Tunable photonic crystal coupled-cavity laser

We report the development of a tunable photonic crystal coupled-cavity laser diode based on InP. The laser consists of two photonic crystal channel waveguides that are coupled through a photonic crystal mirror segment in /spl Gamma/-M direction. The cavity lengths define the respective mode spacings in the cavities. The tuning characteristics of the device are compared with results obtained from a transfer matrix model. Quasi-continuous tuning is achieved in a 29.6-nm window with 36 wavelength division multiplexing channels spaced 0.8 nm apart (ITU grid). The simplicity of fabrication and promising output characteristics should make this tunable laser design an interesting source for monolithic integration into highly integrated photonic circuits.     

Dynamic single-frequency low-chirp operation of a laterally coupled waveguide (LCW) laser

Dynamic single-frequency operation of a laterally coupled waveguide (LCW) laser modulated at 1 GHz is reported for the first time. The device consists of three optically coupled but electrically separated resonators arranged side by side. By using two of the three coupled lasers as stabilising sources a resolution limited chirp of 0.022 nm has been achieved at a modulation depth of 85%.     

二种单频外腔式He－Ne激光器的自稳频原理再分析

作者用高气压加纵向非均匀磁场获得了二种单频、自稳频高输出功率的外腔式Ｈｅ－Ｎｅ激光器，１ｍ激光器的频率非稳定度为６．１７５×１０￣（－９）（τ≤１０ｓ）和３．３８×１０￣（－９）（τ≤１ｓ）；１．８ｍ激光器的频率非稳定度为１．１×１０￣（－８）（τ≤１ｓ）和２×１０￣（－８）（τ≤１０ｓ），所有数据由中国计量科学院测定。本文是继文献［１］，［８］，［９］和［１０］发表后，对这两种激光器的自稳频原理的再分析。     

二种单频外腔式He-Ne激光器的自稳频原理再分析

作者用高气压加纵向非均匀磁场获得了二种单频、自稳频高输出功率的外腔式He-Ne激光器,1m激光器的频率非稳定度为6.175×10-9(τ≤10s)和3.38×10-9(τ≤1s);1.8m激光器的频率非稳定度为1.1×10-8(τ≤1s)和2×10-8(τ≤10s),所有数据由中国计量科学院测定。本文是继文献[1],[8],[9]和[10]发表后,对这两种激光器的自稳频原理的再分析。     

Intermodal stability of a coupled-cavity semiconductor laser

We present an analysis of the steady-state operation of a two-element coupled-cavity laser near a mode hop. The equations of motion for the two cavities and two relevant modes of a longitudinally coupled-cavity laser are reduced to a system of nondimensional nonlinear ordinary differential equations which describe a general two-element laser. The equations are then solved and the stability of their solutions is analyzed. Depending upon the fill factors for the two modes, there exists an intrinsically multimode oscillation for operating conditions under which it was previously thought that no steady state existed. Under conditions where the multimode state is unstable, both of the single-mode states are stable with bistable transitions occurring only on the boundaries of the unstable multimode regimes.     

High-power single-frequency argon ion laser

Single-frequency oscillation has been obtained from an Ar laser of increased power level with the help of a three-mirror Smith reflector (power in the 4880-Å line was 2 watts). Equations and plots that permit the choice of optimum parameters of the three-mirror reflector are given. It is shown that for effective frequency selection in a high-power laser of great length it is necessary to use beam splitter reflectivities exceeding 0.5. Single-frequency lasers of this type may be used in holography.     

