Gain-coupled Distributed Feedback Lasers Research Articles

Interferometric Optical Pumping of an InGaN/GaN-Based Gain-Coupled Distributed Feedback Multi Quantum Well Laser

We describe an all-optical method to achieve—prior to further advanced processing steps—a perfect match of the relevant wavelength-sensitive parameters of an InGaN/GaN semiconductor distributed feedback laser. Instead of permanently etching and epitaxially over-growing a waveguide-based diffraction grating for the definition of an index-coupled distributed feedback laser, we suggest here—by employing a powerful ultraviolet pump laser—a non-permanent, photoinduced generation of an optical diffraction grating. The resulting complex refractive index modulation then forms a gain-coupled distributed feedback laser. Such an approach has the advantage of remaining flexible as long as possible—both in terms of the correct grating period and the ideal coupling constant. This flexibility is maintained until the definitive etch and the epitaxial over-growth of the diffraction grating are completed. Such devices can—like their dye laser counterparts in the early seventies—also be used as ultra-broadly tunable single-mode sources.

Gain-coupled 770 nm DFB semiconductor laser based on surface grating

Single-longitudinal-mode gain-coupled distributed feedback (DFB) lasers based on high-order gain-coupled surface gratings emitting at 770 nm window are implemented. The periodic surface metal p-contact with insulated grating grooves realizes a gain coupled mechanism. Our devices provided a single longitudinal mode with the maximum CW output power up to 116.8 mW@400 mA with facet coated (HR>99%, AR<0.5%), 3 dB linewidth is 0.26 pm and SMSR is 36 dB. Due to easy-to-manufacture technology and stable performance, it provides a practical gain-coupled distributed feedback laser emitting at 770 nm region manufacturing method for commercial applications.

1045 nm purely gain coupled semiconductor laser based on periodic electric injection

Distributed feedback lasers near 1050 nm have many applications such as high resolution imaging in medical, production inspection and 3-D sensing. In this paper, we demonstrate a purely gain coupled distributed feedback laser based on periodic electric injection. By using simple fabrication process steps, the same as those for Fabry–Perot lasers except for periodic current injection windows, we realized lasing single longitude mode in F–P structure due to surface periodic electric injection only. The device operates with a single-mode CW output of 51.9-mW power at 250 mA. The slope efficiency is 0.24 W/A, and the side-mode suppression radio is greater than 35 dB. The spectra maintain good single-mode output characteristics over a tuning range greater than 3.48 nm within only 9 °C.

996 nm high-power single-longitudinal-mode tapered gain-coupled distributed feedback laser diodes.

A high-power single-longitudinal-mode regrowth-free tapered gain-coupled distributed feedback laser diode based on periodic current injection is achieved at 996 nm. It enhances the output power without beam quality degrading. A continuous-wave output power of over 1.12 W is achieved at 3 A. The maximum output power in single-longitudinal-mode operation is up to 0.56 W at 1.4 A. The power conversion efficiency is over 24%, and the slope efficiency is 0.58 W/A. The side mode suppression ratio is over 38 dB; the 3 dB spectral linewidth is less than 2.4 pm. The lateral far-field divergence angle is only 14.98°, and the beam quality factor M2 is 1.64, achieving a near-diffraction-limit emission. Our device has great potential in commercial applications and the experimental study of high-power near-diffraction-limit laser diodes for its low-cost fabrication technique and narrowband single-longitudinal-mode emission at high power.

Narrow-Strip 670 nm Gain-Coupled Distributed Feedback Laser Based on Periodic Anodes Fabricated by I-Line Lithography

A narrow-strip single-longitudinal-mode gain-coupled distributed feedback semiconductor laser with a central wavelength of approximately 670 nm is demonstrated. We fabricate a novel micro-scale regrowth-free gain-coupled grating with an island-like shape without nanoscale gratings by i-line lithography only. The maximum output power from the fiber of the device with butterfly package is 48.1 mW at 100 mA and its slope efficiency is 0.79 W/A. The laser can be continuously tuned from 670.750 to 670.784 nm with a side-mode suppression ratio of over 40 dB, covering the absorptive peak of lithium atoms. Our easily fabricated devices have great potential as light sources in many applications such as lithium atom detectors.

