Analysis of the frequency noise of tunable multisection DBR lasers

A theoretical analysis is performed of the frequency noise in tunable two- and three-section distributed Bragg reflector (DBR) laser diodes (LDs), taking into account the nonlinear gain compression effect. For a two-section DBR LD the frequency noise is shown to depend significantly on the tuning current, particularly at low frequencies (below the gigahertz range) and for low and moderate values of the grating coupling coefficient. For high values of this coefficient the tuning dependence is generally negligible when the tuning is performed only through the DBR section, but it becomes significant when using the phase control current in a three-section device. It is shown that the enhancement factor for the spontaneous emission rate due to the longitudinal field dependence increases significantly with tuning for low values of the grating coupling coefficient     

A tunable interdigital electrode (TIE) DBR laser for single-currentcontinuous tuning

A tunable interdigital electrode distributed Bragg reflector (TIE-DBR) laser is proposed. The device provides single-current continuous-wavelength tuning without any external circuits, since the wavelength shift matching between the Bragg and the longitudinal cavity mode can be obtained in this structure. A continuous tuning in the 4.6-nm wavelength range with sufficient side-mode suppression is achieved with a 1.55-μm TIE DBR laser     

Electronically tunable, 1-W CW, near-diffraction-limited monolithicflared amplifier-master oscillator power amplifier (MFA-MOPA)

An electronically tunable monolithic flared amplifier master oscillator power amplifier structure is described. This device is composed of a DBR laser tunable by free-carrier injection integrated with a flared amplifier, and generates 1-W CW of near-diffraction-limited, single mode power at λ~980 mm, while allowing wavelength tuning over a 6-Å range using a tuning current of 30 mA. This device is useful in applications requiring high power, high beam quality, and precise wavelength control simultaneously such as in frequency doubling     

一种长波长MOEMS可调谐滤波器的结构设计和分析

提出了一种微光机电系统(MOEMS)可调谐滤波器结构,该结构采用GaAs/AlGaAs作为下分布布拉格反射镜(DBR),GaAs和SiO2/Si介质膜作为上DBR,空气作为腔.按照波分复用系统的性能要求对MOEMS可调谐滤波器各项参数,如带宽、峰值透射率、挠度和调谐速度等进行了分析和设计.研究了挠度和调谐速度与梁厚度、宽度、长度等参数的关系.结果表明挠度与长度成正方向变化,同梁厚度、宽度成反方向变化,而调谐速度与各参数的关系恰好相反.     

Over 1100 nm wavelength tuning in superstructure grating (SSG) DBR lasers

A broad range tuning of over 100 nm in tunable DBR lasers with superstructure grating (SSG) is reported. The SSG reflectors for 100 nm were designed and patterned by electron beam lithography. 1.55 mu m DBR lasers with SSG reflector operate in a single mode with a tuning range of 83 nm under CW conditions. With inclusion of the multimode operating region, the tuning range becomes as wide as 103 nm.<>     

A theoretical analysis of linewidth broadening in frequency tunableDBR lasers

Linewidth broadening in frequency tunable distributed-Bragg-reflector (DBR) lasers with tuning sections is analyzed. The analysis is based on a simplified two-section single-mode cavity model and quantum mechanical Langevin treatment. The origin of linewidth broadening is shown to be low frequency excess FM noise caused by carrier fluctuation in the tuning section. A scaling law, which permits optimal device parameter design, is then derived. When a decrease in the carrier lifetime is combined with an increase in the tuning current, linewidth broadening can be suppressed without frequency tuning range reduction     

Monolithic 1.5 ?m hybrid DFB/DBR lasers with 5 nm tuning range

A new tunable single-longitudinal-mode laser structure is reported. This monolithic hybrid DFB/DBR laser can be electrically tuned over a 5 nm wavelength range. The tuning mechanism employs the depression in the refractive index with injected carrier density, and the tuning range is linked to the period of an internal diffraction grating.     

