Three-section Distributed Bragg Reflector Laser Research Articles

Monolithically Integrated Tunable Three- Section All-Active DBR Laser Diodes With 30 nm Tuning Range

We present a monolithically integrated three-section all-active AlGaInAs/InP tunable distributed Bragg reflector (DBR) ridge waveguide laser diode that uses thermal tuning mechanism and mode-hopping tuning principle to achieve wide-range wavelength tuning. It is similar to the traditional three-section DBR laser structure, including a gain section, a phase section, and a DBR grating section. The difference is that the phase section and the DBR section incorporate the same active quantum well structure as the gain section. In this case, weak effective refractive index changes of the three active sections affected by the current injection will occur since the carrier density is clamped by the threshold gain condition of the DBR laser diode. Despite this limitation, a noncontinuous tuning up to ∼30 nm (1564–1594 nm) can be observed using only current injection at a constant temperature of 25 °C. Significant thermal effects occurred during the tuning process. In addition, a discontinuity is introduced in the tuning because it does not contain a passive region for phase adjustment. However, the device still provides a stable single longitudinal mode output with nine channels, a wavelength spacing of about 4 nm, and a side mode suppression ratio (SMSR) of more than 30 dB. Furthermore, the DBR laser diode can be easily fabricated utilizing the conventional distributed feedback laser diode fabrication process without secondary epitaxy and heater metal. The all-active DBR laser diode will be expected to be applied in the coarse wavelength division multiplexing (CWDM) systems with the advantage of low cost.

A Widely Tunable Three-Section DBR Lasers for Multi-Species Gas Detection

We demonstrate a widely tunable distributed Bragg reflector (DBR) laser operating at 1.8-µm, in which the DBR section was butt-jointed InGaAsP (λ = 1.45 μm) material. Through current and temperature tuning, a widely tuning range of over 11 nm with a side mode suppression ratio (SMSR) higher than 30 dB is obtained. Utilizing this DBR laser, the water and methane detection experiment has been successfully implemented, which illustrates the potential capacity of such DBR laser as the light source used for multispecies gas sensing. The work also illustrates that the butt-joint active-passive integration technology developed for the InGaAsP quantum-wells (QWs) can be successfully applied in the InGaAs QWs.

III-V-on-silicon three-section DBR laser with over 12 nm continuous tuning range.

Device and tuning characteristics of a novel heterogeneously integrated III-V-on-silicon three-section distributed Bragg reflector (DBR) laser are presented. The laser exhibits a continuous wavelength tuning range of more than 12 nm. Thermal tuning is achieved through carrier injection in the passive tuning layer of a III-V tunable twin-guide membrane. Single-mode lasing with a side-mode suppression ratio larger than 30 dB over the entire tuning range is realized through implementation of a sidewall-corrugated silicon-on-insulator waveguide grating as one of the laser mirrors.

Precompensation Techniques to Suppress the Thermally Induced Wavelength Drift in Tunable DBR Lasers

Wavelength drift caused by thermal transients is a major problem in optical routers which use semiconductor tunable lasers for packet switching. Wavelength drift is induced by the temperature variations in laser sections caused by switching of the tuning currents. A thermal model is used to analyze the optical frequency drifts due to the thermal characteristics of the laser chip and its mount. We investigate the impact of thermal effects on switching behavior of a three-section distributed Bragg reflector laser and show numerically that the wavelength drift can be counteracted by using precompensation of passive section currents. Results from numerical simulation show that the wavelength drifts can be suppressed by more than 80%.

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.

Analysis of self-pulsating three-section DBR lasers

The characteristics of a three-section distributed Bragg reflector laser showing self-pulsation have been analyzed using a large signal time-domain traveling-wave simulator. The device dynamic properties have been investigated in all their complexity and analyzed as functions of the linewidth enhancement factor and of the injected current in the active and in the phase control sections. The simulation results have clearly shown the fundamental role of four wave mixing on the laser characteristics (output power, spectrum, etc.) and have been quantitatively correlated with the few available theoretical and experimental results. The considered self-pulsation operation frequencies around 40 GHz are of interest for practical applications.

A fully integratable 1.55-μm wavelength continuously tunable asymmetric twin-waveguide distributed Bragg reflector laser

We demonstrate a single-frequency continuously tunable three-section distributed Bragg reflector laser operating at a center wavelength of /spl lambda//sub 0/=1.548 /spl mu/m using a fully integratable asymmetric twin-waveguide structure. A low-loss tapered mode transformer couples the light between the active waveguide, or gain region, and the passive ridge waveguide where the phase and grating tuning sections are located. The device has a threshold current of 50 mA and output power of nearly 13 mW, with a slope efficiency of 0.12 W/A and a tuning range of 4.8 nm under pulsed operation. An independent phase section is used to continuously tune the wavelength, thus avoiding mode hops. Using a delayed self-heterodyne technique, we determine the linewidth to be (146/spl plusmn/2) kHz.

