ABSTRACT
Semiconductor saturable absorber mirror (SESAM) modelocked high pulse repetition rate (≥10 GHz) diode-pumped solid-state lasers are proven as an enabling technology for high data rate coherent communication systems owing to their low noise and high pulse-to-pulse optical phase-coherence. Compared to quantum well, quantum dot (QD)-based SESAMs offer potential advantages to such laser systems in terms of reduced saturation fluence, broader bandwidth, and wavelength flexibility. Here, we describe the first 10 GHz pulse repetition rate QD-SESAM modelocked laser at 1.55 µm, exhibiting 2 ps pulse width from an Er-doped glass oscillator (ERGO). The 10 GHz ERGO laser is modelocked with InAs/GaAs QD-SESAM with saturation fluence as low as 9 µJ/cm2.
ABSTRACT
Ultrafast VECSELs are compact pulsed laser sources with more flexibility in the emission wavelength compared to diode-pumped solid-state lasers. Typically, the reduction of the pulse repetition rate is a straightforward method to increase both pulse energy and peak power. However, the relatively short carrier lifetime of semiconductor gain materials of a few nanoseconds sets a lower limit to the repetition rate of passively modelocked VECSELs. This fast gain recovery combined with low pulse repetition rates leads to the buildup of multiple pulses in the cavity. Therefore, we applied an active multipass approach with which demonstrate fundamental modelocking at a repetition rate of 253 MHz with 400 mW average output power in 11.3 ps pulses.
Subject(s)
Lasers , Optics and Photonics/methods , Semiconductors , Equipment Design , Lasers, Semiconductor , Lasers, Solid-StateABSTRACT
High pulse repetition rate (≥ 10â GHz) diode-pumped solid-state lasers, modelocked using semiconductor saturable absorber mirrors (SESAMs) are emerging as an enabling technology for high data rate coherent communication systems owing to their low noise and pulse-to-pulse optical phase-coherence. Quantum dot (QD) based SESAMs offer potential advantages to such laser systems in terms of reduced saturation fluence, broader bandwidth, and wavelength flexibility. Here, we describe the development of an epitaxial process for the realization of high optical quality 1.55 µm In(Ga)As QDs on GaAs substrates, their incorporation into a SESAM, and the realization of the first 10â GHz repetition rate QD-SESAM modelocked laser at 1.55 µm, exhibiting â¼2â ps pulse width from an Er-doped glass oscillator (ERGO). With a high areal dot density and strong light emission, this QD structure is a very promising candidate for many other applications, such as laser diodes, optical amplifiers, non-linear and photonic crystal based devices.
ABSTRACT
We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-limited 1536-nm solitons of 255-fs duration with a repetition rate of 50 MHz and average power of 58 mW. We also discuss timing jitter and the trade-off between short pulses and high output power in these lasers.
ABSTRACT
We demonstrate a compact, diode-pumped Nd:GdVO4 laser with a repetition rate of 9.66 GHz and 0.5-W average output power. The laser is passively mode locked with a semiconductor saturable absorber mirror (SESAM), yielding 12-ps-long sech2-shaped pulses. For synchronization of the pulse train to an external reference clock, the SESAM is mounted on a piezoelectric transducer. With an electronic feedback loop of only a few kilohertz loop bandwidth we achieved a rms timing jitter of 146 fs (integrated from 10 Hz to 10 MHz). This is an upper limit because it is mostly limited by the measurement system. The laser setup with a simple linear cavity has a footprint of only 130 mm x 30 mm.
ABSTRACT
We demonstrate a synchronously pumped optical parametric oscillator that emits picosecond pulses at an ~1.55-mum wavelength with a repetition rate as a high as 10 GHz and as much as 100 mW of average power. It is pumped with a diode-pumped passively mode-locked 10-GHz Nd:YVO(4) laser. Because of its high repetition rate and its potential for ultrabroad tunability, this kind of system is useful for telecom applications. It should be scalable to 40 GHz and higher as required for future telecom networks.
ABSTRACT
We describe a diode-pumped Nd:YAG laser that is suitable for micromachining applications and is capable of generating 2.3-mJ pulses at a 4-kHz pulse repetition frequency. The output pulse duration is 20.5 ps. The system is based on a Nd:YAG regenerative amplifier with a novel four-pass postamplifier. The postamplifier incorporates birefringent depolarization compensation and simultaneously prevents parasitic laser oscillation by use of a nonreciprocal beam path. These output pulse energies are achieved without the use of chirped pulse amplification.
ABSTRACT
We present a passively mode-locked Nd:YAG laser with 10.7-W average output power in a diffraction-limited beam. Stable self-starting mode locking with a pulse duration of 16 ps and a pulse energy of 120 nJ is obtained with a semiconductor saturable-absorber mirror. The laser is directly side pumped with two 20-W diode bars. Single-pass frequency doubling in an external 5-mm-thick KTP crystal yields 3.2-W average power at 532 nm.
ABSTRACT
We report on self-starting passively mode-locked diode-pumped 1.3-microm lasers obtained by use of semiconductor saturable absorbers. We achieved pulses as short as 4.6 ps in Nd:YVO(4) and 5.7 ps in Nd:YLF with average output powers of 50 and 130 mW, respectively.
