Modulation response of a longcavity, gainlevered quantumdot semiconductor laser michael pochet,1, nicholas g. Modulation response of a longcavity, gain levered quantum. Using an external cavity semiconductor laser coupled to an additional empty cavity, optical pulses on the order of 100 ps duration at repetition rates of 12 ghz have been generated. Single frequency vertical external cavity surface emitting. Extraction of semiconductor laser rate equation parameters. Fine structure characteristics of semiconductor laser.
Chirp minimization and optimum biasing for currentmodulated coupledcavity semiconductor lasers. N the world of semiconductor lasers, coupled cavity lasers are of interest for two reasons. A simple theory is developed to obtain synchronization conditions and to analyze the effects of the. We present here a direct comparison of the continuous wave solutions and their stability properties, which are referred to in the lk model as the external cavity modes ecms and in the tw model as the compound cavity modes ccms. External cavity laser diodes ecls are lasers with a very small line width, very good wavelength stability, and very low noise. Coupled cavity effects in fm semiconductor lasers article pdf available in journal of lightwave technology 176. Design of external cavity semiconductor lasers to suppress wavelength shift and mode hopping l. Pdf mutual optical injection in coupled dbr laser pairs. With the progress of optical transmission technology, various kinds of semiconductor lasers have been developed for the application to wavelength division multiplexing, high speed, low power consumption, and photonic integration. Verticalexternalcavity surfaceemitting lasers and quantum dot lasers fig. Publishers pdf, also known as version of record includes final page, issue and volume numbers. There is a great variety of different semiconductor lasers, spanning wide parameter regions and many different application areas.
External cavity laser diodes fibrecoupled laser diodes. The laser cavity consists of a waveguide terminated on each end by a mirror. In addition, a laser diode contains an optical cavity where stimulated emission takes place. In our case the extended cavity is formed by the highlyreflecting rear facet of the diode and a dif fraction grating. This material comes in the form of ingots that are then further processed into substrates to which layers of other materials are added.
The laser cavity of length l d, and front and back facet reflectivities of r f and r b, respectively, is coupled with an ultrashort external cavity of length l ex, refractive index n ex, and endmirror reflectivity r ex. Coupledcavity semiconductor lasers have the potential of offering mode selectivity together with wavelength tunability. Rp photonics encyclopedia semiconductor lasers, laser diodes. Vertical external cavity surface emitting lasers vecsels are a unique blend of both solid state and semiconductor lasers. Fabryperot fp, formed by the cleaved facets of the semiconductor material. Modehopfree tuning over 140 ghz of external cavity diode. A semiconductor laser diode consists of several parts. Metal contact ptype material active region ntype material ntype material metal contact from the picture one can see, that in principle you have the same structure like a diode where you. An interference filter is a multilayer thinfilm device. How semiconductor laser is made material, making, history. The output beam is assumed to travel several roundtrips in the external cavity due to.
Modulation performance of semiconductor laser coupled with. The semiconductor laser is very small in size and appearance. The frequency of the emitted light depends on the length of the optical cavity along the optical axis. In order to develop its theory, an im proved form of differential equations which describe the behavior of the external cavity semiconductor laser ecsl is needed. Laser structure and principle of operation laser diodes consist of a n diode with an active region where electrons and holes recombine p resulting in light emission. Widely tunable coupledcavity semiconductor laser article pdf available in applied optics 4819. Development of semiconductor laser for optical communication. Semiconductor laser diodes are no different in this respect.
Semiconductor lasers types, applications, construction. The discovery and continued development of the laser has revolutionized both science and industry. Since its invention in 1962, the semiconductor laser has come a long way. Frequency selectivity in laterally coupled semiconductor laser arrays. Jun 24, 2015 nonetheless, the inherent linewidth of semiconductor lasers, ultimately limited by the small size and quality factor q of the laser cavity, is typically in the mhz range, making the use of a. Modelocked vertical cavity semiconductor lasers by wenbin jiang inplane semiconductor lasers can be mode locked to generate ultrashort pulses, but the output power is small because of the gain saturation limitation. For some applications it is desirable to have a semiconductor laser whose wavelength can be tuned over a wide range, at least discretely. An easy demonstration is provided by the optics of semiconductor diode lasers. Extended cavity semiconductor laser an extended cavity semiconductor laser ecl is an arcoated laser diode ld coupled to a passive cavity. Fang abstract in this report, a model of external cavity semiconductor laser is built, and then based on this model a program is coded for simulating the thermally induced wavelength shift and mode hopping. We investigate experimentally the threshold and slope efficiency of a vertical cavity surface emitting semiconductor laser with halfwave spaced quantum wells as functions of the pump wavelength in the 700 900 nm. Vertical cavity surface emitting lasers vcsel, on the other hand, have a large gain saturation. Origin of diode laser astigmatism the nonuniformity of the gain profile along x has a focusing effect on the guided mode that is countered automatically by a divergent phase front imposed on the beam as it propagates along the zaxis of the cavity. Power efficiency of a semiconductor laser with an external cavity.
