Browsing by Author "Hamid, R."
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Item Open Access 33-fs Yb-fiber laser comb locked to Cs-atomic clock(IEEE, 2013) Şenel, Çağrı; Hamid, R.; Erdoğan, C.; Çelik, M.; Kara, O.; İlday, Fatih ÖmerDespite the prevalence of fiber frequency combs around 1.5 μm, few fully stabilized frequency combs have been demonstrated around 1.0 μm, despite the generally superior performance of Yb-fiber lasers compared to Er-fiber lasers. Short pulses are to generate coherent supercontinuum using anomalous dispersion regime of microstructured fibers. Near-zero cavity dispersion is highly desirable for low-noise frequency comb performance. Here, we report a Yb-doped fiber laser that operates at net-zero group-velocity dispersion and produces pulses that can be compressed externally to 33-fs. The frequency comb generated by this system is repetition-and carrier-envelope-phase-locked to Cs atomic clocks. The laser oscillator design is based on a novel algorithmic methodology, which allows us to design cavities to meet specific requirements; in this case, there was the need to generate as short pulses as possible, while having several nJ of pulse energy and the cavity at strictly zero total dispersion.Item Open Access All-normal-dispersion fiber lasers for frequency metrology(Optical Society of America, 2011) Şenel, Çağrı; İlday, F. Ömer; Kara, O.; Birlikseven, C.; Erdoǧan, C.; Hamid, R.Development of an all-normal-dispersion Yb-doped fiber laser-based frequency comb is reported. Repetition-frequency stabilization to the cesium standard, amplitude and phase noise measurements indicate low-noise performance. ©2011 Optical Society of America.Item Open Access Development and characterization of all-normal dispersion fiber laser for frequency comb generation(Optical Society of America, 2011) Şenel, Çağrı; İlday, F. Ömer; Kara O.; Hamid, R.; Erdoğan, C.Development of an all-normal-dispersion Yb-doped fiber laser-based frequency comb is reported. Repetition-frequency stabilization to the cesium standard, amplitude and phase noise measurements indicate low-noise performance. © 2011 Optical Society of America.Item Open Access Long-term repetition-frequency stabilization of all-normal-dispersion Yb-doped fiber laser to the cesium standard(OSA, 2010) Ülgüdür, Coşkun; İlday, Ömer Fatih; Hamid, R.Repetition-frequency stabilization of a Yb-doped fiber laser to the Cesium standard is reported. Laser amplitude and phase noise is characterized. Performance is limited to 2x10-14 at 100000 averaging time by intrinsic stability of the Cs-standard.Item Open Access Nonlinearity management: from fiber oscillators to amplifiers(IEEE, 2016) İlday, Fatih Ömer; Şenel, Ç.; Hamid, R.; Teamir, Tesfay G.; Pavlov, Ihor; Teğin, Uğur; Ergeçen, E.; Elahi, Parviz; Iegorov, R.While the standard approach to performance scaling in fiber lasers seeks to reduce nonlinear effects through chirping or mode scaling, I will review recent progress in a complementary approach, whereby the governing dynamics are meticulously exploited towards achieving superior performance.Item Open Access Sub-50 fs all-fiber Yb-doped laser with anomalous-dispersion photonic crystal fiber(IEEE, 2013) Zhang, Zewang; Cenel, C.; Hamid, R.; İlday, F. ÖmerAn intense research effort has been channelled into improving mode-locked Yb-fiber oscillators in recent years. Despite efforts in all-normal dispersion oscillators, dispersion management is evidently necessary to reach pulse durations below 50 fs. This is implemented most commonly with bulk optical components in Yb-doped fiber lasers. Increased robustness remains a valuable trait, for which all-fiber-integration is highly desirable. Photonic crystal fibers (PCF) with anomalous dispersion have small mode field diameters, enhancing nonlinear effects and usually are birefringent. The first mode-locked laser to incorporate a PCF was reported in 2002 [1]. However, mode-locking was not self-starting owing to the residual birefringence of the PCF Since then, a number of dispersion-managed Yb-doped fiber lasers using PCFs and all-fiber-integrated lasers have been reported. After 10 years, no all-fiber-integrated Yb-fiber laser has been demonstrated to support pulses below 60 fs [2]. © 2013 IEEE.Item Open Access Sub-50 fs Yb-doped laser with anomalous-dispersion photonic crystal fiber(Optical Society of America, 2013) Zhang, Z.; Şenel, Ç.; Hamid, R.; Ilday, F. Ö.We report on the generation of 42 fs pulses at 1 μm in a completely fiber-integrated format, which are, to the best of our knowledge, the shortest from all-fiber-integrated Yb-doped fiber lasers to date. The ring fiber cavity incorporates anomalous-dispersion, solid-core photonic crystal fiber with low birefringence, which acts as a broadband, in-fiber Lyot filter to facilitate mode locking. The oscillator operates in the stretched-pulse regime under slight normal net cavity dispersion. The cavity generates 4.7 ps long pulses with a spectral bandwidth of 58.2 nm, which are dechirped to 42 fs via a grating pair compressor outside of the cavity. Relative intensity noise (RIN) of the laser is characterized, with the integrated RIN found to be 0.026% in the 3 Hz-250 kHz frequency range.Item Open Access Tailored design of mode-locking dynamics for low-noise frequency-comb generation(American Physical Society, 2018) Şenel, Ç.; Hamid, R.; Erdoǧan, C.; Çelik, M.; İlday, Fatih ÖmerWe report a mode-locked laser design using Yb-doped fiber lasers for low-noise frequency-comb generation. The frequency comb covers the spectral range from 700 to 1400 nm. Although this range is more practical for many measurements than that produced by the more commonly used Er-fiber lasers, it has been addressed in only a handful of reports, mainly due to the difficulty of generating a fully coherent supercontinuum at 1μm. We overcome this difficulty by a tailored design of the mode-locking dynamics that succeeds in generating energetic 33-fs-long pulses without even using higher-order-dispersion compensation, while ensuring that the laser operates with net zero cavity dispersion for low-noise supercontinuum generation. After locking to a Cs atomic clock, this frequency comb is used for absolute-frequency measurements of a Nd:YAG-I2 laser to verify its accuracy by comparison with results from the International Committee for Weights and Measures. After this verification, it is further used to measure the absolute frequency of a 543-nm two-mode stabilized He-Ne laser, which is routinely used for length measurements in our institute, thus verifying its practical utility in metrology applications. The entire setup is built with readily available components for easy duplication by other researchers.