Tunable stair-guide (TSG) DBR lasers for single current continuouswavelength tuning

The authors have developed a new kind of tunable distributed Bragg reflector (DBR) laser that has a tunable stair guide. This allows continuous wavelength tuning when using single current injection. The laser was fabricated by two-step selective area metal organic vapour phase epitaxy. A continuous wavelength tuning range of 3.8 nm at a wavelength of 1.55 μm was achieved     

Subnanosecond tunable laser using a single electroabsorption tuning super structure grating

A new tunable laser structure using a single electroabsorption (EA) tuning super structure grating section for fast wavelength switching operation, has been realized. The tuning mechanism of this absorption change distributed Bragg reflector (DBR) laser is based on a localized absorption variation induced in a multielectrode EA-SSG section. These devices exhibit a 2.5-nm tuning range with three modes and a switching time, between two successive wavelength channels, shorter than 250 ps. The output power variation under tuning is lower than 1.2 dB.     

Analysis of large-signal dynamic characteristics of 10-Gb/s tunable distributed Bragg reflector lasers integrated with electroabsorption modulator and semiconductor optical amplifier based on the time-dependent transfer matrix method

We investigate large-signal dynamic characteristics of tunable distributed Bragg reflector (DBR) lasers with different structures. Because of high chirp and complex structures of tunable DBR lasers, it is difficult to accurately analyze large signal chirp and output pulse shapes with analytical models. Therefore, we apply a numerical model based on the time-dependent transfer matrix method to tunable DBR lasers integrated with electroabsorption modulator (EAM) and semiconductor optical amplifier (SOA). Using this model, we find a suitable /spl alpha/-parameter range in the Bragg grating section (/spl alpha//sub Bragg/-parameter) that produces the tolerable wavelength chirp while maintaining a proper tuning range. To employ the tunable lasers in wavelength division multiplexed networks and improve flexibility of the networks, the tunable lasers should have high output power and low wavelength chirp. According to our simulation results, the EAM section had better be located in between SOA and DBR laser sections to obtain high output power and low wavelength chirp.     

Frequency and wavelength tunable optical microwave source based on a distributed Bragg reflector self-pulsation laser

A frequency and wavelength tunable self-pulsation laser based on DBR laser devices is reported for the first time.This laser generates continuous tunable optical microwave in the range of 1.87-21.81 GHz with 3-dB linewidth about 10 MHz by tuning the injection currents on the front and back gain sections,and exhibits wavelength tuning range from 1536.28 to 1538.73 nm by tuning the injection currents on the grating section.     

A theoretical model of multielectrode DBR lasers

A theoretical model for two- and three-section tunable distributed Bragg reflector (DBR) lasers is presented. The static tuning properties are studied in terms of threshold current, linewidth, oscillation frequency, and output power. Regions of continuous tuning for three-section DBR lasers are presented. Different routes for continuous tuning, when the injection currents to the passive sections are varied, are discussed and the limitations on the continuous tuning range are clarified. By proper control of these currents, a tuning range of approximately 400 GHz is predicted at 1.55 μm wavelength, which is in good agreement with the experimental results published thus far     

Generation of wavelength-tunable transform-limited pulses from amonolithic passively mode-locked distributed Bragg reflectorsemiconductor laser

Generation of wavelength tunable transform-limited picosecond pulses from a monolithic passively mode-locked distributed Bragg reflector (DBR) laser is demonstrated for the first time. A wide tuning range of 12 nm is realized by changing the refractive index of the passive DBR region through a thin-film heater embedded on the DBR section without causing significant changes in pulse characteristics     

Drive current noise induced linewidth in tunable multielectrode lasers

It is shown that drive current noise could lead to an important increase of linewidth and a Gaussian line shape of tunable multielectrode distributed Bragg reflector (DBR) lasers. As an example, the drive current noise induced linewidth (DCNIL) has been measured to be about 120 MHz using a standard DC source through at 50 Omega resistor to drive the Bragg section of a tested DBR laser. For tunable lasers with an electronic tuning efficiency of more than 1 GHz/mA ultralow noise current sources should be used to ensure a negligible DCNIL.<>     

