Gold Nanorods Saturable Absorber Research Articles

Passively Q-switched 3 μm erbium-doped solid state lasers using gold nanorods as broadband saturable absorber

The gold nanorods with an average aspect ratio of 30 were grown by the three-step seed-mediated wet chemistry growth method, resulting in a broadband spectral response in 3 μm region. Passive Q-switching operation of LD pumped 2.8 μm Er:YSGG and 2.9 μm Er:YAP laser was successfully realized by using the gold nanorods as saturable absorber. With regard to the Er:YSGG laser, the passively Q-switched pulses at 2796 nm with a maximum average output power of 234 mW, a minimum pulse width of 270.8 ns and a pulse repetition rate of 280.4 kHz were achieved. For the combination of Er:YAP and gold nanorods saturable absorber, a maximum average output power of 415 mW was obtained at 2919 nm. The minimum pulse width and pulse repetition rate were 313.2 ns and 196.8 kHz, respectively. The experimental results show that large-aspect-ratio gold nanorods can be used as a promising broadband saturable absorber to generate 3 μm short pulses.

Highly efficient mode-locked and Q-switched Er3+-doped fiber lasers using a gold nanorod saturable absorber

Mode-locked and Q-switched pulsed fiber laser sources with wavelengths of 1.55 μm are widely used in various fields. Gold nanorods (GNRs) have been applied in biomedicine and optics owing to their biocompatibility, easy fabrication, and unique optical properties. This paper presents the analysis of a saturable absorber based on a colloidal gold nanorod (GNR) thin film for dual-function passively mode-locked and Q-switched 1.55-μm fiber lasers. The colloidal GNR thin film possesses superior properties such as a wide operating wavelength range, large nonlinear absorption coefficient, and a picosecond-order recovery time. Its modulation depth and saturation intensity at 1.55 μm are 7.8% and 6.55 MW/cm2, respectively. Passive mode-locked or Q-switched laser operation is achieved by changing the number of GNR thin-film layers. The advantages of these high-quality GNRs in mode-locked and Q-switched fiber lasers with record-high slope efficiency are verified by conducting comprehensive material and laser dynamic analyses. The self-starting mode-locked fiber laser with an efficiency as high as 24.91% and passively Q-switched fiber laser with the maximum energy of 0.403 μJ are successfully demonstrated. This paper presents the novel demonstration of reconfigurable mode-locked and Q-switched all-fiber lasers by incorporating colloidal GNR thin films.

Gold Nanorods as Saturable Absorber for Harmonic Soliton Molecules Generation.

Gold nanorods (GNRs) has been investigated in the field of chemistry, optoelectronics, and medicine for their tenability, compatibility, electromagnetics, and excellent photonics properties. Especially, GNRs, used to generate ultrashort pulse, have been studied recently. However, multiple pulses evolution based on GNRs needs to be further explored. In this article, GNRs are synthesized by seed-mediated growth method, characterized systematically and been chosen as saturable absorber (SA) to apply in ultrafast photonics. The GNRs SA presents a saturable intensity of 266 MW/cm2, modulation depth of 0.6%, and non-saturable loss of 51%. Furthermore, a passively mode-locked erbium-doped fiber laser based on GNRs SA with femtosecond pulse is demonstrated. Thanks to the excellent properties of GNRs, by adjusting the cavity polarization direction with the proposed GNRs SA, soliton molecules operation with spectrum modulation period of 3.3 nm and pulse modulation interval of 2.238 ps is directly obtained. For the most important, 9th-order harmonic soliton molecules have been generated in the laser cavity for the first time. It is demonstrated that GNRs can be a novel type of non-linear optical (NLO) device and have potential applications in the field of ultrafast photonics.

Mode locking and multiwavelength Q-switching in a dumbbell-shaped fiber laser with a gold nanorod saturable absorber

A dumbbell-shaped fiber laser with dual-functional pulsed outputs is demonstrated using a filmy polyvinyl alcohol-based gold nanorods (GNRs) saturable absorber (SA), which can deliver mode-locked soliton and multiwavelength Q-switched pulse. The GNRs-SA is fabricated by seed-mediated method with a modulation depth of 4.1% and nonsaturable loss of 32.9%. When the fiber laser operates in mode-locked regime, stable fundamental solitons with a temporal width of 910 fs and repetition rate of 2.88 MHz are directly generated from the laser cavity. The corresponding spectrum is located at 1560.1 nm with a 3-dB bandwidth of 3.08 nm. When the laser operates in Q-switched regime, more than 5-wavelength oscillation is achieved. The repetition rate of Q-switched monotonically increases from 13.4 to 31.7 kHz and the pulse duration can be significantly narrowed from 6.07 to 3.12 μs by varying the pump power from 128 to 154 mW. The results further expand the applications of GNRs-SA to obtain versatile pulse sources in ultrafast laser field.

Stable Dissipative Soliton Generation From Yb-Doped Fiber Laser Modulated via Evanescent Field Interaction With Gold Nanorods

We demonstrated the dissipative soliton generation from a passively mode-locked ytterbium-doped fiber laser operating at 1041 nm by using evanescent field interaction with gold nanorods (GNR) saturable absorber (SA) experimentally. The GNRs, which have broadband longitudinal surface plasmon resonance absorption from ~800 to ~1500 nm, are synthesized by a seed-mediated growth method, and then composited with a D-shaped fiber to form the GNRs SA. The GNRs SA shows a modulation depth of 9.7% and low saturation intensity of 0.302 MW/cm 2 . With the proposed GNRs SA, a dissipative soliton fiber laser was achieved with pulse duration 162.3 ps, repetition rate of 6.649 MHz at 1041 nm for a pump power of 220 mW. In addition, the signal-to-noise ratio can reach ~77 dB. The experimental result may make inroads for the nonlinear optical applications of the plasmonic nanomaterials.

