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Multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency spacing

Shee YG, Al-Mansoori MH, Ismail A, Hitam S, Mahdi MA

Opt Express, 2011 Jan 31;19(3):1699-706.
PMID: 21368983 DOI: 10.1364/OE.19.001699

We demonstrate a multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency spacing. The wider channel spacing is realized by circulating the odd-order Stokes signals in the Brillouin gain medium through a four-port circulator. The circulated odd-order Stokes signals are amplified by the Brillouin gain and thus produce even-order Stokes signals at the output. These signals are then amplified by erbium gain block to form a ring-cavity laser. Ten channels with 0.174 nm spacing that are generated at 0.5 mW Brillouin pump power and 150 mW pump power at 1480 nm can be tuned from 1556 nm to 1564 nm. The minimum optical signal-to-noise ratio of the generated output channels is 30 dB with maximum power fluctuations of ±0.5 dB.
Seamless tuning range based-on available gain bandwidth in multiwavelength Brillouin fiber laser

Ajiya M, Mahdi MA, Al-Mansoori MH, Hitam S, Mokhtar M

Opt Express, 2009 Apr 13;17(8):5944-52.
PMID: 19365413

We experimentally demonstrate a simple widely tunable multiwavelength Brillouin/Erbium fiber laser that can be tuned over the entire C-band, thereby greatly improving the tuning range limitation faced by the previous Brillouin-erbium fiber laser architectures. Tuning range of 39 nm from 1527 nm to 1566 nm, which is only limited by the amplification bandwidth of the erbium gain was successfully achieved. At Brillouin pump wavelength of 1550 nm and 1480 nm laser pump and Brillouin pump powers of 130 mW and 2 mW respectively, all the generated output channels have peak power above 0 dBm, with the first output channel having a peak power of 8.52 dBm. The experimental set up that consists of only 4 optical components, is simple, devoid of the complex structure employed previously to enhance the tunability and feedback mechanism normally associated with multiwavelength Brillouin-erbium fiber laser sources. The generated output channels are stable, rigidly separated by 10 GHz (0.08 nm).
An Unusual Presentation of Midline Lethal Granuloma

Chin EW, Saniasiaya J, Hitam S, Hassan E, Kah Wai N

Indian J Otolaryngol Head Neck Surg, 2024 Apr;76(2):2137-2140.
PMID: 38566723 DOI: 10.1007/s12070-023-04466-x

Extranodal natural killer T-cell lymphoma, nasal type (ENKTCL), is a rare form of non-Hodgkin lymphoma that is strongly related to Epstein-Barr Virus (EBV) infection and commonly presents as "midline lethal granuloma." Herein, we report a middle-aged lady who presented with a two-week history of fever, sore throat and constitutional symptoms. Intraoral examination revealed a lacerated soft palate with an ulcerated uvula. A diagnosis of ENKTCL was confirmed through deep biopsies under general anaesthesia supplemented with a positive serum EBV genome. Unfortunately, she succumbed due to disease progression with left frontal brain metastasis with concurrent pulmonary tuberculosis before treatment was completed. The recommended treatment is multimodality with L-asparaginase-containing regimes chemotherapy in an advanced stage, relapsed, or refractory ENKTCL for better outcomes. The quantification of circulating plasma EBV deoxyribonucleic acid (DNA) is helpful as the baseline of tumour load and a biomarker for monitoring treatment response and prognostication. We advocate repeated and deeper core tissue biopsies.
Fulltext Diagnostic Dilemma: Tuberculosis Mastoiditis in an Immunocompromised Patient