The development during the 1970s of gaas semiconductor lasers, emitting in the nearinfrared region of 0. Resonant optical pumping of verticalcavity semiconductor lasers. Nonlinear dynamics of two mutually injected externalcavity. Verticalexternalcavity surfaceemitting lasers and quantum. Scheme of a semiconductor laser with conventional optical feedback from an external cavity. Second, a coupled cavity laser makes a good model for a laser system in which there is optical feedback.
Pdf widely tunable coupledcavity semiconductor laser. Vertical cavity surface emitting lasers vcsel, on the other hand, have a. An externalcavity diode laser is a diode laser based on a laser diode chip which typically has one end antireflection coated, and the laser resonator is completed with, e. Widely wavelength switchable vcoupledcavity semiconductor. Semiconductor laser fundamentals major disadvantages of leds. For example, if the laser output is being cou pled into an optical fiber, any stray reflection back into. Narrowbanded ecl lasers are characterized by a very small line width, low noise, and very good wavelength stability. Small edgeemitting laser diodes generate a few milliwatts or up to 0. Only the photons that leave the cavity from the mirrors constitute useful output. T present, the external cavity semiconductor laser is a feasible means to realize a singlefrequency semi conductor laser. Coupled cavity semiconductor lasers have the potential of offering mode selectivity together with wavelength tunability.
They are used in optical communication and fibre sensor technology. Most semiconductor lasers are laser diodes, which are pumped with an electrical current in a region where an ndoped and a pdoped semiconductor material meet. Pdf record performance of electrical injection subwavelength. Dashed lines indicate threshold gains of the indi vidual lasers in the absence of coupling. Lester3 1department of electrical and computer engineering, us air force institute of technology, wrightpatterson air. Widely tunable semiconductor lasers have been in creasingly demanded in long haul, metropolitan, and access networks. Dynamics of a semiconductor laser with two external cavities. Pdf coupledcavity effects in fm semiconductor lasers. We have shown that dynamical states of the laser with one external cavity.
The mode of operation is somewhat di erent than that of the laser described in the previous chapter. Space diagram of semiconductor laser with two external cavities in space of ratios of their round trip times and pump parameter. Osa wavelength switchable semiconductor laser using half. A path to highpower, quality beam and uv using diode laser pumping, lowpower 10mw cw operation was demonstrated with gaas vcsel lasers 33. We study the synchronization of two unidirectionally coupled singlemode external cavity semiconductor lasers, that operate in a chaotic regime. A semiconductor laser diode is a device capable of producing a lasing action by applying a potential difference across a modified pnjunction. Laterally coupledcavity semiconductor lasers caltech authors.
Eigenfrequencies and the relative phases and amplitudes of the lasers are obtained from a weakcoupling model. Modulation performance of semiconductor laser coupled with an. The semiconductor material is designed to emit and absorb desirable wavelengths. This modified pnjunction is heavily doped and contained within a cavity thus providing the gain medium for the laser. I n the world of semiconductor lasers, coupledcavity. Pdf evolutionary optimization of nonperiodic coupled. One part is fed back into the original laser by the external mirror to complete the optical feedback loop, and the other part is injected into the other laser to form the mutual coupling bs em ld2 ld1 i 1 i 2 figure 1. Pdf mode locking of semiconductor lasers in a coupled. Nonlinear dynamics of two mutually injected external. May 01, 2000 the intracavity reflection couples the shorter laser cavity with a length of l7 to the longer laser cavity with a length of l. Dynamics and applications of delaycoupled semiconductors lasers. A semiconductor laser operated in an external cavity, which is built by a remote mirror or grating, is shown in fig. It is similar to a transistor and has the operation like led but the output beam has the characteristics of laser light. N the world of semiconductor lasers, coupledcavity lasers are of interest for two reasons.
