WO2003079507A2 - Diode laser a modulation directe et a commande de fluctuation de longueur d'ondes - Google Patents
Diode laser a modulation directe et a commande de fluctuation de longueur d'ondes Download PDFInfo
- Publication number
- WO2003079507A2 WO2003079507A2 PCT/GB2003/001185 GB0301185W WO03079507A2 WO 2003079507 A2 WO2003079507 A2 WO 2003079507A2 GB 0301185 W GB0301185 W GB 0301185W WO 03079507 A2 WO03079507 A2 WO 03079507A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- region
- phase
- modulation
- signal
- gain
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/0625—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in multi-section lasers
- H01S5/06255—Controlling the frequency of the radiation
- H01S5/06256—Controlling the frequency of the radiation with DBR-structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/0625—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in multi-section lasers
- H01S5/06251—Amplitude modulation
Definitions
- the present invention relates to the direct modulation of a laser diode for use in optical communication systems and, in particular, to a directly modulated laser diode source with integral control of the level of optical signal chirp.
- the distributed feedback (DFB) laser is widely used for optical fiber communication because of its superior optical performance, such as single mode operation, large side-mode suppression ratio, high power and temperature stability.
- Direct modulation through the variation of the laser diode's injection current is one of the means whereby electronic data is transferred onto the optical carrier.
- EA modulator In order to transmit data at 10 Gb/s or at even higher speeds over long distances of from 10 km up to thousands of km, external modulation of the light signal is commonly used because of the lower chirp imparted.
- MZI Mach-Zehnder interferometer
- EA electro-absorption
- the EA modulator is sometimes fabricated directly adjacent the DFB laser diode in a monolithic chip. The fabrication process of such integrated EA-DFB laser is extremely complicated.
- Push-pull modulation is normally implemented in a three-contact laser, where the end contacts are modulated in- phase and the centre contact has a compensation modulation applied in anti-phase such that variations in the mean carrier density are reduced.
- the centre contact of the push-pull modulated laser is biased with a constant current, and the end contacts are modulated in anti-phase so that the current to one end contact is increased while the current to the other end contact is decreased by an exactly equal amount.
- the symmetry of the modulation leads to the increase in electron density at one end being automatically compensated by changes in the electron density at the other end, irrespective of the bias or modulation level.
- multi-section laser devices have been proposed in the literature. These include devices whose various sections have different band gap energies and which are selected such that the device lasing wavelength is located in the overlap region of the gain spectra of the sections.
- the lasing wavelength By selecting the lasing wavelength to be in the overlap region of the gain spectra of the sections, use can made of the positive detuning in one section and negative detuning in the other section, by compensating for positive chirp in one with negative chirp in the other.
- the achievable wavelength range of zero chirp is quite limited.
- phase shifting section In other devices, a current or voltage phase shifter is utilised to balance refractive index variations for wavelength stabilisation.
- current phase shifter concepts only work well with single frequency sinusoidal signals. This leads to a problem when operating with square wave signals, as it is important to ensure that all frequency components of the signal are phase-shifted together in the two sections.
- the phase shifting section often comprises the same active layer as the gain section with the same band gap energy. Therefore, as the phase shifting section is kept below lasing threshold, it will be absorbing at the wavelength of the light emitted by the gain section and consequently the optical loss of the device will be high.
- a modulated semiconductor laser comprises: a gain region, in which optical radiation is amplified; a phase region, having a higher energy band gap than the gain region and thereby substantially transparent to the optical radiation; means for applying an RF modulation signal to the gain region; and, means for applying an RF modulation signal to the phase region, wherein the signal applied to the phase region causes a phase modulation which compensates for wavelength variations in the optical radiation caused by the direct modulation of the gain region.
- the higher energy band gap of the phase region ensures that optical loss in this region is automatically low at the lasing wavelength without the need to actively drive the region to achieve transparency.
- the higher energy band gap of this region may be obtained by a number of techniques, including growth and regrowth, selective area epitaxy and quantum well intermixing (QWI).
- the laser comprises means for deriving the modulation signal to the gain region and the modulation signal to the phase region from a common RF modulation signal.
- the laser may comprise means to time differentiate the RF modulation signal to the gain region in order to derive the RF modulation signal to the phase region.
- the laser may further comprise means to invert the RF signal to the gain region in order to derive the RF signal to the phase region.
- the phase region includes a Distributed Bragg Reflector grating.
- a distributed grating structure provides additional wavelength selectivity.
- a semiconductor laser which further comprises: a first region having a Distributed Feedback Structure; and a second region having a Distributed Feedback Structure, wherein the gain region and the phase region are located between the first and second regions.
- the distributed feedback structures can provide alternative or additional feedback to discrete feedback from the device facets.
