We design As 2 Se 3 and As 2 S 3 chalcogenide photonic nanowires to optimize the soliton self-com... more We design As 2 Se 3 and As 2 S 3 chalcogenide photonic nanowires to optimize the soliton self-compression with short distances and ultralow input pulse energy. We numerically demonstrate the generation of single optical cycle in an As 2 S 3 photonic nanowire: a 5.07 fs compressed pulse is obtained starting from 250 fs input pulse with 50 pJ in 0.84 mm-long As 2 S 3 nanowire. Taking into account the high two photon absorption (TPA) coefficient in the As 2 Se 3 glass, accurate modeling shows the compression of 250 fs down to 25.4 fs in 2.1 mm-long nanowire and with 10 pJ input pulse energy.
Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, an... more Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks.
A novel methodology for precisely determining the eigenaxes and effective twist of a solid-core p... more A novel methodology for precisely determining the eigenaxes and effective twist of a solid-core polarisation maintaining fibre with a slightly elliptical effective core in an experimental setup with an ultrashort pulse laser is presented. This geometrical identification relies on experimental modal analysis and by utilising an incoherent ultrashort optical pulse fragment measurement and modelling procedure, and is a prerequisite for precise measurements and characterisation of this class of fibres. This orienting method is applied in the study of low threshold and temporally and polarisation stable supercontinuum generation in ~2m length of photonic crystal fibre, utilizing a modelocked Ti:Sapphire laser.
Http Dx Doi Org 10 1080 09500340 2014 880523, Jan 20, 2014
ABSTRACT We propose a modified Mach–Zehnder interferometer design based on elliptical silica phot... more ABSTRACT We propose a modified Mach–Zehnder interferometer design based on elliptical silica photonic nanowires. The use of the interferometer as an evanescent field-based refractive index (RI) sensor was numerically investigated. Single-mode operation, maintaining polarization and very high sensitivity, is achieved at short optical wavelengths by simply using elliptical nanowires. The proposed sensor is capable of determining the RI of benzene solutions with different concentrations in water and detecting a RI variation of the order of 10−6 RI units in only a 1-mm length sensitive area. Extremely high sensitivity of 4.63 rad/μm is achieved using an 800 nm elliptical silica nanowire diameter. The operating wavelengths (λ = 650 nm and 970 nm) were chosen to avoid high water absorption. The sensor is shown to be an alternative solution to small circular-nanowire-based sensor whose core size needs to be significantly reduced below 400 nm to achieve comparable performance.
2004 IEEE International Conference on Industrial Technology, 2004. IEEE ICIT '04., 2004
... ASE is approximated by: QASE (r)=g 4 (gm(r)-l )nSp(r,vm)A vm (9) m=l where nip is spontaneous... more ... ASE is approximated by: QASE (r)=g 4 (gm(r)-l )nSp(r,vm)A vm (9) m=l where nip is spontaneous emission factor expressed by: ... Indeed, fR increases when the polarization current /p increases and also when the volume of the active layer decreases. ...
We characterize the nonlinear propagation of ultra-short femtosecond pulses in a highly nonlinear... more We characterize the nonlinear propagation of ultra-short femtosecond pulses in a highly nonlinear As 2 Se 3 -based chalcogenide photonic crystal fiber (PCF). We propose an accurate fit of the Raman response function of the As 2 Se 3 chalcogenide glass in order to evaluate the effect of the stimulated Raman scattering on the supercontinuum (SC) generation in the PCF. We have investigated the interplay of the nonlinear effects leading to the SC generation as a function of the input power and the fiber length. The SC spanning from 1.9 µm to 4 µm was generated in 1-cm fiber length with 200 fs pulses at an input average power of 500 µW. The generation of the SC has mainly been attributed to the Raman effect which is responsible for the solitonic fission and the dispersive wave radiation.