Criteria for synchronization of coupled chaotic external cavity semiconductor lasers article pdf available in ieee photonics technology letters 142. A new semiconductor laser structure with digitally switchable wavelength is proposed. Modehopfree tuning over 140 ghz of external cavity diode lasers without antireflection coating sourav dutta, 1, d. Intermodal stability of a coupledcavity semiconductor laser. We also need expressions for the light coming out of the laser. Recently, a simple and compact v coupled cavity semiconductor laser has been proposed 17, and singleelectrode controlled wide wavelength tuning was demonstrated in the 1. Pdf we demonstrate a continuous wave cw subwavelength metalliccavity semiconductor laser with electrical injection at room temperature rt. The intracavity reflection couples the shorter laser cavity with a length of l7 to the longer laser cavity with a length of l. Improved rate equations for external cavity semiconductor. Laterally coupledcavity semiconductor lasers 397 fig. Threshold gain in the y, y2 plane for an lc2 laser consisting of two segments of lengths 200 and 240 pm and intercavity coupling coef ficient k 10 cm. The external cavity diode laser ecdl uses the ld chip as gain element and external reflectors as cavity mirrors, instead of the cleaved facets of ld chip. June 1989 improved rate equations for external cavity semiconductor lasers hui rongqing and ta0 shangping abstracta set of improved langevin rate equations for external r. The unique external cavity gives this laser the ability to define the laser mode and utilise intracavity elements for several.
Home proceedings volume 1583 article translator disclaimer. The output of each laser is split into two parts by the beam splitter. Extendedcavity semiconductor laser an extendedcavity semiconductor laser ecl is an arcoated laser diode ld coupled to a passive cavity. An external cavity diode laser is a diode laser based on a laser diode chip which typically has one end antireflection coated, and the laser resonator is completed with, e. External cavity modes in langkobayashi and traveling wave.
The timedelay treatment of ofb in semiconductor lasers is schematically shown in fig. Second, a coupledcavity laser makes a good model for a laser system in which there is optical feedback. Recently, a simple and compact vcoupled cavity semiconductor laser has been proposed 17, and singleelectrode controlled wide wavelength tuning was demonstrated in the 1. The material which often used in semiconductor laser is the gallium arsenide, therefore semiconductor laser is sometimes known as gallium arsenide laser. First, intention ally coupled lasers have been demonstrated to exhibit sin glelongitudinalmode oscillation under smallsignal modulation, fm modulation capabilities, and bistable op eration 11, 2. Coupled cavity dqw semiconductor lasers sciencedirect. However, there are also optically pumped semiconductor lasers, where carriers are generated by absorbed pump light, and quantum cascade lasers, where intraband transitions are utilized. Power efficiency of a semiconductor laser with an external. Semiconductor laser diodes of circular ring waveguide cavities showed attractive properties of their output characteristics and their potential applications in an optical control integrated system on a chip. Ultrafast nonlocal control of spontaneous emission eindhoven. This can be understood by looking at the following picture.
Output characteristics of a semiconductor laser diode with. Nonetheless, the inherent linewidth of semiconductor lasers, ultimately limited by the small size and quality factor q of the laser cavity, is typically in the mhz range, making the use of a. Advances in material purity and epitaxial growth techniques have led to a variety of semiconductor lasers covering a wide wavelength range of 0. Lester3 1department of electrical and computer engineering, us air force institute of technology, wrightpatterson air force base, ohio 45433,usa 2sensors directorate, us air force research laboratory, wrightpatterson air force base, ohio 45433. Fine structure characteristics of semiconductor laser diode. The approach used in this task was devised to systematically consider the influence of low frequency noise of semiconductor lasers, both experimentally and analytically, and then develop a model for the origin of the 1f noise in the laser spectrum. Modulation response of a long cavity, gainlevered quantumdot semiconductor laser michael pochet,1, nicholas g. The advent of miniaturized, semiconductor lasers has made this technology an integral part of. The cavity length can then be extended for a longer photon lifetime. Evolutionary optimization of nonperiodic coupledcavity semiconductor laser diodes. Schematic drawing of a laterally coupledcavity semiconductor laser.
Wavelength tuning was possible by changing the voltage of the ffp thus scanning the center frequency of the ffp over the period modes of the semiconductor fp cavity. Resonant optical pumping of verticalcavity semiconductor. The conventional semiconductor laser consists of a compound semiconductor, gallium arsenide. Describe how a semiconductor laser diode works a semiconductor laser diode consists of several parts.
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