Gold nanorods saturable absorber for Q-switched Nd:GAGG lasers at 1 μm

A gold nanorod saturable absorber has been synthesized by the seed-mediated growth method characterized in detail. The absorption peak wavelength was 1080 nm, and the modulation depth was measured to be ~9%. The performance of its Q-switched Nd:GAGG lasers at 1061 and 1106 nm has been systematically investigated, respectively. The corresponding shortest pulsewidths were 250 and 480 ns. Our experiment results proved that the GNR-SA is a promising saturable absorber for nanosecond bulk lasers.

A microfiber-based gold nanorod saturable absorber with evanescent field interaction for multi-soliton patterns in a fiber laser

We report on the generation of various multi-soliton patterns in a fiber laser using a microfiber-based gold nanorod saturable absorber (GNR SA). By depositing GNRs onto a microfiber, the nonlinear effect and photo-thermal stability of the GNR SA are both enhanced due to the evanescent field interacting with the nonlinear material GNRs for a relatively long interaction time. Benefiting from a high third-order nonlinear coefficient and the excellent saturable absorption of GNRs, versatile multi-soliton patterns such as random distribution multi-solitons, soliton clusters, soliton molecules, multiple solitons occupying the whole cavity, and soliton flow can be easily obtained by properly adjusting the laser cavity parameter settings. The experimental results contribute to further understanding the physical mechanisms of multi-soliton dynamics, and demonstrate that the microfiber-based GNR SA is an excellent candidate for investigating the nonlinear phenomena in ultrafast fiber lasers.

Passively mode-locked fiber lasers at 1039 and 1560 nm based on a common gold nanorod saturable absorber

We demonstrated passively mode-locked ytterbium and erbium doped fiber lasers operating at 1039 and 1560 nm by using a common gold nanorods (GNRs) saturable absorber (SA). The GNRs with designed aspect ratios were mixed with sodium carboxymethylcelluose to form the GNRs SA film. The film had broadband longitudinal SPR (surface plasmon resonance) absorption from 800 to 1800 nm. By inserting the same film into a ytterbium or erbium doped fiber laser cavity pumped by a 980 nm laser diode, stable passively mode-locked laser operation at 1039 or 1560 nm was achieved for a threshold pump power of ~100 or ~70 mW, respectively. The pulse width, the output power, and the repetition rate of the 1039 nm mode-locked laser were 460 ps, 1.47 mW, and 43.5 MHz for a pump power of ~110 mW, respectively. The corresponding output parameters of the 1560 nm mode-locked laser were 2.91 ps, 2 mW, and 35.6 MHz for a pump power of ~74 mW, respectively. Our results showed that one GNRs SA could be used for constructing broadband mode-locked lasers.

Mode-locked thulium-doped fiber laser at 1982 nm by using a gold nanorods saturable absorber

We demonstrated a passively mode-locked fiber laser operating at 1982 nm by using a gold nanorods (GNRs) saturable absorber (SA). The GNRs SA was fabricated by mixing GNRs with sodium carbonxymethyl cellulose. By inserting the GNRs SA into a Tm-doped fiber laser cavity pumped by a 1570 nm fiber laser, stable passively mode-locking was achieved with a threshold pump power of 224 mW, ~4.02 ps pulses at 1982 nm with a repetition rate of ~37.49 MHz, and a maximum average power of ~6 mW was obtained for a pump power of ~265 mW.

Gold nanorod as saturable absorber for Q-switched Yb-doped fiber laser

We reported on the generation of Q-switched pulse in an Yb-doped fiber laser by using a filmy polyvinyl alcohol (PVA)-based gold nanorods (GNRs) saturable absorber (SA). The GNRs are synthesized through seed-mediated method whose longitudinal surface plasmon resonance (SPR) absorption peak is located at 1038nm. The modulation depth of the GNRs SA is ∼4.06%. By gradually increasing the pump power from 62mW to 128mW, the repetition rate of Q-switched pulse increases from 8.78kHz to 20.78kHz and the pulse duration decreases from 9.43μs to 3.65μs. In addition, the dual-wavelength switchable Q-switched operation was also observed. The obtained results further expand the applications of GNRs SA to the field of Q-switched pulsed fiber lasers at 1.0μm waveband.

Gold nanorod saturable absorber for passive mode-locking at 1 μm wavelength

Gold nanorods (GNRs) were used as a saturable absorber (SA) for passive mode-locking at 1 μm wavelength. The GNR-SA film was fabricated by mixing GNRs with sodium carboxymethylcellulose. The longitudinal surface plasmon resonance absorption of GNRs was used to induce mode-locking. By using the GNR-SA film, stable passive mode-locking at 1039 nm was experimentally demonstrated in an ytterbium-doped fiber laser cavity pumped by a 980 nm laser diode. The laser produced ∼440 ps pulses with a repetition rate of 36.6 MHz and an average output power of ∼1.25 mW for a pump power of ∼82 mW.

Gold nanorods as saturable absorbers for all-fiber passively Q-switched erbium-doped fiber laser

A new type of saturable absorber (SA) based on gold nanorods (GNRs) for all-fiber passively Q-switched erbium-doped fiber laser (EDFL) is realized experimentally. The longitudinal surface plasmon resonance (SPR) absorption of GNRs is used to induce Q-switching. By inserting the GNRs SA in an EDFL cavity pumped by a 980 nm laser diode, stable passive Q-switching is achieved with a threshold pump power of ~27 mW, and 4.8 μs pulses at 1560 nm with a repetition rate of 39.9 kHz are obtained for a pump power of ~275 mW.