We report on numerical and experimental studies of supercontinuum (SC) gen-eration in a silica-ba... more We report on numerical and experimental studies of supercontinuum (SC) gen-eration in a silica-based nonlinear polarization-maintaining photonic crystal fiber (PM-PCF). The optical properties of the fundamental mode of the PM-PCF were numerically determined in terms of birefringence, chromatic dispersion and nonlinear coefficient. The fiber has an air hole diameter of 0.6 µm and a pitch of 1.25 µm exhibiting a nonlinear coefficient of 90 km −1 W −1 and a high value of birefringence which we found to be equal to 4 · 10 −4 at λ = 820 nm. We also determined the positions of the slow and fast axes of the PM-PCF according to the laboratory frame, using two different techniques based on near and far fields. The SC was generated by coupling ultra-short pulses delivered by a mode-locked femtosecond Ti: Sapphire laser centered at 820 nm with a repetition rate of 202 MHz at the average power of 20 mW and having duration of 56 fs. The generation of over 800 nm bandwidth of visible and infrared...
ABSTRACT Stimulated Brillouin scattering (SBS) performances of small core tellurite photonic crys... more ABSTRACT Stimulated Brillouin scattering (SBS) performances of small core tellurite photonic crystal fibers (PCF) are rigorously studied. We propose a design of tellurite PCF that is used for slow-light-based applications. We developed a two-dimensional finite element mode solver to numerically study the acoustic and optical properties of complex refractive index profiles including tellurite PCF. Our results include the calculation of Brillouin gain spectrum, Brillouin gain coefficient (gB) and Brillouin frequency shift by taking into account the contribution of the higher-order acoustic modes. Several simulations were run by varying the air-filling ratio of various PCF structures to enhance the SBS. The real scanning electron microscope image of a small core of highly nonlinear tellurite fiber is considered. Optimized results show a frequency shift of 8.43 GHz and a Brillouin gain of 9.48×10−11 m/W with a time delay between 21 and 140 ns. Such fibers have drawn much interest because of their capacity for increasing and tailoring the SBS gain.
Applications exploiting the mode confinement properties in specialty fibers take advantage of the... more Applications exploiting the mode confinement properties in specialty fibers take advantage of the extremely high intensity achieved in the minimum waist region yielding to high nonlinearities and supercontinuum (SC) generation. In fact, the generation of "white light" coined a supercontinuum, presents the result of the collection of nonlinear optical effects yielding remarkable spectral broadening of the original pump signal. By properly selecting the geometry and the material composition, the generation of broadband coherent SC from blue to mid-IR wavelengths regions is demonstrated in different highly nonlinear waveguides with low input pulse energy and in short fiber lengths.
Frontiers in Optics 2012/Laser Science XXVIII, 2012
ABSTRACT We present a investigation on Stimulated Brillouin scattering (SBS) in three-core tellur... more ABSTRACT We present a investigation on Stimulated Brillouin scattering (SBS) in three-core tellurite microstructured optical fiber (MOF). The results show that the SBS in this fiber is much stronger than that in the single-core tellurite MOF.
We report the results of a numerical and experimental analysis of femtosecond pulse propagation i... more We report the results of a numerical and experimental analysis of femtosecond pulse propagation in a highly nonlinear photonic crystal fibre (PCF). The propagation of ultrashort pulses in PCF is studied taking into account the effects of dispersion, self-phase ...
Small core As 2 Se 3 -based photonic crystal fibers (PCFs) are accurately characterized for compa... more Small core As 2 Se 3 -based photonic crystal fibers (PCFs) are accurately characterized for compact, high power, ultrabroadband, and coherent supercontinuum generation within few millimeters fiber length. Bandwidths of ∼5.3 m, 5 m, and 3.2 m were calculated for hole-to-hole spacings Λ = 3.5 m, 4.5 m, and 5.5 m, respectively. The spectral broadening in the chalcogenide PCF is mainly caused by self-phase modulation and Raman-induced soliton self-frequency shift. The results show that small core As 2 Se 3 PCFs are a promising candidate for mid-IR SCG up to ∼8 m.
2008 10th Anniversary International Conference on Transparent Optical Networks, 2008
To provide contention resolution and QoS management while allowing controllable delaying of optic... more To provide contention resolution and QoS management while allowing controllable delaying of optical traffics, we effectively designed a node architecture suitable for optical packet and burst switching. The proposed architecture is based on a set of novel traffic engineering protocols providing QoS guarantees and allowing burst transmission, admission control, contention resolution, and real-time congestion control. The architecture also includes the
ABSTRACT This work provides a new type of mid-infrared supercontinuum (SC) source with flat shape... more ABSTRACT This work provides a new type of mid-infrared supercontinuum (SC) source with flat shape, broadband and excellent coherence properties by using aperiodic nanofiber with all normal dispersion. We describe in detail a new procedure of maximizing the bandwidth of mid-infrared supercontinuum in highly nonlinear As2Se3 aperiodic nanofiber. Our simulation results show a SC extending from 1795 to 6525 nm in only 8 mm-length of As2Se3 -based small core nanofiber with low input energy E=100 pJ.
