A widely tunable SOA-integrated DBR laser by combination of sampled and superstructure gratings

We report on the development of the first 30 nm tunable laser diode utilizing a front sampled grating-distributed Bragg reflector (SG-DBR) and a rear superstructure grating DBR (SSG-DBR). A high output power greater than 18 mW was achieved with superior longitudinal mode stability, as well as an overall power variation of less than 3 dB for the well-defined laser. Furthermore, lasers integrated with a semiconductor optical amplifier (SOA) enabled the output power to be controlled independently both by the active current and the SOA current, as well as achieving a maximum output power of 45 mW. The side-mode suppression ratio was in excess of 40 dB for all the 50 GHz spaced wavelength channels.     

40-GHz dual-mode-locked widely tunable sampled-grating DBR laser

Generation of 40-GHz alternate-phase pulses is demonstrated using a dual-mode-locked sampled-grating distributed Bragg reflector laser. More than 10-dB extinction and >20-dB sidemode suppression ratio is measured over the >40-nm tuning range of the laser. Based on captured phase noise spectra, the timing jitter is estimated in the 0.35-0.41-ps range. The demonstrated dual-mode laser would form an attractive basis for an integrated 40-Gb/s return-to-zero transmitter.     

The side-mode-suppression ratio of a tunable DBR laser

The authors investigate, both experimentally and theoretically, how the side-mode-suppression ratio (SMSR) of a multisection multiple-quantum-well distributed-Bragg-reflector (MQW-DBR) laser varies with tuning current. It is found that as the tuning current is adjusted the wavelength and the SMSR vary, with the peak SMSR=43 dB. The output power also varies with tuning current, and one can find when the laser is near a mode hop by examination of the light versus tuning current curve. This implies that the tuning current can be adjusted so that the laser frequency is near the center of the Bragg band without measuring the SMSR. The measurement are in good agreement with theory     

Widely tunable sampled grating DBR laser with integratedelectroabsorption modulator

We report on the development of the first widely tunable semiconductor laser with an integrated electroabsorption modulator. The laser is a four-section buried-ridge sampled-grating distributed Bragg reflector design. It has a 41-nm continuous tuning range with a maximum tuning current of 23.5 mA for the hack mirror and 21 mA for the front mirror. The modulator is based on a 0.87-eV bandgap bulk waveguide structure. It is capable of producing more than 22 dB of optical extinction over the entire tuning range of the laser with a -4.0-V bias     

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     

Frequency stabilization of tunable DBR laser using multiwavelengthlight injection locking technique

This paper proposes a frequency stabilization scheme for tunable three-section DBR laser diodes (3S-DBR LD) that use multiwavelength light injection locking. The oscillating wavelength of the SS-DBR LD is discretely switched between cavity modes when the injection current into DBR section is changed, and locked to one wavelength of the multiwavelength light injected from the DBR section facet under the injection locking condition. The light injection properties of the capture range and the relationships of relaxation oscillation versus input power and detuning are investigated experimentally. Injection locking on the multistate wavelength of a tunable DBR LD is performed using a two wavelength multiplexed light. As a result, we demonstrate 1 GHz capture range and more than 26 dB rejection ratio for the multiplexed injected light     

Fast wavelength switching and simultaneous FSK modulation using tunable DBR laser

The authors describe the operation of a tunable three-section DBR laser for multiwavelength switching with up to 48 resolvable wavelengths. Fast switching among wavelengths that are spaced over a 2.2 nm continuous tuning range and simultaneous FSK data modulation of each channel are demonstrated. A novel wide-deviation FSK modulation scheme to reduce temperature induced wavelength drifts is also described.<>     

Simultaneous fast wavelength switching and intensity modulationusing a tunable DBR laser

The use of a three-section distributed Bragg reflector (DBR) laser to switch wavelengths rapidly and simultaneously transmit data by intensity modulation is discussed. This combination simulates the operation of a tunable transmitter in a multiwavelength packet switch. In this type of switch, each output port is tuned to receive data on a unique, fixed wavelength; packets are routed from input ports to the appropriate output ports by wavelength addressing. In each transmission cycle, the input port transmitter tunes to the wavelength associated with the intended output port and subsequently broadcasts the data packet. Limitations on various system parameters, such as the number of allowed channels, the wavelength switching times, and packet lengths (residency times), as determined by thermally-induced wavelength drifts are also discussed. The advantages of using a single device for both fast wavelength switching and direct data modulation are significant: the elimination of external modulators improves both the simplicity of the implementation and the available power budget     

单片集成倾斜SOA的宽可调谐取样光栅分布布拉格反射激光器

高功率和宽调谐范围的单片集成倾斜SOA的宽可调谐取样光栅分布布拉格反射激光器被成功制备。倾斜的SOA结构和端面增透膜有效的降低了端面的反射率。器件调谐范围大于38nm,波长覆盖较好,调谐范围内波长输出功率均大于9mW。     

Monolithic integration of widely tunable sampled grating DBR laser with tilted semiconductor optical amplifier

High output powers and wide range tuning have been achieved in a sampled grating distributed Bragg reflector laser with an integrated semiconductor optical amplifier. Tilted amplifier and anti-reflection facet coating are used to suppress reflection. We have demonstrated sampled grating DBR laser with a tuning range over 38 nm, good wavelength coverage and peak output powers of more than 9 mW for all wavelengths.     