Tiong SL, Aida WN, I R, Hitam S

Cureus, 2024 Jul;16(7):e65797.
PMID: 39219903 DOI: 10.7759/cureus.65797

Tuberculosis (TB) is endemic in Malaysia but rarely affects the middle ear cleft. Common presentations of TB mastoiditis include unilateral, painless otorrhea, multiple small perforations of the tympanic membrane, and facial nerve palsy, although these symptoms can vary among patients. The diagnosis of TB mastoiditis is challenging due to its rarity and its similar presentation to common bacterial ear infections. This often leads to missed diagnoses, resulting in significant delays in treatment and potential complications. CT scans and histopathological examinations are crucial for diagnosing TB mastoiditis. Real-time polymerase chain reaction offers higher sensitivity and specificity compared to conventional methods for detecting Mycobacterium tuberculosis. TB infection should be considered in cases of otitis media that do not respond well to empirical antibiotic therapy. It is essential to send appropriate samples for TB testing to ensure timely diagnosis and treatment. This case report highlights the diagnostic challenges and complications encountered in a 22-year-old immunocompromised woman with TB mastoiditis.
Multiwavelength Brillouin fiber laser with enhanced reverse-S-shaped feedback coupling assisted by out-of-cavity optical amplifier

Rahman ZA, Hitam S, Al-Mansoori MH, Abas AF, Mahdi MA

Opt Express, 2011 Oct 24;19(22):21238-45.
PMID: 22108976 DOI: 10.1364/OE.19.021238

A multiwavelength widely tunable Brillouin optical comb with an enhanced reverse-S-shaped feedback coupling assisted by out-of-cavity optical amplifier is demonstrated. The enhancement is done by locating the amplifier and the Brillouin pump into the reverse-S-shaped fiber section. The oscillating modes in the cavity are directly influenced solely by the Brillouin gain. A wide tuning range of 45 nm is obtained that is only limited by the erbium amplification bandwidth. An average of eleven laser lines that can be tuned to over 45 nm wavelengths is obtained at 40% optimum output coupling ratio.
Particle swarm optimization on threshold exponential gain of stimulated Brillouin scattering in single mode fibers

Al-Asadi HA, Al-Mansoori MH, Hitam S, Saripan MI, Mahdi MA

Opt Express, 2011 Jan 31;19(3):1842-53.
PMID: 21368999 DOI: 10.1364/OE.19.001842

We implement a particle swarm optimization (PSO) algorithm to characterize stimulated Brillouin scattering phenomena in optical fibers. The explicit and strong dependence of the threshold exponential gain on the numerical aperture, the pump laser wavelength and the optical loss coefficient are presented. The proposed PSO model is also evaluated with the localized, nonfluctuating source model and the distributed (non-localized) fluctuating source model. Using our model, for fiber lengths from 1 km to 29 km, the calculated threshold exponential gain of stimulated Brillouin scattering is gradually decreased from 17.4 to 14.6 respectively. The theoretical results of Brillouin threshold power predicted by the proposed PSO model show a good agreement with the experimental results for different fiber lengths from 1 km to 12 km.
All-optical generation of a 21 GHz microwave carrier by incorporating a double-Brillouin frequency shifter

Shee YG, Mahdi MA, Al-Mansoori MH, Yaakob S, Mohamed R, Zamzuri AK, et al.

Opt Lett, 2010 May 1;35(9):1461-3.
PMID: 20436603 DOI: 10.1364/OL.35.001461

An all-optical generation of a microwave carrier at 21 GHz that incorporates a double-Brillouin frequency shifter is presented. The frequency shift of approximately 21 GHz is achieved by generating the second-order Brillouin Stokes signal from the Brillouin pump. This is accomplished through the circulation and isolation of its first-order Stokes signal in the optical fiber. The Brillouin pump signal is heterodyned with its second-order Brillouin Stokes signal at a high-speed photodetector, and the output beating frequency is equal to the offset between these two signals. The generated microwave carrier is measured at 21.3968 GHz, and the carrier phase noise as low as -58.67 dBc/Hz is achieved.
Effects of pump recycling technique on stimulated Brillouin scattering threshold: a theoretical model