- a method of compensating for chirp in a directly modulated semiconductor laser comprises the steps of: providing a gain region of the semiconductor laser for amplification of optical radiation; providing a phase region having a higher energy band gap than the gain region and thereby substantially transparent to the optical radiation; applying an amplitude modulated RF signal to the gain region; and applying an amplitude modulated RF signal to the phase region, wherein the signal applied to the phase region causes a phase modulation of the light which compensates for wavelength variations in the optical radiation caused by the direct modulation of the gain region.
- the present invention applies a new chirp compensating technology to realise a zero-chirp or controlled low-chirp laser diode suitable for 10 Gb/s direct modulation.
- the present invention employs both a new laser diode structure and a new driving configuration, in comparison with prior art sources.
- Figure 1 shows a schematic of a two-section diode laser according to the present invention
- Figure 2 shows the variation in time of the wavelength shift and photon density associated with the diode laser of Figure 1 ;
- Figure 3 shows a schematic of a four-section diode laser according to the present invention.
- FIG. 1 shows a first embodiment of the proposed low-chirp laser diode, including a schematic of the RF driving arrangement.
- the laser is constructed from two parts: a gain region (part-A) with an bandgap energy that determines the emission wavelength and which does not contain a grating, and a distributed Bragg reflector (DBR) region (part-B), which has a higher energy bandgap than the gain region and also contains a diffractive grating structure within the waveguide.
- the higher energy bandgap means that the DBR region is practically transparent to the emitted laser light.
- the higher bandgap region can be implemented by growth and regrowth, selective area epitaxy or by quantum well intermixing.
- the gain region is driven by a radio frequency (RF) modulation signal
- the DBR region is driven by a signal comprising a DC component and a component derived from the RF signal.
- the component synthesized from the RF signal may comprise a direct copy of the RF signal, the time differential of the RF signal, dfdt(RF), the inverse-RF signal, and the time differential of the inverse-RF signal, cf/cff(inverse-RF).
- the operation of the proposed laser diode structure of Figure 1 is described as follows.
- a time-varying (RF) voltage is applied to the gain region (Part A)
- the amplitude (or intensity) of the light is modulated.
- the phase of the light is also modulated through an associated refractive index variation.
- a variation of the emission wavelength occurs, which is proportional to the time differential of the phase change resulting from the refractive index variation, as shown in Figure 2. Consequently, by modulating the drive current of the DBR region (Part-B), the emission wavelength of the light can similarly be modulated.
- the wavelength shift (chirp) from the gain region can be compensated, thus realising a chirp controllable laser diode.
- this permits compensation of the chirp over all frequency components of more complex (non-sinusoidal) signals, including square wave signals, which are widely used for digital encoding.
- Figure 3 shows a second embodiment of a low chirp laser in accordance with the present invention, in which the laser diode comprises four parts (A, B, C and D).
- Part-A is a gain section with an embedded grating
- Part-B is also a gain section but without a grating
- Part-C is a region without a grating but with a higher band gap energy as compared to Parts A and B
- Part-D is a further gain section with an embedded grating (similar to Part-A).
- Part-B and Part-C are driven by differential RF modulation signals with a DC bias, where the amplitude of the RF signal and the level of DC bias can be adjusted independently.
- the RF signals to Part-B and Part-C can be adjusted independently by means of the two attenuators (ATT).
- the end sections of the device, Part-A and Part-D are simply driven by a DC source, in order to provide gain.
- the lasing wavelength is mainly determined by Part-A and Part-D, which are gain sections with embedded distributed feedback gratings.
- RF modulation of the optical signal is mainly performed by Part-B but, as discussed above, unwanted phase modulation occurs in addition to the desired amplitude modulation.
- phase modulation resulting in Part-B is compensated by Part-C, where phase modulation occurs without amplitude modulation. This is as a result of the lasing wavelength being far from the band edge of Part-C of the device, as its energy band gap is larger than that of the other three parts. As before, this also ensures that optical loss in the phase section is kept low.