Actively stabilized single-frequency vertical-external-cavityAlGaAs laser

We report on actively stabilized single-frequency operation of a vertical-external-cavity surface-emitting semiconductor laser (VECSEL). The VECSEL was locked to a 300-MHz reference cavity allowing a relative frequency measurement that indicated a laser linewidth of 3 kHz. Coarse tuning over an 8.5-nm range was achieved, with fine tuning over 250 MHz. The laser produced up to 42 mW of output power in single-frequency operation     

Rate equation model of a coupled-cavity laser

We derive a novel rate equation system for a laser consisting of two coupled cavities arranged in tandem. The derivation of the photon rate equations is based on classical electromagnetic theory, while the rate equations for the electrons are written down heuristically in analog with the conventional laser rate equations. This paper discusses the initial numerical evaluation of our coupled-cavity laser model which indicates that the laser tends to oscillate more readily in a single longitudinal mode than a single-cavity laser of comparable length. The enhanced mode selectivity stems from the constructive and destructive interference of the fields in the two coupled cavities. Suppression of secondary longitudinal modes by more than 20 dB is readily obtainable. The coupled-cavity laser maintains single-wavelength operation even if the peak of the gain profile shifts over a certain wavelength range. However, when it finally responds to a sufficiently large shift of the gain profile, it does so by jumping discontinuously to a new (single) operating wavelength. Further investigations of frequency tuning by means of the injection current as well as studies of the frequency instability due to temperature and refractive index variations will be reported in a separate publication.     

自种子注入电光调Q单纵模激光器

为了研制出一台稳定的电光调Q单纵模激光器,采用快速电路主动控制腔内损耗,建立了准连续的预激光作为自注入种子,在此基础上进行电光调Q,再配合谐振反射器的选模作用,获得了稳定的高重频、大能量电光调Q单纵模脉冲输出,重复频率200Hz,最大单脉冲能量1．5mJ,能量抖动小于±2％;并获得了激光通过标准具的干涉图样。结果表明,长时间（大于1h）观察,激光器单纵模几率达100％。预激光技术可以获得高重频、大能量单纵模脉冲输出。     

The starting mechanism in coupled-cavity modelocked laser systems

We present what we believe to be the starting mechanism in coupled-cavity additive pulse modelocked (APM) laser systems. The etalon effect of the coupled cavity forces the main cavity to lase at two separate frequencies, thus producing short and strong mode beating “noise bursts” that can overcome dynamic gain saturation in large emission cross-section gain media. As a result, self-starting is possible for the NaCl:OH coupled-cavity color center laser. The dependence of the etalon effect on the cavity length detuning and its role in the dynamics of the APM process and in self-stabilized picosecond coupled-cavity lasers are discussed. The experimental observation of THz-mode beating fluctuations produced by the mode structure of a coupled-cavity NaCl:OH color center laser supports our model     

An experimental study on stable single-frequency semiconductorlasers with external cavity

Results are presented of a study on an external-cavity semiconductor laser consisting of a 1.3 μm buried-heterostructure laser diode with an antireflection coated facet and a 4 mm GRINROD. Due to its enclosed compact structure and strong optical feedback, it provides a stable single mode, with a mainside mode ratio of more than 30 dB, and is not sensitive to environmental perturbations. No mode jumping occurred during 12 h of continuous observation. The measured linewidth of 90 kHz is in good agreement with the newly developed theoretical calculation     

Stabilization of single frequency operation of coupled-cavity lasers

We present a theoretical analysis of cleaved coupled-cavity lasers. Mode selectivity arises from two mechanisms. The first is diffraction loss in the gap between the cleaved sections. The second is based on one section acting as a resonant reflector. Our analysis includes the change of refractive index with carrier density which shifts the cavity resonances and causes mode switching. Above threshold the gains g1and g2of the two cavities are not pinned, but are related for each mode in the form of a curve in the (g_{1}, g_{2}) plane. The separation of mode curves along a 45° line determines the ratio of mode intensities. Single mode operation above threshold is described by zones in the (C_{1}, C_{2}) plane where C1and C2are the currents driving the two cavities. Cases of stable, unstable, and bistable operation are discussed.     

Use of a simple external nonreciprocal attenuator in coupled-cavity TWT's

It is well known that use of a nonreciprocal sever in traveling-wave tube (TWT) design offers several advantages. Previous attempts to obtain these advantages involved incorporation of ferrite material within the envelope of helix TWT's. These attempts have encountered serious difficulties, and have had no apparent effect on TWT design practice. A different approach to realization of a nonreciprocal sever for a coupled cavity TWT is described. This approach involves readily available wave guide components external to the tube, and does not appear to require the solution of significant research and development problems. A computer simulation performed on the CTS 200 W TWT design indicates that a substantial improvement in efficiency could be obtained through use of this technique.     

