High harmonic generation from solids david reiss

To compensate the high loss induced by the grating-based filter and avoid causing additional nonlinearities, a cladding-pumped third amplifier stage was built with a 2.5-m-long in-house-fabricated Tm-doped fiber with a core diameter of 11Р’В Р’Вµm. The grating-based filter also improved the OSNR of the signal spectrum to >РІР‚вЂ°30Р’В dB. With the FBGs set for achieving maximum power, the transmitted signal had a spectrum with a 3-dB bandwidth of 0.3Р’В nm, but with a double-peak structure, as shown with caption of РІР‚ВFilter setting-1РІР‚в„ў in Fig. Р”Р„ grating-based filter, comprising a pair of circulators and two fiber Bragg gratings (FBGs), was used after the second amplifier to remove further ASE and narrow the bandwidth of the signal spectrum, which was broadened due to the nonlinear effects of self-phase modulation (SPM) and modulation instability (MI). The detailed design consideration of the Tm-doped fiber amplifier system can be found in our previous work. A second 1565-nm core-pumped Tm-doped fiber amplifier, compromised of in-house fabricated single-mode Tm-doped fiber and Er/Yb co-doped fiber laser, increased the signal power to 48Р’В mW. In spite of the 9.7-dB insertion loss of the EOM and associated polarization-sensitive components, the signal after the EOM had an average power of 1.2Р’В mW with a good optical signal-to-noise ratio (OSNR) of ~РІР‚вЂ°25Р’В dB. The excess amplified spontaneous emission (ASE) generated from the first preamplifier was eliminated by an electro-optic modulator (EOM), which acted as a time gate to pass only the optical pulses. A Tm-doped single-mode fiber (OFS, TmDF200) with a core diameter of ~РІР‚вЂ°4Р’В Р’Вµm, which was core-pumped by an in-house-built Er/Yb co-doped fiber laser (1.5Р’В W at maximum) at 1565Р’В nm, was employed as the first preamplifier providing about 40Р’В dB of gain for the seed pulses. The pulsed seed laser, with ~РІР‚вЂ°100-ps pulse duration, had a spectral bandwidth of 0.9Р’В nm and an average power of ~РІР‚вЂ°1Р’В Р’ВµW. A low-power 1953-nm InGaAs/InP FabryРІР‚вЂњPerot diode was used as a seed for the MOPA, which was gain-switched by electrical pulses at a 1-MHz repetition rate. An output power of 690Р’В mW is obtained at a wavelength of 488Р’В nm.Р”Р‡igure 1 shows the schematic of the Tm-doped fiber master oscillator power-amplifier (MOPA) system. Furthermore, we explored the frequency quadrupling of the ps Tm-doped fiber laser to generate blue light for potential applications such as data storage, displays and spectroscopy. In this paper, we investigate the frequency doubling of a picosecond (ps) Tm-doped fiber laser and demonstrate a conversion efficiency as high as 75% which is, to the best of our knowledge, the highest efficiency yet for a frequency-doubled Tm-doped fiber laser. A narrow-linewidth continuous-wave Tm-doped fiber laser has also been demonstrated giving frequency-doubled output at 970Р’В nm with a conversion efficiency of 32.7%. It has been demonstrated that frequency doubling of Tm-doped fiber lasers can generate 950Р’В nm light with a 60% conversion efficiency in the nanosecond (ns) operation regime. Furthermore, Yb-doped fiber lasers cannot be operated at wavelengths much below 970Р’В nm. To overcome this difficulty, fibers with non-standard geometries need to be carefully designed. However, gain competition between the pure three-level transition and quasi-four-level laser operation at longer wavelengths is a major problem for operation on this zero-phonon line.

Among other solutions, ytterbium (Yb) doped fibers present high emission cross-section around 976РІР‚вЂ°РІР‚вЂњРІР‚вЂ°980Р’В nm when pumped around 915Р’В nm. Solutions based on semiconductor devices have been proposed with electrically modulated distributed Bragg reflectors but can only generate Watt-level peak powers. Short-pulsed 9xx-nm lasers have many attractive applications including medical instrumentation, spectroscopy, remote sensing, and free-space communication. As a result of this broad emission band, such systems are suitable to generate wavelengths in the range of 830РІР‚вЂ°РІР‚вЂњРІР‚вЂ°1025Р’В nm through second harmonic generation (SHG), which includes some wavelengths between 900 and 980Р’В nm that traditional solid-state lasers find hard to achieve. A number of demonstrations have shown that Tm-doped fiber lasers and amplifiers can show gain extending from 1660 to 2050Р’В nm. Thulium (Tm) doped fiber lasers and amplifiers have generated great interest for a wide range of applications, such as gas sensing, material processing and environmental monitoring, due to the broad gain bandwidth of Tm at around 2Р’В Р’Вµm.

High harmonic generation from solids david reiss