宽带调谐全光纤环形激光器

报道了一种结构简单的全光纤型宽带调谐光纤激光器。利用经过特殊处理的、高温度灵敏度的光纤光栅作调谐元件 ,采用温度调谐方法 ,获得了 38nm的激光波长调谐范围。     

Continuously tunable 1.55-/spl mu/m VCSEL implemented by precisely curved dielectric top DBR involving tailored stress

We present an optically pumped and continuously tunable 1.55-/spl mu/m vertical-cavity surface-emitting laser (VCSEL). The device shows 26-nm spectral tuning range, 400-/spl mu/W maximum output power, and 57-dBm side-mode suppression ratio. The VCSEL is implemented using a two-chip concept. The movable top mirror membrane is precisely designed to obtain a tailored air-gap length (L'=16 /spl mu/m) and a radius of curvature (ROC=4.5mm) in order to efficiently support the fundamental optical mode of the plane-concave resonator. It consists of a distributed Bragg reflector (DBR) with periodic, differently stressed silicon nitride and silicon dioxide multilayers implemented by plasma-enhanced chemical vapor deposition. The lower InP-based part, comprising the InP-InGaAsP bottom DBR and the active region, is grown monolithically using metal-organic vapor phase epitaxy.     

Broad-range wavelength tuning in DBR lasers with super structuregrating (SSG)

Broad-range wavelength tuning is demonstrated in tunable distributed Bragg reflector (DBR) lasers with the super structure grating (SSG) proposed. The SSG is fabricated by electron beam exposure lithography. The grating performance is measured by transmittance characteristics of the SSG reflector. A maximum tuning range of 63 nm is obtained under the CW condition while keeping a single longitudinal mode. In a 50-nm tuning range, the threshold current variation is as low as 5.0-9.5 mA     

Bragg grating fast tunable filter for wavelength divisionmultiplexing

A Bragg grating fast tunable filter prototype working over a linear tuning range of 45 nm with a maximum tuning speed of 21 nm/ms has been realized. The tunable filter system is based on two piezoelectric stack actuators moving a mechanical device thus compressing an apodized fiber Bragg grating. The filter allows both traction and compression and can work in transmission and in reflection. It is designed to work with a channel spacing of 100 GHz according to the ITU specifications for wavelength division multiplexing systems     

Tunable optical filters for dense WDM networks

WDM is currently taking over as the leading technology in point-to-point transmission links. For optical implementation of WDM networks, logical functionalities such as wavelength (channel) selection should be carried out in the wavelength domain; thus, the development of dynamic optical devices is required. One key device is a tunable optical filter. Important features of such a filter include low insertion loss, narrow bandwidth, high sidelobe suppression, large dynamic range, fast tuning speed, a simple control mechanism, small size, and cost effectiveness. Here, an extensive overview of the different technologies used to produce tunable optical filters is presented. Among them, fiber filters such as fiber Bragg gratings and fiber Fabry Perot are the most commercialized, yet inherently limited in their dynamic speeds. For high demanding dynamics, micro-machined and acousto-optic filters can offer a good solution for microsecond tuning speeds. Faster tunable devices, in nanosecond tuning speeds, might emerge out of microresonators, electrooptic filters, and active DBR filters     

Widely tunable 850-nm metal-filled asymmetric cladding distributed Bragg reflector lasers

Broadly tunable distributed Bragg reflector (DBR) lasers utilizing metal-filled surface-etched diffraction gratings were fabricated on a GaAs-unstrained quantum well with AlGaAs core and cladding layers. Devices with 200- and 400-/spl mu/m gratings sections were fabricated. Single-mode devices are fabricated over a broad spectral range, exhibiting over 55 mW of single-facet output power. The optical properties of this structure are analyzed in terms of effective index step between the peak and valley of the grating and scattering loss in the DBR. Discrete devices were fabricated with lasing wavelengths between 846.6 and 862.9 nm at intervals of 1.44nm, representing a range of 16.3 nm. Wavelength tuning by current injection into the DBR section is explored, and a broad tuning range of over 18 nm is measured while single-mode performance is maintained. The spectral linewidth of these devices is measured. The temperature dependence of light versus current, threshold current values, and spectral characteristics are also examined.