gantri ◽  
H. Trabelsi ◽  
E. Sediki ◽  
R. Ben Salah
Keyword(s):  
Biological Tissue ◽  
Near Infrared ◽  
Continuous Wave ◽  
Light Transmission ◽  
Short Pulse ◽  
Control Volume ◽  
External Source ◽  
Time Dependent ◽  
Infrared Light ◽  
Light Sources

We present a numerical spectroscopic study of visible and infrared laser radiation in a biological tissue. We derive a solution of a general two-dimensional time dependent radiative transfer equation in a tissue-like medium. The used model is suitable for many situations especially when the external source is time-dependent or continuous. We use a control volume-discrete ordinate method associated with an implicit three-level second-order time differencing scheme. We consider a very thin rectangular biological-tissue-like medium submitted to a visible or a near infrared light sources. The RTE is solved for a set of different wavelength source. All sources are assumed to be monochromatic and collimated. The energetic fluence rate is computed at a set of detector points on the boundaries. According to the source type, we investigate either the steady-state or transient response of the medium. The used model is validated in the case of a heterogeneous tissue-like medium using referencing experimental results from the literature. Also, the developed model is used to study changes on transmitted light in a rat-liver tissue-like medium. Optical properties depend on the source wavelength and they are taken from the literature. In particular, light-transmission in the medium is studied for continuous wave and for short pulse.

scholarly journals Optical Coherence Tomography for Three-Dimensional Imaging in the Biomedical Field: A Review

2021 ◽  
Vol 9 ◽  
Author(s):  
Shu Zheng ◽  
Yanru Bai ◽  
Zihao Xu ◽  
Pengfei Liu ◽  
Guangjian Ni
Keyword(s):  
Optical Coherence Tomography ◽  
High Speed ◽  
Near Infrared ◽  
Polarization State ◽  
Three Dimensional ◽  
Biological Research ◽  
Light Sources ◽  
Optical Coherence ◽  
Biomedical Field

Optical coherence tomography (OCT) has become a novel approach to noninvasive imaging in the past three decades, bringing a significant potential to biological research and medical biopsy in situ, particularly in three-dimensional (3D) in vivo conditions. Specifically, OCT systems using broad bandwidth sources, mainly centered at near-infrared-II, allow significantly higher imaging depth, as well as maintain a high-resolution and better signal-to-noise ratio than the traditional microscope, which avoids the scattering blur and thus obtains more details from delicate biological structures not just limited to the surface. Furthermore, OCT systems combined the spectrometer with novel light sources, such as multiplexed superluminescent diodes or ultra-broadband supercontinuum laser sources, to obtain sub-micron resolution imaging with high-speed achieve widespread clinical applications. Besides improving OCT performance, the functional extensions of OCT with other designs and instrumentations, taking polarization state or birefringence into account, have further improved OCT properties and functions. We summarized the conventional principle of OCT systems, including time-domain OCT, Fourier-domain OCT, and several typical OCT extensions, compared their different components and properties, and analyzed factors that affect OCT performance. We also reviewed current applications of OCT in the biomedical field, especially in hearing science, discussed existing limitations and challenges, and looked forward to future development, which may provide a guideline for those with 3D in vivo imaging desires.

scholarly journals A DAQ-Device-Based Continuous Wave Near-Infrared Spectroscopy System for Measuring Human Functional Brain Activity

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Gang Xu ◽  
Xiaoli Li ◽  
Duan Li ◽  
Xiaomin Liu
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Continuous Wave ◽  
Mental Arithmetic ◽  
Valsalva Maneuver ◽  
Light Sources ◽  
Functional Near Infrared Spectroscopy ◽  
Quadrature Demodulation ◽  
Custom Made

In the last two decades, functional near-infrared spectroscopy (fNIRS) is getting more and more popular as a neuroimaging technique. The fNIRS instrument can be used to measure local hemodynamic response, which indirectly reflects the functional neural activities in human brain. In this study, an easily implemented way to establish DAQ-device-based fNIRS system was proposed. Basic instrumentation components (light sources driving, signal conditioning, sensors, and optical fiber) of the fNIRS system were described. The digital in-phase and quadrature demodulation method was applied in LabVIEW software to distinguish light sources from different emitters. The effectiveness of the custom-made system was verified by simultaneous measurement with a commercial instrument ETG-4000 during Valsalva maneuver experiment. The light intensity data acquired from two systems were highly correlated for lower wavelength (Pearson’s correlation coefficientr= 0.92,P< 0.01) and higher wavelength (r= 0.84,P< 0.01). Further, another mental arithmetic experiment was implemented to detect neural activation in the prefrontal cortex. For 9 participants, significant cerebral activation was detected in 6 subjects (P< 0.05) for oxyhemoglobin and in 8 subjects (P< 0.01) for deoxyhemoglobin.

scholarly journals The Effect of Yoga Meditation Practice on Young Adults’ Inhibitory Control: An fNIRS Study

2021 ◽  
Vol 15 ◽  
Author(s):  
Dongdong Jiang ◽  
Zongyu Liu ◽  
Guoxiao Sun
Keyword(s):  
Young Adults ◽  
Inhibitory Control ◽  
Near Infrared ◽  
Continuous Wave ◽  
Control Group ◽  
Promoting Effect ◽  
Infrared Spectrometer ◽  
Study Participants ◽  
And Control ◽  
Yoga Meditation

Objectives: The present study aimed to test the effect of yoga meditation (YoMed) practice on inhibitory control of young adults.Methods: A total of 50 participants (23 male, 21–28 years old) from a university in Jinan, Shandong Province were enrolled in this study. Participants were randomly assigned to a YoMed group or a Control group. Participants’ basic information, physical activity, and inhibitory control were measured. A multi-channel continuous-wave near-infrared spectrometer was used to monitor the brain’s hemodynamic responses.Results: After the intervention, we found significant differences in Flanker tasks between the YoMed group and Control group. The accuracy in the YoMed group was higher than those in the Control group (p &lt; 0.05). Analysis of fNIRS data showed that oxyhemoglobin (oxy-Hb) levels in the prefrontal cortex (PFC) increased in the YoMed group during the Flanker tasks after the YoMed intervention.Conclusion: YoMed has a temporarily promoting effect on the brain activation of young adults. It is an effective and appropriate exercise to improve the inhibitory control of young adults.

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