Multielement (P-Yb-Zr-Ce-Al-Ca) fiber for moderate-power laser application with enhanced photodarkening resistivity

Multielement (ME) (P-Yb-Zr-Ce-Al-Ca) nanophase separated silica-glass-based optical fiber is fabricated through a conventional-modified chemical vapor deposition (MCVD) process, coupled with solution doping technique. The lasing and photodarkening behaviors of this ME fiber have been demonstrated and compared, in terms of its photodarkening (PD) performance at moderate pump powers (tens of Watts), with standard Yb-doped fiber with phospho-alumino-silicate (PAS) glass composition, which clearly reveals that the ME-Yb doped fiber is a promising candidate for laser applications with enhanced PD resistivity

Passively Q-switched fiber laser utilizing new hafnium–bismuth–erbium co-doped fiber as saturable absorber

A stable all-fiber passively Q-switched erbium-doped fiber laser emitting at 1559 nm is proposed and demonstrated using an 8-cm-long hafnium–bismuth–erbium co-doped fiber (HBEDF) as a saturable absorber (SA). The HBEDF is fabricated in-house and has a linear absorption of around 5.2 dB at the laser operating wavelength of 1559 nm. The Q-switching pulses are obtained with an input pump power ranging from 50 to 121 mW. It has the pulse repetition rate of 81.57 kHz, the shortest pulse width of 3.31 µs, output power of 10 mW, pulse energy of 123 nJ and peak power of 37.3 mW at the maximum pump power of 121 mW. The corresponding signal-to-noise ratio of the electrical spectrum is measured to be around 70 dB, which indicates the stability of the laser. To the best of our knowledge, this is the first demonstration of the deployment of HBEDF SA in generating a robust and steady pulsed laser in 1.5-micron region. © 2019, Indian Association for the Cultivation of Science

Erbium-Doped Zirconia-Alumina Silica Glass-Based Fiber as a Saturable Absorber for High Repetition Rate Q-Switched All-Fiber Laser Generation

We propose and demonstrate a Q-switched erbium-doped fber laser (EDFL) using an erbium-doped zirconiaalumina silica glass-based fber (Zr-EDF) as a saturable absorber. As a 16-cm-long Zr-EDF is incorporated into a ring EDFL cavity, a stable Q-switching pulse train operating at 1565 nm wavelength is successfully obtained. The repetition rate is tunable from 33.97 kHz to 71.23 kHz by increasing the pump power from the threshold of 26 mW to the maximum of 74 mW. The highest pulse energy of 26.67 nJ is obtained at the maximum pump power

Q-switched hafnium bismuth erbium-doped fiber laser with bismuth (III) telluride based saturable absorber

In this work, we fabricated the Bismuth (III) Telluride (Bi2Te3) based saturable absorber (SA) by embedding the material into polyvinyl Alcohol (PVA) film. By incorporating the film inside laser cavity with a homemade Hafnium Bismuth Erbium-doped fiber (HBEDF) as a gain medium, a stable Q-switched fiber laser was generated to operate at 1532 nm region. The repetition rate of the laser was tunable from 41.1 to 61.0 kHz while corresponding pulse width shrinks from 9.46 to 5.48 µs as the 980 nm pump power rises from 69 to 122 mW. The maximum pulse energy was 31.5 nJ. To the best of our knowledge, this is the first report on the Q-switched fiber laser using n relatively short length of HBEDF as the gain medium

Erbium-Doped Zirconia-Alumina Silica Glass-Based Fiber As A Saturable Absorber For High Repetition Rate Q-Switched All-Fiber Laser Generation

We propose and demonstrate a Q-switched erbium-doped fiber laser (EDFL) using an erbium-doped zirconia-alumina silica glass-based fiber (Zr-EDF) as a saturable absorber. As a 16-cm-long Zr-EDF is incorporated into a ring EDFL cavity, a stable Q-switching pulse train operating at 1565 nm wavelength is successfully obtained. The repetition rate is tunable from 33.97 kHz to 71.23 kHz by increasing the pump power from the threshold of 26 mW to the maximum of 74 mW. The highest pulse energy of 26.67 nJ is obtained at the maximum pump power