Effect of band gap renormalization on threshold current and efficiency of a distributed Bragg reflector laser

The threshold current and the external efficiency of a three-section distributed Bragg reflector laser are investigated as a function of a forward electrical bias applied to the passive sections. Within a well-determined range, the threshold current increases and the external efficiency decreases with increasing bias. This effect is attributed to band gap renormalization.

Measurements of frequency responses of three-section distributed Bragg reflector lasers and application to modulation spectroscopy

The feasibility for wavelength modulation spectroscopy using a three-section distributed Bragg reflector (DBR) laser modulated at the phase section has been investigated. The FM and AM responses have been measured versus frequency from dc to 3 GHz at various positions on the tuning curve. The modulation efficiency as a function of the tuning currents combined with modulation frequency has been studied. In particular the behaviour at the positions of laser mode jumps has been emphasised as well as consistency of the recorded spectra across the entire tuning range. These tests were performed with a tuneable Fabry–Perot filter. The operation conditions were adapted for high and sustained FM response for modulation spectroscopy over a wide wavelength range. A conventional Bragg grating is used as an example of practical application.

Evaluation of distributed Bragg reflector lasers for high-sensitivity near-infrared gas analysis

Three-section distributed Bragg reflector (DBR) lasers emit- ting in the 1.5-mm wavelength region are characterized for use as a light source in a spectrometer for gas analysis. The three-section DBR lasers facilitate a wide, continuous tuning range while preserving the output power at a constant level. Typical characteristics for three-section DBR lasers and potentials and limitations of these lasers in gas-monitoring applications are discussed. A fiber optic system for high-sensitivity gas detection using wavelength-tunable DBR lasers is also presented. © 1997 Society of Photo-Optical Instrumentation Engineers.

Accessible tuning range of direct intensity modulated three-section DBR lasers in WDM applications

Wavelength division multiplexing (WDM) applications which require a few wavelengths can utilize the distinct longitudinal modes of a distributed Bragg reflector (DBR) laser for the wavelength multiplexing and a fiber Fabry-Perot optical filter for the wavelength demultiplexing. For direct intensity modulated DBR lasers, the portion of the CW mode tuning curve which yields reliable WDM system performance is determined based on measurements of the modulated mode suppression ratio and bit error ratio. For an optical filter with a bandwidth of 54.5 GHz, the portions of the CW mode tuning curves which yield a bit error ratio less than 10/sup -10/ vary from 0.7-0.85, depending on the particular longitudinal mode. The performance implications of the optical filter bandwidth and the influence of direct modulation on the laser spectrum are also examined.

Fast wavelength switching of three-section DBR lasers

For optical crossconnect and packet switched applications based on fast wavelength switching of distributed Bragg reflector (DBR) lasers, the wavelength switching delay is an important device characteristic. A large-signal model for a three-section DBR laser is described which permits evaluation of the intramodal and intermodal wavelength switching delay. The steady-state mode spectrum and loss obtained from a transmission line model of the laser are used in modified multimode rate equations to explicitly include the device structure and operating conditions in the dynamic model. Mode competition is shown to cause the intermodal wavelength switching delay to increase significantly as the destination wavelength approaches the edge of a mode tuning curve. The same behaviour is observed experimentally. >

Wavelength-independent output power from an injection-tunable DBR laser

Injection-tunable three-section distributed Bragg reflector lasers emitting near 1.55 μm have been fabricated employing bulk 1.48-μm-bandgap InGaAsP in the tuning layer of the phase and Bragg sections. The gain in this material compensates for the increased absorption loss during tuning, which results in a nearly wavelength-independent optical output power. The maximum obtained output power is 28 mW ex facet, with a spectral linewidth around 5 MHz.

Influence of mode competition on the fast wavelength switching of three-section DBR lasers

For a three-section distributed Bragg reflector (DBR) laser, the dependence of the intermodal wavelength-switching time on the precise wavelengths within two longitudinal modes is examined experimentally and theoretically. When switching from a fixed wavelength in the central region of the tuning curve for one mode to a second wavelength on the tuning curve for another mode, a significant variation of the switching delay occurs as the second wavelength spans the mode tuning curve. Mode competition is identified as being responsible for this variation. >

Wide continuous wavelength tuning of a narrow linewidth DBR laser

A continuous wavelength tuning range of 5.4 nm is obtained for a three-section DBR (distributed Bragg reflector) laser by applying one control current in both forward and reverse bias directions. In the reverse direction no significant linewidth broadening is seen due to the absence of injection-recombination shot noise, and a linewidth of less than 3 MHz is obtained over a wavelength span of 1.8 nm. The minimum linewidth observed is 580 kHZ. >

Wavelength tuning analysis and spectral characteristics of three-section DBR lasers

A theoretical model for the design of three-section distributed Bragg reflector (DBR) lasers using the transfer matrix method is presented. The oscillation parameters, the tuning behavior, and the linewidth are derived. The effect of a discontinuity of the waveguide at the active-passive interface is accounted for by using scattering matrix parameters, easily combined with the transfer matrix method. The influence of such an interface is studied and the importance of optical losses at this point is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

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.

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 mu m wavelength, which is in good agreement with the experimental results published thus far.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>