Soliton compression and pulse-train generation by use of microchip Q-switched pulses in Bragg gratings

Abstract

Pulse compression and pulse-train generation are demonstrated by use of kilowatt 580 ps pulses generated by a compact (15 cm x 3 cm x 3 cm) microchip Q-switched laser followed by a fiber Bragg grating. A 12-fold pulse compression to 45 ps with five times peak power enhancement is achieved at 1.4 kW through soliton effect compression in the fiber grating. At 2.5 kW, modulational instability leads to a train of high-contrast sub-100 ps pulses. These demonstrations take advantage of the ultrastrong dispersion at frequencies close to the edge of the photonic bandgap. Experimental results are discussed in the context of the nonlinear Schrödinger equation and are compared with simulations of the nonlinear coupled-mode equations.

Pulse train generation by soliton fission in highly nonlinear chalcogenide (As 2 S 3 ) waveguide Bragg grating

“…2b shows the FROG reconstructed shape of the input pulse (dashed) and output pulse train (solid). Although this is not conclusive evidence of soliton formation, such pulse splitting is characteristic of soliton fission, as previously reported [3][4][5]7]. Discussion: In modelling this experiment using the nonlinear coupled mode equations (NLCMEs) and assigning k ¼ 289 cm 21 , representative of a 9.3 nm wide bandgap, we observe pulse splitting of a second-order soliton into its two fundamental solitons [7].…”

“…In previous work conducted in 60 and 100 mm lengths of optical fibre [3,4] and a 6 mm length AlGaAs waveguide [5], each incorporating a Bragg grating, we were able to demonstrate, to different degrees, the formation of optical solitons where the grating was used to accelerate soliton formation. Although the dispersion associated with a Bragg resonance in transmission is very strong near the band edge, it diminishes quickly over a bandwidth similar in width to the bandgap.…”

“…For a perfect uniform grating, such a bandgap would imply a photo-refractive index change of Dn ¼ 0.014 and a corresponding grating strength of k ¼ 289 cm 21 . However, as discussed below, this grating is found to be chirped and to contain defects that reduce its effective strength to k ' 115 cm 21 , still nine times stronger than gratings used previously [3][4][5]. The experiment consists of launching 2 ps pulses from a pulsed, figure-eight modelocked laser and filtering out all but 0.5 nm of the pulse spectrum, resulting in nearly transform limited, 3.9 ps pulses.…”

All-optically tuned fiber Bragg grating delay line by self-pumping

“…Therefore, researches on the tuneable optical delay devices based on slow-light effects have become a focus in recent years. Concerning the slow-light tuneable delay mechanisms, there are two types based on linear and nonlinear methods respectively [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In the linear methods, the maximum of delay time will be limited by delay-bandwidth product of the system because of the Kramers-Kronig relation; moreover the dispersion prevents the effective applications of FBG in high-speed all-optical signal processing [22].…”

Lasing in Dye–Doped Photonic Liquid Crystal Devices

“…Photonic crystals with periodic dielectric structures have attracted great interest from both scientific and technological viewpoints [1][2][3][4][5][6]. Many new physical phenomena including suppression of spontaneous emission, absence of zero fluctuation, energy transfer, bound state of photonic, optical switching and bistability can occur in the structure possessing gaps in the photonic band gap structure.…”