Prof. Dr. Suleiman Wadi Haroun, specializing in laser photonics from the University of Malaya in Malaysia, has participated in the discussion of the doctoral student’s dissertation by Fay Fadel Reda – Laser Applications in Electronic and Communications Engineering, the dissertation is entitled:
Tunable Free Spectral Range In Er And Yb Fiber Lasers Based On Saturable Absorbers And Filters
The discussion committee also consisted of the gentlemen whose names are listed:
1-Prof. Dr. Hussein Ali Jawad / Ph.D. of Physics / Laser /  Institute of laser for Postgraduate Studies / University of Baghdad / Chairman
2- Prof. Dr. Suleiman Wadi Haroun, specializing in laser photonics / University of Malaya in Malaysia
3-Asst. Prof. Dr.  Muhammad Karim Daher / Ph.D.-laser / laser and electro-optics/  Institute of laser for Postgraduate Studies/ University of Baghdad/ Member
4- Asst. Prof. Dr.  Hanan Jaafar/ Ph.D. Physics/ Laser/  Institute of laser for Postgraduate Studies/ University of Baghdad/ Member
5- Asst. Prof. Dr.  Taha Ahmed Aliwi / Ph.D. Optical Communications / Department of Communications Engineering / Al-Mamoun University College / Member
6- Prof. Dr. Abd al-Hadi Mutashar Abd / Ph.D. Laser Plasma / Physics /  Institute of laser  for Postgraduate Studies / University of Baghdad / Member and Supervisor
Where the aim of the study was to investigate two types of maximum phase family V2AlC and Ta2AlC as novel SAs as well as to design and fabricate three different types of filters based on MZI to generate tunable/switchable multi-length fiber lasers operating in the pulsed regime at 1 μm and 1.5 μm spectral regions using both YDFL and EDFL.
Mode locked, Q-switched operation and multiwavelength generation
have been demonstrated in erbium and ytterbium doped fiber laser cavities
using saturable absorbers (SAs) and novel filters. A novel Two high
nonlinearity 2-dimension material of max phase family which are: Vanadium
Aluminum Carbide (V2AlC) and Tantalum aluminum Carbide (Ta2AlC) were
used. They were successfully fabricated in a simple, straight, and costeffective
methods in a liquid form and freestanding polymer composite.
The fabricated SAs as well as filters were integrated separately in both
all-fiber based erbium-doped fiber laser (EDFL) / ytterbium doped fiber laser
(YDFL) ring cavities to generate a tunable/switchable multi-wavelength
operate in Q-switched and mode-locked regimes. Also, those SAs support
mode competition suppression inside the cavity and generate both
switchable/tunable operation.
Different ultra-short pulse durations of mode locked operation have been
obtained when V2AlC and Ta2AlC are sandwiched between the connector
ferrules inside both YDFL and EDFL ring cavities. As V2AlC-NF inserted in
the YDF cavity a tunable/switchable single-, dual-, triple-, quadruple
wavelengths were generated in 1 μm region with different channel spacing
operate with mode locked regime with pulse duration of about 4.9 ps and 1 ns.
Additionally, using the same YDFL cavity when Ta2AlC-NFa tunable single
wavelength emitted with tuning range from 1039.68 nm to 1065.6 nm in mode
locked regime with pulse duration of about 8.7 ps as well as up to quintuple
wavelength can be achieved. As well, up to ten- fold switchable
multiwavelength was generated in L-band operated in both dark and bright
mode locked regime as V2AlC-NF inserted inside and EDF laser cavity.
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Besides, the V2AlC /PVA modulator induces a bound state soliton operated in
mode locked regime with pulse duration of about 0.16 in the 1.5 μm band. In
addition ,a constant channel spacing with o.8 nm due to FWM was realized
in mode locked regime wit pulse width of about 17 ps. Via adjusting the
polarization controller up to seven-fold wavelength in L band with switchable
were generated from EDFL based on Ta2AlC-NF. Furthermore, A
tunable/switchable operation single-, dual-, triple-, quadruple wavelength with
SNR between 40 to 51.9 dB were realized in mode locked regime from YDFL
based Ta2AlC/PVA.
Single- and dual-wavelength operation with minimum pulse duration of
3.067 μs induced by V2AlC /PVA have been generated from the YDFL
cavity. Via adjusting the polarization controller a tunable single wavelength
tuning range from 1046.038 nm to 1063.398 nm and up to 11 wavelengths
have been obtained. When a Ta2AlC/PVA was incorporated in EDFL a Q
switched pulses with minimum pulse duration of 1.589 μs and utmost
repetition frequency of 111.4 kHz have been obtained.
In the second part of this thesis, three different filters were designed and
experimentally demonstrated based on Mach-Zehnder interferometer (MZI) as
well as a band pass filter. Different a switchable/ tunable multiwavelength
operation have been obtained with these structures. The examined SAs and the
designed and fabricated filters may find potential applications in the field of
photonics.
Among the most important recommendations of the study:
  1. V2AlC- thin film; Multiple auto-tunable/switchable wavelengths were generated in the mode-locking regime in the L and 1 μm band, in contrast to the active mode-locking. No interference of the external signal to generate the pulses allowed for shorter pulses that had a simple setting using SA.
  2. Wherein a thin piece of V2AlC-PVA was inserted inside the ring cavities of both YDFL and EDFL, a multi-wavelength tunable/switchable Q-switch with pulse duration of few microseconds and also mode-locking behavior of EDFL was achieved.
  3. FWM-assisted multi-wavelength in the 1.5 μm range with mode-locking processes was realized from EDFL based on a Ta2AlC thin film. Multiple tunable/switchable wavelengths operating in the mode-locking system were also obtained from YDFL.
  4. In the region of 1.5 μm, Ta2AlC-NPs induced a tunable multiplex laser line emission in the Q-switching regime with pulse duration of a few microseconds by Ta2AlC/PVA. Multiple tunable/switchable wavelengths operating in the mode-locking system were also obtained from YDFL.
  5. The MZI inline filter is designed and manufactured to solder a piece of high-nonlinear PCF to the YDFL cavity and insert it into the cavity of the YDFL. Through fine-tuning of the polarization control unit, it converts multiple switchable wavelengths operating in a mode-locking system.
  6. MZI single-pass filter is designed and manufactured by weld cut from pcf. Through coarse pressing on the polarization controller, multiple tunable wavelengths with different channel spacing are emitted operating in lock-mode system.
  7. A band-pass filter is designed and manufactured on the basis of a segmented MMF winding with an EDFL polarization controller. Multiple tunable/switchable wavelengths with different channel spacing were emitted depending on the strength of the BF inside the cavity triggered in the CW system.
The researcher obtained a Ph.D. with a grade of “excellence” due to her real efforts in preparing the dissertation.

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