990 nm High-Power High-Beam-Quality DFB Laser With Narrow Linewidth Controlled by Gain-Coupled Effect

High-power single-longitudinal-mode regrowth-free gain-coupled distributed feedback laser diode based on ridge waveguide with periodic current injection is achieved at 990 nm. Our device is fabricated only by standard i-line lithography with micron-scale precision, obtains an excellent performance at high injection current. A continuous-wave power of over 0.681 W is achieved at 3 A. The maximum continuous-wave power at single-longitudinal-mode operation is up to 0.303 W at 1.4 A. Narrow linewidth emission has been reached with a 3 dB spectrum width less than 1.41 pm. The high side mode suppression ratio is over 35 dB. The lateral far field divergence angle is only 15.05°, the beam quality factor M 2 is 1.245, achieving a laterally near-diffraction-limit emission. It is more beneficial for single-mode fiber coupling as pumping sources and other applications which require high beam quality at high power with easy fabrication technique.

Two-Segment Gain-Coupled Distributed Feedback Laser

A two-segment regrowth-free gain-coupled distributed feedback (DFB) laser monolithically integrated different gain contrast segments was proposed, realizing both wavelength-tunable (5 nm) and wavelength stabilization characteristics, controlled by a single electrode only. At current larger than 320 mA, side mode suppression ratio reached >30 dB with 3 dB linewidth μ m-width ridge were patterned merely by one-step i-line lithography. It provides a novel method for low-cost practical gain-coupled DFB laser fabrication, which can be used in either/both wavelength-tunable applications such as sensing and detection, or/and wavelength stabilization fields such as pumping fiber lasers.

Theorical analysis of a monolithic all-active three-section semiconductor laser

We propose a novel semiconductor laser structure. It is composed of three cascaded active sections: a Fabry-Pérot laser section sandwiched between two gain-coupled distributed feedback (DFB) laser sections. We have modeled this multi-section structure. The simulation results show that compared with index- and gain-coupled DFB lasers, a significant reduction in the longitudinal spatial-hole burning can be obtained with the proposed device, and that this leads to a stable single longitudinal mode operation at relatively high optical power with a SMSR exceeding 56dB. Full Text: PDF ReferencesL.A. Coldren, "Monolithic tunable diode lasers", IEEE J. Select. Topics Quant. Electron. 6, 988 (2000) CrossRef O. Kjebon, R. Schatz, S. Lourdudoss, S. Nilsson, B. Stalnacke, L. Backbom, "30 GHz direct modulation bandwidth in detuned loaded InGaAsP DBR lasers at 1.55 [micro sign]m wavelength", Electron. Lett. 33(6), 488 (1997). CrossRef N. Kim, J. Shin, E. Sim, C.W. Lee, D.-S. Yee, M.Y. Jeon, Y. Jang, K.H. Park, "Monolithic dual-mode distributed feedback semiconductor laser for tunable continuous-wave terahertz generation", Opt. Expr. 17(16), 13851 (2009). CrossRef M.J. Wallace, R. ORreilly Meehan, R.R Enright, F. Bello, D. Mccloskey, B. Barabadi, E.N. Wang, J.F. Donegan, "Athermal operation of multi-section slotted tunable lasers", Opt. Expr. 25(13), 14426 (2017). CrossRef J.E. Carroll, J.E.A. Whiteaway, R.G.S. Plumb, "Distributed Feedback Semiconductor Lasers", Distributed feedback semiconductor lasers (IEE and SPIE, 1998). CrossRef H. Ghafour-Shiraz, Distributed Feedback Laser Diodes and Optical Tunable Filters (Wiley, 2003). CrossRef D.D. Marcenac, Ph.D dissertation (University of Cambridge, 1993). DirectLink L.M. Zhang, J.E. Carroll, C. Tsang, "Dynamic response of the gain-coupled DFB laser", IEEE J. Quant. Electr. 29, 1722 (1993). CrossRef W. Li, W.-P. Huang, X. Li, J. Hong, "Multiwavelength gain-coupled DFB laser cascade: design modeling and simulation", IEEE J. Quant. Electro. 36(10), 1110 (2000). CrossRef B.M. Mehdi, H. Rachid, in Proc. 3rd Intern. Conf. on Embedded Systems in Telecomm. and Instrument., Annaba, Algeria (2016). DirectLinkC. Henry, "Theory of the linewidth of semiconductor lasers", IEEE J.Quant. Electr. QE-18, 259 (1982). CrossRef K. Takaki, T. Kise, K. Maruyama, N. Yamanaka, M. Funabashi, A. Kasukawa, "Reduced linewidth re-broadening by suppressing longitudinal spatial hole burning in high-power 1.55-/spl mu/m continuous-wave distributed-feedback (CW-DFB) laser diodes", IEEE J. Quant. Electr. 39, 1060 (2003) CrossRef

Study of gain-coupled distributed feedback laser based on high order surface gain-coupled gratings