Dual-wavelength DBR fiber laser

Stable continuous-wave lasing of two longitudinal modes of a distributed Bragg reflector fiber laser is reported. Intensity noise and coupling between the modes was characterized for both 0.8- and 0.2-nm mode separations.     

A tunable emerald laser

Emerald is a new broadly wavelength-tunable vibronic laser material with stimulated emission in the red to infrared due to⁴T_{2} rightarrow⁴Atransitions of Cr³⁺. Emerald has gain from 12 050 cm^-1to 14 000 cm^-1with high gain from about 12 300 cm^-1to 13 700 cm^-1. An emerald laser oscillator has been achieved, but has high losses.     

A tunable wavelength-conversion laser

A wavelength-conversion laser was fabricated using monolithic integration of a bistable laser diode and a wavelength-tunable distributed Bragg reflector (DBR) laser. This device converts an input light signal with a certain wavelength to output light with a tunable wavelength over 3.5 nm. Input power required for switching is investigated, and its resonant dependence on input wavelength is revealed. Input polarization is also discussed, and suppression of crosstalk is demonstrated. This device's turn-off switching response is greatly influenced by the light power of the input signal as well as bias current, and the first 1 Gb/s operation is achieved in optimum conditions for fast turn-off and stable turn-on     

可调谐紫翠宝石激光器

用三元石英双折射滤光片对紫翠宝石激光进行调谐,已得到从735.7～796.1nm间60.4nm的连续调谐输出。用LiF被动晶体Q开关工作时激光线宽约为0.001nm。调谐时输出能量无明显下降,振荡阈值只增加了5％。     

Strongly sub-Poissonian electrical noise in 1.55-/spl mu/m DBR tunable laser diodes

We report terminal electrical noise measurements on 1.55-/spl mu/m DBR tunable laser diodes in the 1 Hz-1 MHz frequency range, performed using an electrical correlation method. These measurements are compared with a comprehensive electrical model based on rate equation formalism. Taking into account diffusion phenomenon and structural parameters, we obtain a complete agreement between the model and the measurements above threshold and a quite similar tendency below threshold. The influence of Bragg section bias is also discussed.     

Method for setting the absolute frequency of a tunable, 1.5 μmtwo-section DBR laser

A technique for setting the absolute frequency of a 1.5-μm two-section distributed Bragg reflector (DBR) laser using an Er:YAG optical filter as a frequency discriminator is described. The absolute frequency of the laser was controlled with an accuracy better than 300 MHz over a tuning range of several hundred gigahertz. The frequency drift with laser temperature was -130 MHz/°C, and the tuning rate with current in the active region was 40 MHz/mA     

A tunable far infrared laser

A continuously tunable far infrared (FIR) laser has been demonstrated; experimental results are presented. A high-pressure (10-12 atm) continuously tunable CO2TE laser is used to pump Raman transitions in CH3F; the generation of continuously tunable radiation in the250-300 mum wavelength range is reported. Accurate frequency and bandwidth measurements have been made and the FIR bandwidth in superradiant emission isapprox4-5GHz. Consequently, the generation of frequency tunable, subnanosecond pulses in the FIR appears feasible. The generation of tunable laser radiation from 150 to 1000 μm by stimulated Raman scattering should be possible using higher pump intensity and/or other gases.     

Long wavelength MEMS tunable VCSEL with InP-InAlGaAs bottom DBR

In this letter, we present the first demonstration of a long wavelength-tunable vertical-cavity surface-emitting laser (VCSEL) using an InP-InAlGaAs distributed Bragg reflector (DBR). The use of such a DBR improves the thermal resistance of the VCSEL while keeping the growth process simple. The devices show operation to temperatures greater than 75/spl deg/C, and single-mode devices emit powers as high as 0.9 mW at room temperature. The tuning range is as high as 17 nm.     

Super-structure-grating (SSG) for broadly tunable DBR lasers

The reflection characteristics of super-structure-grating (SSG) reflectors are demonstrated theoretically and experimentally. The periodic multireflection peaks with high reflectivities of 68~98% are theoretically shown in the reflection spectrum. The experimental characteristics of a ridge-type SSG reflector are in good agreement with the theoretical design     

Dynamic responses of widely tunable sampled grating DBR lasers

The modulation bandwidth, dynamic mode suppression ratio, and wavelength chirp of directly modulated sampled grating DBR lasers have been measured. Although the tuning range can be up to an order of magnitude larger than in simple DBR lasers, the chirp is about the same or better over a wide range of operation parameters. The modulation bandwidth was in excess of 4 GHz and the dynamic MSR remained larger than 40 dB as long as the current did not swing below threshold. The linewidth enhancement factor was extracted from the measured chirp parameters and ranged from three to eight for different lasing wavelengths of the tunable lasers. The dispersion of the linewidth enhancement factor is consistent with published theoretical predictions.