Fabrication and Mode Identification of Compact Long-Period Gratings Written by CO$_{2}$ Laser

Chan, Hon Man; Alhassen, Fares; Tomov, I. V.; Lee, H.P.

doi:10.1109/lpt.2008.918908

Cited by 8 publications

(6 citation statements)

References 11 publications

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“…The induced index decrease has been characterized by measuring the change in phase difference by composing a Fabry-Perot interferometer [15]. Note that the index modification is non-uniform over the fiber cross section due to the laser side irradiation, which has been verified by observing the near-field profile of the coupled LP 1n modes at the resonance wavelengths for long period gratings fabricated by CO 2 -laser side irradiation [16,17]. Generally speaking, the part facing the incident direction of the CO 2 -laser experiences a larger index reduction.…”

Section: Linear Birefringence Tuningmentioning

confidence: 99%

Sensitivity enhancement of Faraday effect based heterodyning fiber laser magnetic field sensor by lowering linear birefringence

Cheng¹,

Han²,

Jin³

et al. 2013

Opt. Express

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In this paper, we demonstrate that the sensitivity of Faraday effect based heterodyning fiber laser sensors for magnetic field can be effectively enhanced by lowering the intrinsic linear birefringence inside the fiber laser cavity. Well explained by theoretical analysis and confirmed by birefringence tuning through transversal force, it shows that the sensitivity to magnetic field intensity is inversely proportional to the linear birefringence. A CO(2)-laser treatment is therefore proposed to tune the intra-cavity linear birefringence. With CO(2)-laser treatment, the intra-cavity linear birefringence can be lowered permanently to effectively enhance the sensitivity of a heterodyning fiber laser sensor to magnetic field.

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Section: Linear Birefringence Tuningmentioning

confidence: 99%

Sensitivity enhancement of Faraday effect based heterodyning fiber laser magnetic field sensor by lowering linear birefringence

Cheng¹,

Han²,

Jin³

et al. 2013

Opt. Express

View full text Add to dashboard Cite

show abstract

“…Note that the index modification is non-uniform over the fiber cross section due to the side irradiation. This has been verified by observing near-field profiles of the coupled LP 1n modes at the resonance wavelengths for long period gratings fabricated by CO 2 -laser side irradiation [22], [23]. Generally speaking, the part facing the incident direction of laser experiences a larger index reduction.…”

Section: A Beat-frequency Tuning With a Co 2 Lasermentioning

confidence: 90%

A 16-Element Multiplexed Heterodyning Fiber Grating Laser Sensor Array

Jin¹,

Liang²,

Li³

et al. 2014

J. Lightwave Technol.

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In this paper, we demonstrate the implementation of a 16-element array of heterodyning fiber grating laser sensors cascaded in a single optical fiber. Each laser consists of a Bragg grating pair inscribed in a short section of Er-doped fiber. The laser offers a RF-domain beat signal between orthogonally polarization modes and can act as a photonic sensor for the measurement of external perturbations, by monitoring the beat frequency. The laser sensors are wavelength multiplexed by inscribing fiber gratings with different pitches, and frequency multiplexed in RF domain by controlling the intracavity birefringence via CO 2 laser side irradiation. The pump power depletion as a result of mode mismatch between the active and passive fibers is a main limitation factor for the multiplexing scale. We can multiplex ten laser sensors at most with a single pump laser with an output power of 130 mW and six more sensors can be multiplexed with an additional pump laser at the other end. The measurement ability of an individual laser sensor can be affected when multiplexed in array, in terms of abrupt frequency jumps and the raised noise level. As a result, the force resolution at 1 kHz is changed from 3 to 6 nN/ √ Hz, and the minimal detectable static force is changed from 68 to 120 μN. This is attributed to the off-resonance grating couplings and the reflections at the splicing points. This effect can be weakened by selecting mode-matching fibers and optimizing grating profiles, or simply using additional optical isolators. where he founded the Institute of Photonics Technology. His current research interests include fiber-optic biochemical sensors, micro/nanofiber optical sensors, polarimetric fiber grating laser sensors, microstructured optical fiber sensors, photonic microwave generators, and photonic components for sensing and telecommunication. He has authored and coauthored more than 160 technical papers and presented more than 10 invited talks at international conferences.He is a Member of IEEE and OSA, served as the General Co-

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“…One of the main advantages of the current sensor is that in contrast with other long period fiber gratings fabricated by electric arc, CO 2 or others, this device is totally insensitive to changes in the external refractive index and has very low sensitivity to bending compared with other long period gratings where the length may be in excess of 1 cm [6,20]. In the case of LPGs fabricated by UV, the application of high temperature may erase the gratings in most cases.…”

Section: Fattened Long-period Grating Characterization and Responsementioning

confidence: 99%

High Temperature Optical Fiber Sensor Based on Compact Fattened Long-Period Fiber Gratings

Mata-Chavez

Martı́nez-Rios

Estudillo-Ayala

et al. 2013

Sensors

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A compact high temperature fiber sensor where the sensor head consists of a short fattened long period fiber grating (F-LPFG) of at least 2 mm in length and background loss of −5 dBm is reported. On purpose two different F-LPFGs were used to measure temperature variations, taking advantage of their broad spectrum and the slope characteristics of the erbium light source. This approach affected the spectrum gain as the linear band shifting took place. The measured sensitivity of the long period fiber gratings were about 72 pm/°C in a range from 25 to 500 °C. Here, the temperature rate of the experiment was 0.17 °C/s and the temperature response time was within 3 s. Moreover, temperature changes were detected with an InGaAs photodetector, where a sensitivity of 0.05 mV/°C was achieved.

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Fabrication and Mode Identification of Compact Long-Period Gratings Written by CO$_{2}$ Laser

Cited by 8 publications

References 11 publications

Sensitivity enhancement of Faraday effect based heterodyning fiber laser magnetic field sensor by lowering linear birefringence

Sensitivity enhancement of Faraday effect based heterodyning fiber laser magnetic field sensor by lowering linear birefringence

A 16-Element Multiplexed Heterodyning Fiber Grating Laser Sensor Array

High Temperature Optical Fiber Sensor Based on Compact Fattened Long-Period Fiber Gratings

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