Single-longitudinal-mode, gain-coupled distributed feedback (DFB) lasers based on high order surface gain-coupled gratings are achieved. Periodic surface metal p-contacts with insulated grooves realize gain-coupled mechanism. To enhance gain contrast in the quantum wells without the introduction of effective index-coupled effect, groove length and depth were well designed. Our devices provided a single longitudinal mode with the maximum CW output power up to 48.8 mW/facet at 971.31 nm at 250 mA without facet coating, 3dB linewidth (<3.2 pm) and SMSR (>39 dB). Optical bistable characteristic was observed with a threshold current difference. Experimentally, devices with different cavity lengths were contrasted on power–current and spectrum characteristics. Due to easy fabrication technique and stable performance, it provides a method of fabricating practical gain-coupled distributed feedback lasers for commercial applications.

Gain-coupled distributed feedback laser based on periodic surface anode canals

A single-longitude-mode, broad-stripe, gain-coupled, distributed-feedback laser based on periodic surface anode canals (PSACs) is demonstrated. The PSACs, produced by i-line lithography, enhance the contrast of periodic current density in the active layer without introducing effective photon coupling; calculated grating κL is only 0.026. Power of 144.6mW at 968.8nm, with spectrum linewidth less than 0.04nm on every uncoated cleavage facet, is obtained at a current of 1.2A with a side-mode suppression ratio >29 dB.

Dependence of coupling coefficient and lasing wavelength on injection current in pure gain-coupled distributed feedback semiconductor lasers

A theoretical analysis of purely gain-coupled distributed feedback lasers (PGC-DFB) with antireflection facets is given. The effects of longitudinal non-uniformity of photon and carrier density above a threshold circumstance are considered. In addition, the influence of carrier-induced refractive index change on the coupling coefficient of the PGC-DFB structure is assumed. It is shown that the coupling coefficient in this structure varies with injected current and it gets a real part or an index coupled term. As a result the normalized coupling coefficient, κL, becomes a complex number. So, above the threshold condition, the PGC-DFB laser operates like a complex coupled one. Variation of the oscillation wavelength and the threshold gain of the PGC-DFB laser in terms of current is analyzed too. Numerical analysis shows that this structure has wavelength tunability with respect to current. The theoretical model is based on the self-consistent solution of coupled wave equations and the carrier rate equation by the transfer matrix method.

1.3 µm gain coupled DFB laser with InGaAlAs MQW grown on absorptive InGaAsP corrugation

An InGaAlAs multiquantum well (MQW) has been successfully overgrown on the absorptive InGaAsP corrugation for fabricating the 1.3 µm gain coupled distributed feedback (DFB) lasers. The absorptive InGaAsP corrugation was efficaciously preserved during the overgrowth of the InGaAlAs MQW active region. The absorptive InGaAsP corrugation has a relatively high intensity around the PL peak wavelength in comparison with that of the InGaAlAs MQW. The fabricated DFB laser exhibited a side mode suppression ratio of 40 dB together with a high single-mode yield of 90%.

One-dimensional aligned InAs/InP quantum dots chain growth by metalorganic vapor phase epitaxy for 1.55 μm application

We report one-dimensional aligned growth of InAs quantum dots (QDs) in a dielectric grating on InP (0 0 1) by metalorganic vapor phase epitaxy (MOVPE). InAs QDs were grown selectively along the edge of the SiO 2 stripes to form dual chains in each period of the grating formed by laser holography method with a period of 244 nm. The linear alignment property of InAs dots was maintained in wet chemical etched SiO 2 array template with 1.7 μm openings. The InAs QDs grown in SiO 2 grating template showed room temperature photoluminescence (PL) emission around 1.5 μm, red shifted from QDs grown on plain InP substrate. The results can be applied to naturally gain coupled distributed feedback lasers and coupled QDs growth.

Injection locked multi-section gain-coupled dual mode DFB laser for terahertz generation

A dual mode multi-section gain-coupled distributed feedback laser with tunable mode spacing is subharmonically injection locked at 0.315 THz. The injected signal consists of an optical comb with harmonics 35 GHz apart and a bandwidth of approximately 1.9 THz. The optical comb is a result of strong four-wave mixing in a highly-nonlinear dispersion-shifted fiber. In order to observe locking of the multi-section laser, the output is optically downconverted to RF frequencies using the same optical comb. The locked multi-section DFB laser is a coherent and tunable optical source suitable for continuous-wave terahertz generation systems.

