Pulse duration

About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.

Quasi-phase-matched parametric chirped pulse amplification systems

Abstract: Use of quasi-phase-matched (QPM) materials for parametric chirped pulse amplification (PCPA) substantially reduces the required pump peak power and pump brightness, allowing exploitation of spatially-multimode and long duration pump pulses. It also removes restrictions on pump wavelength and amplification bandwidth. This allows substantial simplification in pump laser design for a high-energy PCPA system and, consequently, the construction of compact diode-pumped sources of high-energy ultrashort optical pulses. Also, this allows elimination of gain-narrowing and phase-distortion limitations on minimum pulse duration, which typically arise in a chirped pulse amplification system. One example of a compact source of high-energy ultrashort pulses is a multimode-core fiber based PCPA system. Limitations on pulse energy due to the limited core size for single-mode fibers are circumvented by using large multimode core. Limitations on pulse duration and beam quality due to multimode core are circumvented by using a PCPA scheme. Additionally, the large core of the multimode fiber facilitates cladding-pumping by inexpensive and high-power multiple-mode laser diodes.

Independently variably controlled pulsed R.F. plasma chemical vapor processing

Abstract: Semiconductive wafers are processed, i.e., etched or layers deposited thereon, by means of a plasma enhanced chemical vapor processing system wherein the plasma is generated by a train of R.F. power pulses. The pulse repetition rate, pulse length and peak power level of the individual pulses are independently variably controlled to variably control the uniformity of the processing of the semiconductive wafers within the processing gaps.

Tungsten disulphide for ultrashort pulse generation in all-fiber lasers

Abstract: Tungsten disulphide (WS2), which exhibits excellent saturable absorption properties, has attracted much attention in the applications of photonic devices. In this paper, WS2 is applied for the preparation of a saturable absorber (SA). Using the pulsed laser deposition (PLD) method, WS2 is deposited on the side surface of the tapered fiber. In order to obtain larger non-linearity of the SAs with evanescent wave interaction, the tapered fiber had a smaller waist diameter and longer fused zone. Gold film was deposited on the fiber-taper WS2 SAs to improve their reliability and avoid oxidation and corrosion. Employing the balanced twin-detector method, the modulation depth of the fiber-taper WS2 SAs was measured to be 17.2%. With the fiber-taper WS2 SA, a generated pulse with 246 fs duration and a 57 nm bandwidth was obtained at 1561 nm. The electrical signal to noise ratio was better than 92 dB. To our knowledge, the pulse duration was the shortest among the reported all-fiber lasers with transition metal dichalcogenide (TMD) SAs. These results indicate that fiber-taper WS2 SAs with smaller waist diameter and longer fused zone are promising photonic devices for ultrashort pulse generation in all-fiber lasers.

Microfiber-based WS 2 -film saturable absorber for ultra-fast photonics

Abstract: In this paper, we demonstrated a passively mode-locked erbium-doped fiber (EDF) laser by incorporating a tungsten disulfide (WS2) film SA fabricated by pulsed laser deposition (PLD) method. The WS2 film was thickness-dependent, which had two different states: the bulk WS2 [faced to plasma plume] and tiny WS2 flakes [in the shadow of plasma plume]. This SA device demonstrated low insertion loss (IL) and high power tolerance ability. Interestingly, the SA device possessed different nonlinear absorption regimes related with the film states. By employing this new type of SA, we obtained stable fundamental mode-locking (FML) at pump power of 54 mW, and the generated soliton pulse had pulse duration of 675 fs and signal-to-noise ratio (SNR) of 65 dB. At the maximum pump power of 395 mW, we also obtained up to 1 GHz repetition rate of harmonic mode-locking (HML) with pulse duration of 452 fs and SNR of 48 dB. The experimental results show that WS2-PLD film can serve as a promising SA for ultrafast laser systems.

Relativistic X-band BWO with 3-GW output power

Abstract: Results from a study of a relativistic X-band backward-wave oscillator (RBWO) with 3-GW output microwave power are presented. The RBWO was driven by the high-current electron accelerator SINUS-7. The dependence of radiated microwave pulse duration on microwave power was obtained. Pulse shortening occurring at the higher power levels is probably attributable to explosive electron emission from the slow wave structure (SWS). An increase in the cross section of the electrodynamic structure seems to be a way to increase the microwave pulse duration. Experimental results from a moderately oversized X-band RBWO using a resonance reflector are described. This tube can be operated with a low external magnetic field.