ABSTRACT An equiangular spiral (ES) photonic crystal fiber (PCF) design in tellurite glass has be... more ABSTRACT An equiangular spiral (ES) photonic crystal fiber (PCF) design in tellurite glass has been presented. The structure parameters have been tailored for zero dispersion wavelength (ZDW) at λZDW=1570 nm. The fiber structure has high nonlinearity (γ = 2000 w-1 Km-1) at 1550 nm wavelength with very low and flat dispersion -0.152 [ps/(nm×km)]. We have generated supercontinuum using only 2 mm length of tellurite ES PCF with low input pulse energy of 200 pJ by pumping at 1550 nm. The proposed fiber may be a suitable candidate for nonlinear applications.
ABSTRACT A new design of the As2Se3 microfiber has been presented. With the optimized geometric p... more ABSTRACT A new design of the As2Se3 microfiber has been presented. With the optimized geometric parameters: pitch Λ= 0.8 μm and five different air filling ratios varying from 0.4 to 0.95, the structure exhibits an all normal dispersion with a flat top equal to -2.3 [ps/(nm.km)], a confinement loss less than 10-2 dB/km, and a large nonlinear coefficient equal to 7250 (w. km)-1. Using the generalized nonlinear Schrödinger equation, we generate a very broadband supercontinuum (SC) in the mid-infrared region. By pumping the fiber at λp=5.24 μm with a femtosecond laser having 50 fs as a width with a relatively low energy of E=80 pJ, we generate a large spectrum extending from 2 μm to 10 μm in only 2 mm fiber length. The generated SC demonstrates perfect coherence property over the entire bandwidth. SC generation extended into the mid-infrared (IR) spectral region have potential usefulness in a variety of applications requiring a broad mid-IR spectrum such as fiber sensing, IR spectroscopy, fiber laser, optical tomography coherence.
We design As 2 Se 3 and As 2 S 3 chalcogenide photonic nanowires to optimize the soliton self-com... more We design As 2 Se 3 and As 2 S 3 chalcogenide photonic nanowires to optimize the soliton self-compression with short distances and ultralow input pulse energy. We numerically demonstrate the generation of single optical cycle in an As 2 S 3 photonic nanowire: a 5.07 fs compressed pulse is obtained starting from 250 fs input pulse with 50 pJ in 0.84 mm-long As 2 S 3 nanowire. Taking into account the high two photon absorption (TPA) coefficient in the As 2 Se 3 glass, accurate modeling shows the compression of 250 fs down to 25.4 fs in 2.1 mm-long nanowire and with 10 pJ input pulse energy.
Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, an... more Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks.
A novel methodology for precisely determining the eigenaxes and effective twist of a solid-core p... more A novel methodology for precisely determining the eigenaxes and effective twist of a solid-core polarisation maintaining fibre with a slightly elliptical effective core in an experimental setup with an ultrashort pulse laser is presented. This geometrical identification relies on experimental modal analysis and by utilising an incoherent ultrashort optical pulse fragment measurement and modelling procedure, and is a prerequisite for precise measurements and characterisation of this class of fibres. This orienting method is applied in the study of low threshold and temporally and polarisation stable supercontinuum generation in ~2m length of photonic crystal fibre, utilizing a modelocked Ti:Sapphire laser.
Http Dx Doi Org 10 1080 09500340 2014 880523, Jan 20, 2014
ABSTRACT We propose a modified Mach–Zehnder interferometer design based on elliptical silica phot... more ABSTRACT We propose a modified Mach–Zehnder interferometer design based on elliptical silica photonic nanowires. The use of the interferometer as an evanescent field-based refractive index (RI) sensor was numerically investigated. Single-mode operation, maintaining polarization and very high sensitivity, is achieved at short optical wavelengths by simply using elliptical nanowires. The proposed sensor is capable of determining the RI of benzene solutions with different concentrations in water and detecting a RI variation of the order of 10−6 RI units in only a 1-mm length sensitive area. Extremely high sensitivity of 4.63 rad/μm is achieved using an 800 nm elliptical silica nanowire diameter. The operating wavelengths (λ = 650 nm and 970 nm) were chosen to avoid high water absorption. The sensor is shown to be an alternative solution to small circular-nanowire-based sensor whose core size needs to be significantly reduced below 400 nm to achieve comparable performance.