A Flat-Gain Double-Pass Amplifier with New Hafnia-Bismuth-Erbium Codoped Fiber

An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber (HBEDF) as a gain medium. The HBEDF is fabricated using a modified chemical vapor deposition in conjunction with solution doping. The fiber has an erbium ion concentration of 12500 ppm. At the optimum length of 0.5 m, the HBEDF amplifier (HBEDFA) achieves a flat gain of 26 dB with a gain variation of less than 1.5 dB within a wavelength region from 1530 to 1560nm when the input signal and pump power are fixed at -30dBm and 140mW, respectively. On the other hand, at the input signal power of -10 dBm, the HBEDFA also achieves a flat gain of 14.2 dB with a gain variation of less than 2.5 dB within a wide wavelength region from 1525 to 1570 nm. Compared with the conventional zirconia erbium co-doped fiber based amplifier, the proposed HBEDFA obtains a more efficient gain and lower noise figure. For an input signal of -30 dBm, the gain improvements of 6.2 dB and 4.8 dB are obtained at 1525nm and 1540 nm, respectively

Compact and flat-gain fiber optical amplifier with Hafnia-Bismuth-Erbium co-doped fiber

For the first time, we demonstrated a compact Erbium-doped fiber amplifier (EDFA) using a newly developed Hafnia Bismuth Erbium co-doped fiber (HBEDF) as a gain medium. The HBEDF was fabricated using a modified chemical vapor deposition process in conjunction with solution doping technique. The fiber has high doping levels of Erbium ion of 12,500 wt ppm through incorporation of Hafnium and Bismuth ions, which prevents the clustering effect. At the input signal power of −10 dBm, a flat gain of 10.9 dB is obtained from the wavelength region of 1525 to 1565 nm with a gain variation of less than ± 0.5 dB. The noise figure is maintained below 4.4 dB at the flat-gain region. The proposed amplifier has the potential applications in dense wavelength division multiplexing communication system due to its simplicity and compact design

Titanium dioxide doped fiber as a new saturable absorber for generating mode-locked erbium doped fiber laser

This work reports on the use titanium dioxide doped fiber (TiO2DF) as a passive saturable absorber (SA) in generating stable and self-starting mode-locked pulse laser in Erbium doped fiber laser (EDFL) ring cavity. The TiO2DF SA is a self-made fiber with 20 cm in length. It has a core diameter of 45 μm, the numerical aperture (NA) of 0.21, core composition of Silica-Titanium (Si-Ti) and cladding composition of Silica Oxides (SiO2). The TiO2DF SA has a wide-band linear absorption profile which also covers the mode-locked laser operating wavelength of 1553 nm. The TiO2DF serves as a great SA due to the presence of anatase crystalline form of TiO2 which provide saturable optical losses in the laser cavity. Results show that reliable mode-locked pulse is observed as the pump power raises from 106 mW to 142 mW. Within this range of pump power, a nearly constant repetition rate within the range of 0.984 MHz to 0.990 MHz is obtained. The actual pulse width seen from the autocorrelator is about 9.74 ps. Both, the maximum peak power of 878 mW and the maximum pulse energy of 8.56 nJ are calculated at the maximum pump power (142 mW). The fundamental frequency of the EDFL mode-locked pulse laser has a signal to noise ratio (SNR) of 54 dB. Our demonstration shows that the TiO2DF-SA is reliable and quite promising in generating EDFL mode-locked pulse laser

Titanium dioxide fiber saturable absorber for Q-switched fiber laser generation in the 1-micrometer region

A passively Q-switched ytterbium-doped fiber laser (YDFL) operating at 1062 nm was demonstrated by using a segment of 20 cm titanium dioxide-doped fiber saturable absorber (TiO 2 DF SA). The Q-switched YDFL emerged stably with tunable repetition rates ranging from 32 kHz to 53 kHz as the pump power rose from 109 mW to 233 mW. Within this range of pump power, a maximum output power of 10.1 mW, maximum peak power of 75 mW, and maximum pulse energy of 191 nJ were obtained. The narrowest pulse width of 2.55 μs was attained at the maximum pump power of 233 mW, while the signal-to-noise ratio of the fundamental frequency was 47 dB. This demonstration reveals that the proposed TiO 2 DF SA is feasible for constructing a flexible and reliably stable Q-switched pulsed fiber laser in the 1-micrometer region. © 2019 Optical Society of America