Al-Asadi HA, Al-Mansoori MH, Ajiya M, Hitam S, Saripan MI, Mahdi MA

Opt Express, 2010 Oct 11;18(21):22339-47.
PMID: 20941134 DOI: 10.1364/OE.18.022339

We develop a theoretical model that can be used to predict stimulated Brillouin scattering (SBS) threshold in optical fibers that arises through the effect of Brillouin pump recycling technique. Obtained simulation results from our model are in close agreement with our experimental results. The developed model utilizes single mode optical fiber of different lengths as the Brillouin gain media. For 5-km long single mode fiber, the calculated threshold power for SBS is about 16 mW for conventional technique. This value is reduced to about 8 mW when the residual Brillouin pump is recycled at the end of the fiber. The decrement of SBS threshold is due to longer interaction lengths between Brillouin pump and Stokes wave.
Double Brillouin frequency shift through circulation of odd-order Stokes signal

Shee YG, Al-Mansoori MH, Ismail A, Hitam S, Mahdi MA

Appl Opt, 2010 Jul 10;49(20):3956-9.
PMID: 20648173 DOI: 10.1364/AO.49.003956

We demonstrate a simple configuration for generating a double Brillouin frequency shift through the circulation of an odd-order Brillouin Stokes signal. It is operated based on cascaded Brillouin scattering in single-mode optical fibers that behave as the Brillouin gain media. A four-port circulator is incorporated into the setup to circulate the odd-order Brillouin Stokes signal in the fiber. It thus initiates a higher order Brillouin Stokes signal, which is double Brillouin frequency downshifted from the input signal. For the 5 km long fiber, the Brillouin pump power at 23 mW gives a clean output spectrum with 30 dB sideband suppression ratio. The output signal is 0.174 nm or approximately 21.7 GHz downshifted from the input signal.
Fulltext Large Vallecula Epiglottica Lipoma: A Rare but Fatal Cause of Dysphagia

Sharudin SN, Thangavelu T, Roslim SN, Hitam S, Mat Baki M

Cureus, 2022 Oct;14(10):e30250.
PMID: 36381797 DOI: 10.7759/cureus.30250

Lipoma is a benign mesenchymal tumor with 13% occurrence in the head and neck region. Despite being the commonest type of tumor, it only accounts for 0.6% of the upper aerodigestive tract. We report a case of a 41-year-old gentleman who presented with progressively worsening dysphagia and a muffled voice. A flexible nasopharyngeal endoscope showed a solitary well-lobulated pedunculated cystic-looking mass occupying the oropharynx arising from the vallecular space and lingual surface of the epiglottis with a partially seen mobile posterior vocal cord. CT of the neck showed a single lesion with fat attenuation in the right vallecula and right lateral lingual epiglottis. The patient underwent endoscopic surgical excision and fully recovered post-operatively. Although rare, lipoma must be considered one of the differential diagnoses of midline laryngeal mass. Therefore, prompt excision needs to be performed to prevent a catastrophic outcome.
Fulltext Primary Extraosseous Ewing Sarcoma of the Maxillary Sinus in an Adult-A Rare Case Report

Chin EW, Abu-Bakar AZ, Hitam S, Kah-Wai N, Abdullah MA

Iran J Otorhinolaryngol, 2019 Nov;31(107):391-397.
PMID: 31857985 DOI: 10.22038/ijorl.2019.35555.2173

