scholarly journals Quasi-Distributed Active-Mode-Locking Laser Interrogation with Multiple Partially Reflecting Segment Sensors

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4128
Author(s):  
Chang Park ◽  
Gyeong Kim ◽  
Suck Hong ◽  
Hwi Lee ◽  
Chang-Seok Kim
Keyword(s):  
Laser Cavity ◽  
Length Change ◽  
Mode Locking ◽  
Segment Length ◽  
Length Variation ◽  
Active Mode ◽  
Distributed Sensor ◽  
Fabry Perot ◽  
New Type ◽  
The Difference

A new type of quasi-distributed sensor system is implemented using an active mode locking (AML) laser cavity with multiple partially reflecting segments. The mode locking frequency of the AML laser is linearly proportional to the overall lasing cavity length. To implement multiple resonators having multiple reflection points installed in a sensing fiber, two types of partial reflectors (PRs) are implemented for an in-line configuration, one with fiber Bragg grating and the other with a fiber Fabry–Perot interferometer. Since the laser has oscillated only when the modulation frequencies for the mode locking frequency match with the corresponding resonator lengths, it is possible to read the multiple partially reflecting segments along the sensing fiber. The difference between two corresponding mode locking frequencies is changing proportionally with the segment length variation between two PRs upon strain application. The segment length change caused by the applied strain can be successfully measured with a linear sensitivity between mode locking frequency and displacement, linearity over 0.99, and spatial position resolution below meter order.

Differences in distensibility between the anterior and posterior walls of the left ventricle in dogs

1991 ◽  
Vol 69 (3) ◽  
pp. 334-340
Author(s):  
Zhao-Nian Zhou ◽  
Sheng-Jing Dong ◽  
Eldon R. Smith ◽  
John V. Tyberg
Keyword(s):  
Left Ventricle ◽  
Length Change ◽  
Posterior Wall ◽  
Anterior Wall ◽  
Left Ventricular ◽  
Transmural Pressure ◽  
Segment Length ◽  
Anesthetized Dogs ◽  
Pericardial Pressure ◽  
The Difference

Nonuniformity of myocardial systolic and diastolic performance in the normal left ventricle has been recognized by a number of investigators. Lack of homogeneity in diastolic properties might be caused by or related to differences in the distensibility of different regions of the left ventricular (LV) wall. Thus, we compared the end-diastolic transmural pressure–strain relations in both the anterior and posterior LV walls in seven anesthetized dogs during two interventions (pulmonary artery constriction and aortic constriction). Transmural pressure was defined as the difference between LV intracavitary pressure and local pericardial pressure. LV pressure was measured using a micromanometer; pericardial pressures over the LV anterior and posterior wails were measured with balloon transducers. Circumferentially oriented pairs of sonomicrometer crystals were implanted in the midwall of the anterior and posterior walls of the LV to measure segment lengths. Strains were calculated as (L – L0)/L0, where L was the instantaneous segment length and L0 was the segment length when transmural pressure was zero. The pattern of end-diastolic transmural pressure–strain relations was similar in ail dogs. The change in strain in the posterior wall was always greater than that in the anterior wall. Opening the pericardium did not affect the difference in distensibility of the anterior and posterior walls. The results suggest that the posterior wall is more compliant than the anterior wall (that is, for a given difference in transmural pressure, the local segment length change of the posterior wall was greater). This seems consistent with other observations, which suggest that the posterior wall might make a greater contribution to diastolic filling.Key words: regional ventricular function, diastolic suction, elastic properties.

Active mode locking laser interrogation for multiple fiber Fabry-Perot interferometer sensing heads

2018 ◽  
Author(s):  
Chang Hyun Park ◽  
Gyeong Hun Kim ◽  
Hwi Don Lee ◽  
Youngjoo Chung ◽  
Chang-Seok Kim
Keyword(s):  
Mode Locking ◽  
Active Mode ◽  
Fabry Perot

Quasi-distributed fiber sensor using active mode locking laser cavity with multiple FBG reflections

2017 ◽  
Author(s):  
Chang Hyun Park ◽  
Gyeong Hun Kim ◽  
Chang-Seok Kim ◽  
Hwi Don Lee ◽  
Youngjoo Chung
Keyword(s):  
Laser Cavity ◽  
Mode Locking ◽  
Fiber Sensor ◽  
Active Mode

Characterization and experimental verification of actively mode-locked erbium doped fiber laser utilizing ring cavity

2020 ◽  
Vol 87 (9) ◽  
pp. 535-541
Author(s):  
Shaymaa Riyadh Tahhan ◽  
Ahmad Atieh ◽  
Mehedi Hasan ◽  
Trevor Hall
Keyword(s):  
Bandpass Filter ◽  
Ring Cavity ◽  
Laser Cavity ◽  
Mode Locking ◽  
Tunable Filter ◽  
Filter Bandwidth ◽  
Active Mode ◽  
Pulse Trains ◽  
Erbium Doped ◽  
Mode Locked Laser

AbstractA simple active mode-locked erbium-doped fiber (EDF) ring laser is characterized and experimentally demonstrated. The active mode-locked laser can be tuned in the C-band wavelength range 1525 nm to 1565 nm using a tunable bandpass filter placed in the cavity. An intensity modulator placed inside the laser cavity is driven using a sinusoidal signal at different repetition rates. The laser can produce trains of pulses with a width that is controlled using the mode-locking order. The experiments demonstrated an active mode-locked laser that can generate pulse trains with 39 ns width at multiple cavity fundamental frequency of 0.67 MHz repetition rate. Numerical simulations are conducted to investigate the effect of the tunable filter bandwidth and the power of the EDF 980 nm pump on the mode-locking process and produced pulses width.

Active mode-locking of an external cavity GaInAsP laser incorporating a fibre-grating reflector

1988 ◽  
Vol 24 (23) ◽  
pp. 1439 ◽  
Author(s):  
D. Burns ◽  
D.W. Crust ◽  
J.T.K. Chang ◽  
W. Sibbett
Keyword(s):  
External Cavity ◽  
Mode Locking ◽  
Active Mode

scholarly journals Dual-band wavelength-swept active mode locking laser for multi-band fiber-optic sensors

2012 ◽  
Author(s):  
Hwi Don Lee ◽  
Chang Seok Kim ◽  
Myung Young Jeong ◽  
Zhongping Chen
Keyword(s):  
Fiber Optic ◽  
Mode Locking ◽  
Fiber Optic Sensors ◽  
Dual Band ◽  
Active Mode ◽  
Multi Band

Phase characteristics of pulses from an Nd : YAG laser with active mode locking

1997 ◽  
Vol 27 (11) ◽  
pp. 968-971
Author(s):  
A A Apolonskii ◽  
V P Drachev ◽  
Yu I Krasnikov ◽  
S V Perminov
Keyword(s):  
Mode Locking ◽  
Yag Laser ◽  
Active Mode
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