Widely tunable single-frequency Er-doped fiber laser with longlinear cavity

A widely tunable single-frequency Er-doped fiber laser is demonstrated in a 21-m-long linear cavity incorporating all-fiber acoustooptic frequency shifters and a saturable absorption grating. Stable single-frequency operation is achieved with a sidemode suppression ratio higher than 50 dB and a wavelength tuning range greater than 40 nm     

Single-mode operation from an external cavity controlledvertical-cavity surface-emitting laser

Single-mode operation from an index-guided vertical-cavity surface-emitting laser (VCSEL) has been achieved by using a fiber Bragg grating (FBG) as an external selective wavelength reflector. The spectral characteristics of the external cavity controlled VCSEL under static and dynamic conditions have been studied. The FBG provided stable single mode operation under pseudorandom modulation with a sidemode suppression ratio of ~30 dB from 500 Mb/s up to 4 Gb/s at room temperature     

Dual-wavelength coupled-cavity Ti:sapphire laser with active mirrorfor enhanced red operation and efficient intracavity sum frequencygeneration at 459 nm

Sum frequency generation at 459 nm is demonstrated in a dual-wavelength coupled-cavity Ti:sapphire laser operating simultaneously at 808 nm and 1.06 μm. Enhanced operation of the Ti:sapphire laser at 1.06 μm is provided by a diode-pumped Nd:YAG active mirror. Comparable intracavity power is produced at both wavelengths, and 109 mW at 459 nm was generated with an intracavity KTP crystal. The 459-nm linewidth is 1 pm, and the conversion efficiency is 16%     

Wavelength-switchable single-frequency erbium-doped fiber ring laser

We demonstrate a single-frequency and wavelength-switchable fiber ring laser obtained by a Lyot filter used in combination with a sampled fiber Bragg grating and a saturable absorber. The operating wavelength of the laser can be tuned, with a constant 0.8-nm step, in the range 1552.6-1555.8 nm. The tuning mechanism works on the rotation of the polarization of Lyot filter input signal. The structure of the laser is very simple regarding its characteristics: an output power of 6 dBm, with a signal-to-noise ratio higher than 60 dB and a spectral linewidth of 8 kHz.     

可调谐单频掺镱光纤DBR激光器

对分布布拉格反射(DBR)的透射特性进行了分析,制作了一个单频窄线宽掺镱光纤DBR激光器.在977 nm半导体激光器泵浦下,在1052.5 nm波长处输出功率可达4 mW,线宽小于8 MHz(受测量仪器分辨率限制).采用弧形梁调谐光纤光栅,实现了DBR光纤激光器在单纵模工作状态下的连续调谐,调谐范围可达20.4 nm(1036.1～1056.5 nm),并研究了调谐对激光器的泵浦阈值和斜率效率的影响.     

An integrated coupled-cavity 16-wavelength digitally tunable laser

We present a digitally tunable laser that was realized by coupling two wavelength periodical four-channel lasers. The lasers were coupled with a multimode interference coupler, in such a way that the device has a common intracavity output waveguide containing the full multiplexed signal. In the two laser cavities, 1 /spl times/ 4 PHASARs were used with a channel spacing of 100 and 400 GHz, respectively. By coupling each PHASAR to four semiconductor optical amplifiers, 4 /spl times/ 4 channels were generated. The measured SMSR for each of the 16 wavelengths is better than 40 dB.     

保偏光纤饱和吸收体单频窄线宽光纤激光器

研制了一种基于保偏(PM)光纤可饱和吸收体结合光纤光栅Fabry-Perot(FBG F-P)标准具的单频窄线宽光纤激光器.该激光器以高增益掺Er3+光纤(EDF)作为增益介质,采用行波环形腔消除空间烧空效应,并结合FBG F-P标准具选模,实现激光器单频运转.用一段PM EDF作为可饱和吸收体抑制跳模,以获得高效、稳...