Characterization of a tunable three-section slotted Fabry-Perot laser for advanced modulation format optical transmission

In this paper we report on the characterization of a narrow linewidth three-section tunable slotted Fabry-Perot laser. The SMSR of the 25 available 100-GHz ITU channels is above 30 dB, whereas their average linewidth is 538 kHz with a maximum below 800 kHz. The RIN spectra of six different channels are also measured and a maximum average RIN of −135 dB/Hz is obtained. The linewidth effect of the laser in a 1.25 Gb/s DPSK transmission system is investigated by comparing the performance between the slotted Fabry-Perot laser and a commercial SG-DBR laser respectively. Error free transmission of the slotted Fabry-Perot laser shows the benefit of the narrow linewidth of the device for systems employing advanced modulation formats.     

Etched facet and semiconductor/air DBR facet of a AlGaInP laser diode prepared by focused ion beam milling

The study of focused ion beam (FIB) milling for making etched facet and semiconductor/air distributed Bragg reflector (DBR) facets of AlGaInP-based red laser diodes (LD) is presented in this letter. For the Ga ion beam current of 100 pA at fixed accelerated voltage 30 kV, FIB milling rate of GaAs was found to be 0.46 μm³/nC. As a trade-off between high reflectivity and enough technical tolerance, the combination of third Bragg orders of semiconductor wall and air gap was chosen. The deeply etched mirror and distributed Bragg reflector facet consisting of pairs of semiconductor wall/air gap on laser diodes (LD) cavity facets with vertical sidewall on AlGaInP LDs were fabricated by focused Ga ion beam milling. Comparison of the AlGaInP LD with the mirrors between cleaved and FIB made facet was given and discussed.     

The simulation of self-mixing interference effects in three-section DBR lasers

The self-mixing interference in three-section distributed Bragg reflector (DBR) lasers is analyzed based on the model of F-P cavity and coupling wave equation. The oscillating frequency and threshold variation are deduced. The influence of internal and external parameters on the output intensity and the inclination degree of waveform are discussed in simulation.     

Lateral characteristics improvements of DBR laser diode with tapered Bragg grating

Broad area semiconductor laser (BAL) has poor lateral beam quality due to lateral mode competition, which limits its application as a high-power optical source. In this work, the distributed Bragg reflector laser diode with tapered grating (TDBR-LD) is studied. By changing the lateral width, the tapered grating increases the loss of high-order lateral modes, thus improving the lateral characteristics of the laser diode. The measuring results show that the TDBR-LD can achieve a single-lobe output under 0.9 A. In contrast to the straight distributed Bragg reflector laser diode (SDBR-LD), the lateral far field divergence of TDBR-LD is measured to be 5.23° at 1 A, representing a 17% decline. The linewidth of TDBR-LD is 0.4 nm at 0.2 A, which is reduced by nearly 43% in comparison with that of SDBR-LD. Meanwhile, both of the devices have a maximum output power value of approximate 470 mW.     

A simple tunable short-pulse XeCl laser with high spectral brightness

A simple tunable short-pulse XeCl laser system with a compact Blumlein circuit is described. In this system, radiation from a XeCl amplifier in order to achieve a wide tunable range and high spectral brightness. The generated radiation is tunable over 307.6–308.6 nm and the maximum peak power is 3 MW. Output pulse duration is shorter than 0.8 ns FWHM with a bandwidth of about 4 pm.     

Simultaneous oscillation of several independently tunable spectral lines in a distributed feedback dye laser

A simple method is proposed which allows obtaining distributed-feedback laser action simultaneously at several spectral lines of any wavelength with independent tuning within the gain profile of the dye.     

Solvent effects on the spectral and gain characteristics of a DAMC dye laser

Small signal gains of a 7-diethylamino 4-methyl coumarin (DAMC) dye laser in a variety of solvent environments have been experimentally determined from the super-radiant emission of these dye solutions. The study suggests that polar, hydrogen-bonding solvents appear to be most suitable for producing high gain in the DAMC dye laser.     

微小孔径激光器的光谱特性综述

微小孔径激光器(Very-small-aperture laser,VSAL)是近年发展起来的新型有源纳米激光光源。出射光端面的孔径形状是决定其性能的重要因素之一。多种异形孔径被先后提出并证明能极大地提高VSAL的出射效率。相关研究结果表明,常规孔径形状的通光效率随入射波长的增大急剧下降,但异形孔径的通光效率会出现一个谐振峰,在谐振峰位置通光效率得到了显著的提高。通过改变孔径形状参数或增加表面纳米形貌结构,可以调整纳米孔径本身的谐振波长峰值,改善VSAL的性能。综述了纳米孔径的光谱特性以及利用这种特性优化VSAL的性能,并对未来的研究前景做了适当的展望。     

Calculating the spectral and time characteristics of a titanium sapphire laser

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 69–73, January, 1991.     