2004 IEEE International Conference on Industrial Technology, 2004. IEEE ICIT '04., 2004
... ASE is approximated by: QASE (r)=g 4 (gm(r)-l )nSp(r,vm)A vm (9) m=l where nip is spontaneous... more ... ASE is approximated by: QASE (r)=g 4 (gm(r)-l )nSp(r,vm)A vm (9) m=l where nip is spontaneous emission factor expressed by: ... Indeed, fR increases when the polarization current /p increases and also when the volume of the active layer decreases. ...
We characterize the nonlinear propagation of ultra-short femtosecond pulses in a highly nonlinear... more We characterize the nonlinear propagation of ultra-short femtosecond pulses in a highly nonlinear As 2 Se 3 -based chalcogenide photonic crystal fiber (PCF). We propose an accurate fit of the Raman response function of the As 2 Se 3 chalcogenide glass in order to evaluate the effect of the stimulated Raman scattering on the supercontinuum (SC) generation in the PCF. We have investigated the interplay of the nonlinear effects leading to the SC generation as a function of the input power and the fiber length. The SC spanning from 1.9 µm to 4 µm was generated in 1-cm fiber length with 200 fs pulses at an input average power of 500 µW. The generation of the SC has mainly been attributed to the Raman effect which is responsible for the solitonic fission and the dispersive wave radiation.
We report on numerical and experimental studies of supercontinuum (SC) gen-eration in a silica-ba... more We report on numerical and experimental studies of supercontinuum (SC) gen-eration in a silica-based nonlinear polarization-maintaining photonic crystal fiber (PM-PCF). The optical properties of the fundamental mode of the PM-PCF were numerically determined in terms of birefringence, chromatic dispersion and nonlinear coefficient. The fiber has an air hole diameter of 0.6 µm and a pitch of 1.25 µm exhibiting a nonlinear coefficient of 90 km −1 W −1 and a high value of birefringence which we found to be equal to 4 · 10 −4 at λ = 820 nm. We also determined the positions of the slow and fast axes of the PM-PCF according to the laboratory frame, using two different techniques based on near and far fields. The SC was generated by coupling ultra-short pulses delivered by a mode-locked femtosecond Ti: Sapphire laser centered at 820 nm with a repetition rate of 202 MHz at the average power of 20 mW and having duration of 56 fs. The generation of over 800 nm bandwidth of visible and infrared...
ABSTRACT Stimulated Brillouin scattering (SBS) performances of small core tellurite photonic crys... more ABSTRACT Stimulated Brillouin scattering (SBS) performances of small core tellurite photonic crystal fibers (PCF) are rigorously studied. We propose a design of tellurite PCF that is used for slow-light-based applications. We developed a two-dimensional finite element mode solver to numerically study the acoustic and optical properties of complex refractive index profiles including tellurite PCF. Our results include the calculation of Brillouin gain spectrum, Brillouin gain coefficient (gB) and Brillouin frequency shift by taking into account the contribution of the higher-order acoustic modes. Several simulations were run by varying the air-filling ratio of various PCF structures to enhance the SBS. The real scanning electron microscope image of a small core of highly nonlinear tellurite fiber is considered. Optimized results show a frequency shift of 8.43 GHz and a Brillouin gain of 9.48×10−11 m/W with a time delay between 21 and 140 ns. Such fibers have drawn much interest because of their capacity for increasing and tailoring the SBS gain.
Applications exploiting the mode confinement properties in specialty fibers take advantage of the... more Applications exploiting the mode confinement properties in specialty fibers take advantage of the extremely high intensity achieved in the minimum waist region yielding to high nonlinearities and supercontinuum (SC) generation. In fact, the generation of "white light" coined a supercontinuum, presents the result of the collection of nonlinear optical effects yielding remarkable spectral broadening of the original pump signal. By properly selecting the geometry and the material composition, the generation of broadband coherent SC from blue to mid-IR wavelengths regions is demonstrated in different highly nonlinear waveguides with low input pulse energy and in short fiber lengths.