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Semiconductor Lasers (AREA)
Abstract
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2003216843A AU2003216843A1 (en) | 2002-03-15 | 2003-03-17 | Directly modulated laser diode with chirp control |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0206204.0 | 2002-03-15 | ||
GB0206204A GB0206204D0 (en) | 2002-03-15 | 2002-03-15 | Direct modulation of laser diode with chirp control |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2003079507A2 true WO2003079507A2 (fr) | 2003-09-25 |
WO2003079507A3 WO2003079507A3 (fr) | 2004-06-10 |
Family
ID=9933083
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2003/001185 WO2003079507A2 (fr) | 2002-03-15 | 2003-03-17 | Diode laser a modulation directe et a commande de fluctuation de longueur d'ondes |
Country Status (3)
Country | Link |
---|---|
AU (1) | AU2003216843A1 (fr) |
GB (1) | GB0206204D0 (fr) |
WO (1) | WO2003079507A2 (fr) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016112087A1 (fr) * | 2015-01-06 | 2016-07-14 | Applied Optoelectronics, Inc. | Laser à semi-conducteur à deux sections ayant une section de réseau insensible à la modulation afin de réduire la compression d'impulsions |
CN112993753A (zh) * | 2021-02-07 | 2021-06-18 | 桂林雷光科技有限公司 | 一种单片集成波导装置及其集成半导体芯片 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4669086A (en) * | 1983-04-11 | 1987-05-26 | Nec Corporation | Frequency-stabilized semiconductor laser oscillator |
US5325225A (en) * | 1989-11-30 | 1994-06-28 | Nec Corporation | Method of optical transmission and optical transmitter used in the same |
EP0635917A1 (fr) * | 1993-07-23 | 1995-01-25 | Mitsubishi Denki Kabushiki Kaisha | Modulateur optique |
US5774485A (en) * | 1995-09-20 | 1998-06-30 | Siemens Aktiengesellschaft | Wavelength-tunable laser device |
WO2001095444A2 (fr) * | 2000-06-02 | 2001-12-13 | Agility Communications, Inc. | Lasers haute puissance manufacturables a reflecteur bragg reparti et a reseau echantillonne |
-
2002
- 2002-03-15 GB GB0206204A patent/GB0206204D0/en not_active Ceased
-
2003
- 2003-03-17 WO PCT/GB2003/001185 patent/WO2003079507A2/fr not_active Application Discontinuation
- 2003-03-17 AU AU2003216843A patent/AU2003216843A1/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4669086A (en) * | 1983-04-11 | 1987-05-26 | Nec Corporation | Frequency-stabilized semiconductor laser oscillator |
US5325225A (en) * | 1989-11-30 | 1994-06-28 | Nec Corporation | Method of optical transmission and optical transmitter used in the same |
EP0635917A1 (fr) * | 1993-07-23 | 1995-01-25 | Mitsubishi Denki Kabushiki Kaisha | Modulateur optique |
US5774485A (en) * | 1995-09-20 | 1998-06-30 | Siemens Aktiengesellschaft | Wavelength-tunable laser device |
WO2001095444A2 (fr) * | 2000-06-02 | 2001-12-13 | Agility Communications, Inc. | Lasers haute puissance manufacturables a reflecteur bragg reparti et a reseau echantillonne |
Non-Patent Citations (4)
Title |
---|
DELORME F ET AL: "BUTT-JOINTED DBR LASER WITH 15 NM TUNABILITY GROWN IN THREE MOVPE STEPS" ELECTRONICS LETTERS, IEE STEVENAGE, GB, vol. 31, no. 15, 20 July 1995 (1995-07-20), pages 1244-1245, XP000525768 ISSN: 0013-5194 * |
J-M LOURTIOZ ET AL: "Fourier-transform-limited pulses from gain-switched distributed Bragg reflector lasers using simultaneous modulation of gain and phase sections" ELECTRONICS LETTERS, vol. 28, no. 16, 30 July 1992 (1992-07-30), pages 1499-1500, XP002274207 * |
MARSH J H: "QUANTUM WELL INTERMIXING" SEMICONDUCTOR SCIENCE AND TECHNOLOGY, INSTITUTE OF PHYSICS. LONDON, GB, vol. 8, no. 6, 1 June 1993 (1993-06-01), pages 1136-1155, XP000400527 ISSN: 0268-1242 * |
MASON B ET AL: "DIRECTLY MODULATED SAMPLED GRATING DBR LASERS FOR LONG-HAUL WDM COMMUNICATION SYSTEMS" IEEE PHOTONICS TECHNOLOGY LETTERS, IEEE INC. NEW YORK, US, vol. 9, no. 3, 1 March 1997 (1997-03-01), pages 377-379, XP000684418 ISSN: 1041-1135 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016112087A1 (fr) * | 2015-01-06 | 2016-07-14 | Applied Optoelectronics, Inc. | Laser à semi-conducteur à deux sections ayant une section de réseau insensible à la modulation afin de réduire la compression d'impulsions |
US9762028B2 (en) | 2015-01-06 | 2017-09-12 | Applied Optoelectronics, Inc. | Two-section semiconductor laser with modulation-independent grating section to reduce chirp |
CN107454990A (zh) * | 2015-01-06 | 2017-12-08 | 祥茂光电科技股份有限公司 | 具有独立调制光栅区段以减少啁啾的双区段半导体激光器 |
CN112993753A (zh) * | 2021-02-07 | 2021-06-18 | 桂林雷光科技有限公司 | 一种单片集成波导装置及其集成半导体芯片 |
Also Published As
Publication number | Publication date |
---|---|
GB0206204D0 (en) | 2002-05-01 |
WO2003079507A3 (fr) | 2004-06-10 |
AU2003216843A1 (en) | 2003-09-29 |
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