Mode-locked ytterbium fiber laser tunable in the 980-1070-nm spectral range

Spectral tuning of a mode-locked Yb-doped fiber laser over a 90-nm range is reported. Using semiconductor saturable absorber mirrors in a fiber laser cavity incorporating a grating-pair dispersive delay line, we obtain reliable self-starting mode locking over the whole tuning range. The wide tuning range is achieved by optimization of reflection characteristics and bandgap energy of the multiple-quantum-well semiconductor saturable absorber and by proper engineering of the laser cavity.     

Transmission of 20 Gb/s PAM-4 signal over 20 km optical fiber using a directly modulated tunable DBR laser

We report 20 Gb/s transmission of four-level pulse amplitude modulation(PAM) signal using a directly modulated tunable distributed Bragg reflector(DBR) laser. Transmission distance over 20 km was achieved without using optical amplifiers and optical dispersion compensation modules. A wavelength tuning range of 11.5 nm and a 3 dB bandwidth greater than 10 GHz over the entire wavelength tuning range were obtained.     

Frequency doubling of a fibre-amplified 1083 nm DBR laser

A good frequency standard is required at 1083 nm for measurements on the fine structure of helium and of the fine structure constant. Several milliwatts of CW frequency-doubled light offers the prospect of stabilisation to a Doppler-free hyperfine transition in molecular iodine. The 1083 nm emission of an extended-cavity DBR diode laser has been amplified using an ytterbium-doped fibre amplifier, and applied to a type-I phase matched Mg:LiNbO₃ crystal in a high-Q fundamental-resonant cavity for frequency doubling. The amplifier gain at 1083 nm under typical operating conditions was 13.8 dB, with a coherent output power up to 63 mW, limited by the maximum signal input power. The doubling cavity Q was , and about 70% of the incident power was coupled in. The maximum 2nd-harmonic conversion efficiency exceeded 20% and provided an output power of 3.7 mW for making continuous frequency scans of up to 600 MHz in the green. An optical spectrum analyser at 541.5 nm showed fringes of 4.6 MHz full width half maximum, close to the instrumental width. Received: 25 February 1998 / Revised and Accepted: 28 May 1998     

Mode-selection characteristic of the symmetrical three-section composite-cavity InGaAsP/InP semiconductor laser

Simulation and experimental studies of the mode-selection, characteristic of the symmetrical three-section composite-cavity InGaAsP/InP semiconductor laser are reported. The mode-selection property of this laser is explained in terms of the wavelength-dependent effective reflectance. The effective reflectance has periodic variations with wavelength, the period being determined by the dimensions of the cavity. The modulation in the effective reflectance in symmetrical three-section structure lasers is about twice that in two-section structure lasers.     

Step-like optical frequency sweep generator using a DBR laser

A simple system for producing a step-like optical frequency sweep is proposed and demonstrated using a distributed Bragg reflector laser as a light source and a Fabry-Perot resonator as a frequency discriminator. Such a step-like sweep is realized by changing the injection current continuously.     

Analysis of the relative intensity noise behaviour in tunable two- and three-section distributed Bragg reflector lasers

A theoretical analysis is made of the relative intensity noise (RIN) in tunable two- and three-section distributed Bragg reflector (DBR) lasers by taking into account the actual frequency dependence of the Bragg reflector. The RIN is shown to depend significantly on the tuning current, especially at low frequencies and for low and moderate values of the grating coupling coefficient. For high values of this coefficient the dependence is insignificant when the tuning is performed through the DBR section, in accordance with the experimental results recently reported. The RIN spectrum is more significantly affected, however, when the phase control current in the three-section device is used for tuning.     

Fabrication of widely tunable ridge waveguide DBR lasers for WDM-PON

We report the fabrication of widely tunable ridge waveguide distributed Bragg reflector(DBR) lasers with InGaAsP butt-joint as grating material. The shape of the butt–joint interface is found to have significant effect on the properties of the lasers. It is shown that irregular mode jumps during wavelength tuning can be avoided by a V-shaped butt–joint interface. From the fabricated device, 23 channels with 0.8 nm spacing and greater than 35 dB side mode suppression ratios are obtained. The different tuning characteristics of the ridge waveguide and the previously reported buried ridge stripe DBR lasers are discussed. Combined with the wide tuning range and the simple structure, the ridge waveguide DBR lasers are promising for use in wavelength division multiplexing passive optical networks(WDM-PONs).