Frontiers in Optics 2012/Laser Science XXVIII, 2012
ABSTRACT We present a investigation on Stimulated Brillouin scattering (SBS) in three-core tellur... more ABSTRACT We present a investigation on Stimulated Brillouin scattering (SBS) in three-core tellurite microstructured optical fiber (MOF). The results show that the SBS in this fiber is much stronger than that in the single-core tellurite MOF.
We report the results of a numerical and experimental analysis of femtosecond pulse propagation i... more We report the results of a numerical and experimental analysis of femtosecond pulse propagation in a highly nonlinear photonic crystal fibre (PCF). The propagation of ultrashort pulses in PCF is studied taking into account the effects of dispersion, self-phase ...
Small core As 2 Se 3 -based photonic crystal fibers (PCFs) are accurately characterized for compa... more Small core As 2 Se 3 -based photonic crystal fibers (PCFs) are accurately characterized for compact, high power, ultrabroadband, and coherent supercontinuum generation within few millimeters fiber length. Bandwidths of ∼5.3 m, 5 m, and 3.2 m were calculated for hole-to-hole spacings Λ = 3.5 m, 4.5 m, and 5.5 m, respectively. The spectral broadening in the chalcogenide PCF is mainly caused by self-phase modulation and Raman-induced soliton self-frequency shift. The results show that small core As 2 Se 3 PCFs are a promising candidate for mid-IR SCG up to ∼8 m.
2008 10th Anniversary International Conference on Transparent Optical Networks, 2008
To provide contention resolution and QoS management while allowing controllable delaying of optic... more To provide contention resolution and QoS management while allowing controllable delaying of optical traffics, we effectively designed a node architecture suitable for optical packet and burst switching. The proposed architecture is based on a set of novel traffic engineering protocols providing QoS guarantees and allowing burst transmission, admission control, contention resolution, and real-time congestion control. The architecture also includes the
ABSTRACT This work provides a new type of mid-infrared supercontinuum (SC) source with flat shape... more ABSTRACT This work provides a new type of mid-infrared supercontinuum (SC) source with flat shape, broadband and excellent coherence properties by using aperiodic nanofiber with all normal dispersion. We describe in detail a new procedure of maximizing the bandwidth of mid-infrared supercontinuum in highly nonlinear As2Se3 aperiodic nanofiber. Our simulation results show a SC extending from 1795 to 6525 nm in only 8 mm-length of As2Se3 -based small core nanofiber with low input energy E=100 pJ.
ABSTRACT An equiangular spiral (ES) photonic crystal fiber (PCF) design in tellurite glass has be... more ABSTRACT An equiangular spiral (ES) photonic crystal fiber (PCF) design in tellurite glass has been presented. The structure parameters have been tailored for zero dispersion wavelength (ZDW) at λZDW=1570 nm. The fiber structure has high nonlinearity (γ = 2000 w-1 Km-1) at 1550 nm wavelength with very low and flat dispersion -0.152 [ps/(nm×km)]. We have generated supercontinuum using only 2 mm length of tellurite ES PCF with low input pulse energy of 200 pJ by pumping at 1550 nm. The proposed fiber may be a suitable candidate for nonlinear applications.
ABSTRACT A new design of the As2Se3 microfiber has been presented. With the optimized geometric p... more ABSTRACT A new design of the As2Se3 microfiber has been presented. With the optimized geometric parameters: pitch Λ= 0.8 μm and five different air filling ratios varying from 0.4 to 0.95, the structure exhibits an all normal dispersion with a flat top equal to -2.3 [ps/(nm.km)], a confinement loss less than 10-2 dB/km, and a large nonlinear coefficient equal to 7250 (w. km)-1. Using the generalized nonlinear Schrödinger equation, we generate a very broadband supercontinuum (SC) in the mid-infrared region. By pumping the fiber at λp=5.24 μm with a femtosecond laser having 50 fs as a width with a relatively low energy of E=80 pJ, we generate a large spectrum extending from 2 μm to 10 μm in only 2 mm fiber length. The generated SC demonstrates perfect coherence property over the entire bandwidth. SC generation extended into the mid-infrared (IR) spectral region have potential usefulness in a variety of applications requiring a broad mid-IR spectrum such as fiber sensing, IR spectroscopy, fiber laser, optical tomography coherence.
Uploads
Papers by Mourad Zghal