INTRODUCTION: Ewing sarcoma (ES), which is described as diffuse endothelioma of the bone, is divided into osseous and extraosseous Ewing sarcoma (EES) mostly affecting children and adolescents. It is a rare, aggressive, and poorly differentiated small blue round cell tumor that seldom affects the head and neck regions.
CASE REPORT: Herein, we reported a 46-year-old man presenting with right nasal block, epistaxis, and epiphora from the right eye for one month. The nasal endoscopy revealed a friable mass arising from the anterior half of the right nasal cavity. Histological findings were suggestive of Ewing sarcoma. A contrast-enhanced computed tomography (CT) scan of the paranasal sinuses showed a soft tissue mass in the right anterior nasal cavity with mucosal thickening in the right maxillary sinus, without any bony erosion or distant metastasis. The patient underwent endoscopic medial maxillectomy with modified Denker's procedure, followed by a 6-cycle course of chemotherapy. He was clinically well after chemotherapy; however, the recent bone scans were suggestive of bone involvement with the tumor.
CONCLUSION: The EES of paranasal sinus in the head and neck regions is extremely rare and requires exceptional attention due to their adjacent vital structures. The ES diagnosis-related dilemma arises from the numerous differential diagnoses of small round blue cell tumors. In this regard, accurate diagnosis is important, since ES requires a multi-modality approach. Furthermore, early diagnosis and aggressive intervention are crucial to obtain good prognosis and function.
Lymphoma with superimposed tuberculosis and fungal infection mimicking parapharyngeal abscess complicated with recurrent neurocardiogenic syncope: a case report

Sharudin SN, Huda Al Firdas AN, Hitam S, Hamid Z, Nordin NJ, Othman N, et al.

Malays J Pathol, 2020 Aug;42(2):287-291.
PMID: 32860384

INTRODUCTION: Lymphoma of parapharyngeal space (PPS) is a rare condition. The clinical presentations may vary and often masquerades as infection or an inflammatory condition. A misdiagnosis will lead to a delay in treatment of the disease. Due to the complex anatomy of PPS, any attributed pressure from masses can lead to a life-threatening event such as cardiac syncope.
CASE REPORT: We report a rare case of PPS B-cell non-Hodgkin lymphoma with superimposed Tuberculosis (TB) and fungal infection that presents with several episodes of syncope and hemodynamic depression.
DISCUSSION: The clinical entities in PPS lesions syncope and its associated syndromes, pathophysiology, and differential diagnosis together with possible managements are further discussed.
A Case Report on Cervicofacial Subcutaneous Emphysema and Its Management: A Unique Presentation of Congenital Defect of the Foramen of Huschke

Sharudin SN, Salahuddin NA, Md Arepen SA, Md Anuar NA, Hassan NE, Hitam S, et al.

Cureus, 2023 Oct;15(10):e47078.
PMID: 38021523 DOI: 10.7759/cureus.47078

Congenital defect to the foramen of Huschke with a manifestation as temporomandibular joint (TMJ) soft tissue herniation in a radiological study is rare. The patient may present with nonspecific symptoms such as otalgia, mandibular joint pain, tinnitus and conductive hearing loss, and scarcely cervicofacial subcutaneous emphysema. Here, we report a patient presented with cervicofacial subcutaneous emphysema secondary to a congenital defect of the foramen of Huschke. A 45-year-old gentleman presented with right-sided neck swelling and right otalgia with a crackling sound over the right ear upon chewing. Examination shows right-sided fullness with subcutaneous emphysema from the zygoma to the upper neck. Otherwise, it is non-tender with no skin changes, and the facial nerve is intact. Otoendoscopy shows erythematous soft tissue bulging of the anterior wall of the right external auditory canal (EAC) upon closing the mouth and prolapsing upon mouth opening. The right tympanic membrane was intact. Contrast-enhanced computer tomography (CECT) of the neck and temporal region revealed extensive cervicofacial subcutaneous emphysema with a bony defect at the anterior wall of the right EAC, indicating fistulous communication between the right EAC and TMJ. The subcutaneous emphysema resolved on the treatment of the right otitis externa. The patient is subjected to a combined approach of open and endoscopic-assisted repair of the anterior EAC wall defect. TMJ herniation into the anterior EAC is rare; however, the patient presentation may vary. CECT is the gold standard for diagnosing and facilitating treatment options. Treatment choice is based on the patient's condition, including conservative or surgical intervention.