ABSTRACT
We demonstrate the use of a single prism for adjustable dispersion compensation in a mode-locked laser cavity, instead of the standard approach with a prism pair. A simple model based on the prism-pair configuration is presented to determine the group-velocity dispersion by use of ray optics to trace the wavelength-dependent optical axes through the cavity. We experimentally demonstrated this concept with a passively mode-locked diode-pumped Nd:glass laser producing 200-fs pulses with a 200-mW average output power, using only one intracavity prism. The advantages of such a cavity design are simple alignment, reduced loss, and lossless wavelength tunability This technique can be generalized to other angularly dispersive elements such as prismatic output couplers.
ABSTRACT
We demonstrate passively mode-locked diode-pumped Nd:glass lasers with different media such as silicate, phosphate, and fluorophosphate that are homogeneously or inhomogeneously broadened. An antiresonant Fabry-Perot saturable absorber starts and stabilizes the soliton mode-locked Nd:glass lasers, producing pulses as short as 130 fs at an average output power of 100 mW. With a cw Ti:sapphire pump laser we obtain pulses as short as 90 fs.
ABSTRACT
A high-dynamic-range autocorrelation technique was used to characterize the temporal pulse shape of ultrashort laser pulses produced from four separate oscillators. These lasers included two Kerr-lens mode-locked Ti:sapphire oscillators as well as a Nd:glass and a Ti:sapphire oscillator, each passively mode locked by an antiresonant Fabry-Perot semiconductor saturable absorber. It was shown that the Nd:glass oscillator supported a pulse that was temporally clean over 8 orders of magnitude.
ABSTRACT
We present a simple, in situ technique to calculate the small-signal gain of typical solid-state continuous-wave lasers, such as Nd:YAG and Nd:YLF lasers, by measuring the frequency of the relaxation oscillation noise peak. The laser's small-signal gain can be directly calculated from the frequency of the relaxation oscillation with knowledge of the upper-state lifetime, the cavity round-trip time, and total losses, which are typically well-known values. When the laser is pumped many times above threshold the losses do not need to be known accurately. This technique is compared with the traditional method of changing output couplers to establish its accuracy.
ABSTRACT
We demonstrate a self-starting passively mode-locked diode-pumped Cr:LiSAF laser, achieving pulses as short as 98 fs with an average power as high as 50 mW. In continuous-wave operation, we demonstrate 140 mW of output power with a tunability of 100 nm FWHM. These results were achieved by use of lower Cr(3+) doping (1.5%), high-brightness diode lasers pumping from both sides of the crystal, and a low-loss antiresonant Fabry-Perot saturable absorber to start and sustain mode-locked operation.
ABSTRACT
We demonstrate that intracavity filtering and soliton formation in actively mode-locked lasers can lead to pulse shortening by as much as a factor of 30. Pulses as short as 310 fs have been generated from a Nd:glass laser that is mode locked only by an acousto-optic modulator.
ABSTRACT
A diode-pumped Nd:YLF regenerative amplifier operating at 1047 nm produces 88-microJ, 11-ps pulses at a 1-kHz repetition frequency. Switching of the 250-MHz seed pulses with a Pockels cell in the half-wave configuration is achieved with a contrast ratio of 20:1. After 50 round trips, the amplified pulse experiences an overall energy gain of 73 dB when the amplifier is seeded with 4-pJ pulses (1-mW average seed power). At 1 kHz, doubling and quadrupling yields 46 microJ/pulse at 524 nm and 8.1 microJ/pulse at 262 nm, with corresponding conversion efficiencies of 52% and 23%. At 3.5 kHz, the amplifier generated 97 mW of power at 524 nm and 15.8 mW of power at 262 nm.
ABSTRACT
We modeled, designed, and built a 500-MHz acousto-optic mode locker with a diffraction efficiency of 28% per 1 W drive power. The transducer is zinc oxide sputtered onto a sapphire substrate. A new figure of merit is defined for the mode-locker design, which indicates that sapphire is a good substrate material. Pulse widths of less than 10 psec with an average power of 150 mW were achieved from a 500-MHz pulse-rate, diode-pumped, cw mode-locked Nd:YLF laser using a pump power of 700 mW.
ABSTRACT
A diode-pumped Nd:YLF laser has been acousto-optically mode locked at a 2-GHz repetition rate, giving pulse widths of 7 psec with an average power of 135 mW at a wavelength of 1.047 microm. The 2-GHz pulse rate corresponds to a free-space cavity length of 7.5 cm, while the laser's actual cavity length is approximately 6.6 cm. The mode locker consists of a sapphire substrate with a lithium niobate transducer, giving 0.5% loss modulation per watt. Stable mode-locked pulses were achieved for loss modulations of 1% or greater.
ABSTRACT
The timing fluctuations of a mode-locked Nd:YAG laser are reduced by electronic feedback. Timing fluctuations at rates of 50 to 250 Hz are reduced by more than 20 dB, the total timing fluctuations are reduced from 2.9 to 0.9 psec rms, and long-term drift is reduced to 0.5 psec/min. Applications include time-resolved probing experiments and synchronization of lasers.