Tunable Infrared Semiconductor Lasers Based on Electromagnetically Induced Optical Defects

We propose tunable midinfrared laser systems based on dynamic formation of electromagnetically induced optical defect sites. Such defects occur in a waveguide structure having a uniformly corrugated quantum well structure in the absence of any structural defect or phase slip. In the absence of a control laser field, such a corrugated structure causes a uniform perturbation of refractive index along the waveguide. However, when a relatively small region of such a waveguide structure is illuminated from the side by the control laser field, electromagnetically induced transparency occurs in this region while its refractive index corrugation is removed. We also show that such a coherently induced defect can be dynamically moved along the waveguide structure by just steering the control laser beam to illuminate different locations. We utilize the fact that the phase associated with this defect site can be adjusted via changing the length of the illuminated region to present a tunable distributed feedback laser where its lasing wavelength can be continuously varied within the stop-band. We study the case where two coherently induced defect sites happen along the waveguide structure and discuss the impacts of illumination of the whole waveguide structure with the control laser field. We show that the latter can either make the waveguide coherently transparent by destroying its refractive index perturbation and stop-band, or generate a gain-without-inversion grating. Formation of such a grating allows the waveguide to act as a tunable partly gain-coupled distributed feedback laser.

Purely gain-coupled distributed feedback laser via a bright optical lattice

We utilize degeneracy of Bragg resonance and the intersubband transitions in a quantum well bright optical lattice to propose a coherently induced purely gain-coupled distributed feedback laser. The optical lattice is generated via formation of periodic regions of resonant intersubband gain without inversion in the absence of any refractive index perturbation using a control laser field. We show that longitudinal mode intensity profile and standing wave effects of such an intrinsically single-mode intersubband laser can be coherently controlled. These features allow immunity against spatial hole burning and lasing when modal loss is higher than modal gain.

Electromagnetically induced distributed feedback intersubband lasers

We propose a method to coherently generate uniform and phase-shifted complex-coupled (CC) semiconductor distributed feedback (DFB) lasers based on intersubband transitions in n-doped quantum-well structures. This is done by utilizing infrared-induced coherent optical processes in these structures including resonant enhancement of refractive index of the conduction intersubband transitions and generation of laser-induced transparency and gain without inversion. We show that these coherent phenomena can generate electromagnetically induced gratings where the index and gain/loss perturbations and their relative phases can be manipulated using an infrared laser beam. This allows us to coherently control optical feedback in a waveguide structure, switching from a case where there is no feedback in the absence of the infrared laser to the case where different types of CC optical feedbacks are generated as this field is properly adjusted. These include generation of gain and index perturbations (partly gain-coupled DFB laser), pure index corrugation (index-coupled DFB laser), and loss and index perturbations (loss-coupled DFB laser). We study these feedback mechanisms in the cases where the optically induced gratings are uniform along the cavity or have a /spl pi//2 phase shift. We discuss mode characteristics of such electromagnetically induced DFB intersubband lasers and find out how here the gain- and index-coupled DFB lasers are associated, respectively, with gain without inversion and laser-induced transparency in the conduction intersubband transitions of quantum-well structures.

Optical microwave/millimeter-wave links using direct modulation of two-section gain-coupled DFB lasers

Transmission of 155-Mb/s binary phase-shift-keying-modulated microwave/millimeter-wave (MMW) signal on an optical carrier over up to 80 km of standard single-mode fiber has been demonstrated experimentally using direct modulation of a two-section gain-coupled distributed feedback laser. Direct data modulation at an MMW carrier frequency of 25 GHz was enabled by on-chip optical injection locking.

Nonlinear emission from an InGaAs/AlGaAs quantum-wire array

Gain-coupled distributed-feedback (GC-DFB) effects in a V-grooveIn0.2Ga0.8As/Al0.2Ga0.8As quantum-wire (QWR) array are investigated by comparison with those in aGaAs/Al0.2Ga0.8As QWR array. Temperature-dependent photoluminescence (PL) spectra are measured forboth samples, showing that the PL spectra from the QWRs are much stronger than thosefrom the quantum wells (QWs) in the entire temperature region. Then, InGaAs/AlGaAsQWR GC-DFB lasers are fabricated by one-step metallorganic chemical vapour deposition(MOCVD) growth and characterized. As a result, strong nonlinearity in the emissionspectra by optical feedback along the DFB directions is clearly observed near the thresholdcurrent, indicating that a V-groove InGaAs QWR array is a good candidate for again-coupled DFB laser.

180-GHz clock recovery using a multisection gain-coupled distributed feedback laser

All-optical clock recovery from 180-Gb/s data streams has been demonstrated using a self-pulsing multisection gain-coupled distributed feedback laser. The laser produces self-pulsations with a tuning range of more than 230 GHz. The recovered clock has a jitter of less than 410 fs over a dynamic range of 7 dB.