Browsing by Author "Chiu, IH"

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1.2-ps mode-locked semiconductor optical amplifier fiber laser pulses generated by 60-ps backward dark-optical comb injection and soliton compression
(2005-02-07)
Lin, GR
;
Chiu, IH
;
Wu, MC
;
光電工程學系
;
Department of Photonics
Optically harmonic mode-locking of a semiconductor optical amplifier fiber laser (SOAFL) induced by backward injecting a dark-optical comb is demonstrated for the first time. The dark-optical comb with 60-ps pulsewidth is generated from a Mach-Zehnder modulator, which is driven by an electrical comb at a DC offset of 0.3V(pi). Theoretical simulation indicates that the backward injection of dark-optical comb results in a narrow gain window of 60 ps within one modulating period, providing a cross-gain-modulation induced mode-locking in the SOAFL with a shortest pulsewidth of 15 ps at repetition frequency of 1 GHz. The mode-locked SOAFL pulsewidth can be slightly shortened to 10.8 ps with a 200m-long dispersion compensating fiber. After nonlinearly soliton compression in a 5km-long single mode fiber, the pulsewidth, linewidth and time-bandwidth product become 1.2 ps, 2.06 nm and 0.31, respectively. (C) 2005 Optical Society of America.
110-pJ and 410-fs pulse at 10 GHz generated by single-stage external fiber compression of optically injection-mode-locked semiconductor optical amplifier fiber laser
(2006-05-01)
Lin, GR
;
Chiu, IH
;
光電工程學系
;
Department of Photonics
We demonstrate the high-power amplification and single-stage fiber-based pulse compression of a traveling-wave semiconductor optical amplifier (TWSOA) fiber ring laser (SOAFL), which is optically mode-locked by backward injecting the TWSOA with a dark-optical-comb at repetition frequency of 10 GHz. A negatively chirped SOAFL pulsewidth of 5.4 ps is compensated and shortened to 3.9 ps by a 75-m-long dispersion compensating fiber. With a single-stage pulse compression in a single-mode-fiber spool, the SOAFL pulses with input average power of 1.7 W can further be compressed to a pulsewidth of 410 fs, corresponding to a pulse compressing ratio of nearly ten. The maximum average output power of the amplified SOAFL pulse is up to 1.1 W, corresponding to the peak power and pulse energy of > 0.27 kW and 110 pJ, respectively.
A 3.5-ps mode-locked semiconductor optical amplifier fiber laser generated by 60-ps backward optical dark pulse-train injection
(2005)
Chiu, IH
;
Liao, YS
;
Chang, YC
;
Lin, GR
;
光電工程學系
The relationship between the backward optical injection waveform and the mode-locked Pulse shape of semiconductor optical amplifier fiber laser (SOAFL) is studied. The SOA plays both the roles of a gain medium and an optically controlled modulator in this work. The injected optical comb-like bright and dark pulse-train with 60-ps pulsewidth was generated using a Mach-Zehnder intensity modulator (MZM) which DC-biased voltage of 1.7 V and 7.2 V, respectively. The backward injection of optical dark pulse-train results in a wide gain-depletion width (and a narrow gain window) within one modulation period, which is necessary for perfect mode-locking the SOAFL. In opposite, the backward injection of short optical pulse of bright optical pulse-train only causes a less pronounced gain-depletion effect. Such a broadened gain window can hardly initiate the mode-locking process. The backward comb-like dark pulse-train modulation IS Much easier to initiate harmonic mode-locking in the SOAFL than the bright pulse-train or sinusoidal-wave, wave injection, which generates pulsewidth as short as 15 ps at 1 GHz. After propagating through 195m-long dispersion-compensating fiber, the pulsewidth of the mode-locked SOAFL can be linearly compressed to 13.5 ps. The linewidth and time-bandwidth product of the compressed SOAFL pulses are 1.78 nm and 0.8, respectively. The pulsewidth can further be nonlinearly compressed by using a 4695m-long single-mode fiber. The shortest mode-locked SOAFL pulsewidth of 3.5 ps at repetition frequency of I GHz by using cross-gain modulation technique is reported for the first time.
Femtosecond wavelength tunable semiconductor optical amplifier fiber laser mode-locked by backward dark-optical-comb injection at 10 GHz
(2005-10-31)
Lin, GR
;
Chiu, IH
;
光電工程學系
;
Department of Photonics
Femtosecond nonlinear pulse compression of a wavelength-tunable, backward dark-optical-comb injection harmonic-mode-locked semiconductor optical amplifier based fiber laser (SOAFL) is demonstrated for the first time. Shortest mode-locked SOAFL pulsewidth of 15 ps at 1 GHz is generated, which can further be compressed to 180 fs after linear chirp compensation, nonlinear soliton compression, and birefringent filtering. A maximum pulsewidth compression ratio for the compressed eighth-order SOAFL soliton of up to 80 is reported. The pedestal-free eighth-order soliton can be obtained by injecting the amplified pulse with peak power of 51 W into a 107.5m-long single-mode fiber (SMF), providing a linewidth and time-bandwidth product of 13.8 nm and 0.31, respectively. The tolerance in SMF length is relatively large (100- 300 m) for obtaining <200fs SOAFL pulsewidth at wavelength tuning range of 1530-1560 nm. By extending the repetition frequency of dark-optical-comb up to 10 GHz, the mode-locked SOAFL pulsewidth can be slightly shortened from 5.4 ps to 3.9 ps after dispersion compensating, and further to 560 fs after second-order soliton compression. The lasing linewidth, time-bandwidth product and pulsewidth suppressing ratio of the SOAFL soliton become 4.5 nm, 0.33, and 10, respectively. (c) 2005 Optical Society of America.
Supermode-noise-free eighth-order femtosecond soliton from a backwar dark-optical-comb-injection mode-locked semiconductor optical amplifier fiber laser
(2006-03-15)
Lin, GR
;
Pan, CL
;
Chiu, IH
;
光電工程學系
;
Department of Photonics
A backward dark-optical-comb-injection mode-locked semiconductor optical amplifier fiber laser (SOAFL) with a femtosecond pulse width and an ultrahigh supermode-noise suppressing ratio (SMSR) is primarily demonstrated. The mode-locked SOAFL pulse with a spectral linewidth of 0.45 nm is shortened from 15 to 8.6 ps under chirp compensation in a 420 m long dispersion-compensated fiber, corresponding to a time-bandwidth product of 0.48. The eighth-order soliton is obtained by the nonlinearly soliton's compression of the chirp-compen sated SOAFL pulse in a 112 m long single-mode fiber at an input peak power of 51 W, providing the pulse width, the linewidth, and the nearly transform-limited time-bandwidth product are < 200 fs, 13.8 nm, and 0.34, respectively. The phase noise and integrated timing jitter at an offset frequency below 1 MHz are -105 dBc/Hz and 0.8 ps, respectively. An ultrahigh pulse-compression ratio of 43 and a SMSR of 87 dB for the eighth-order SOAFL soliton are reported. (c) 2006 Optical Society of America.