WO1988008998A1 - Ameliorations apportees a la modulation d'un faisceau lumineux - Google Patents

Ameliorations apportees a la modulation d'un faisceau lumineux Download PDF

Info

Publication number
WO1988008998A1
WO1988008998A1 PCT/US1988/001451 US8801451W WO8808998A1 WO 1988008998 A1 WO1988008998 A1 WO 1988008998A1 US 8801451 W US8801451 W US 8801451W WO 8808998 A1 WO8808998 A1 WO 8808998A1
Authority
WO
WIPO (PCT)
Prior art keywords
frequency
laser diode
current
drift
magnitude
Prior art date
Application number
PCT/US1988/001451
Other languages
English (en)
Inventor
Paul Bernard Mauer
Badhri Narayan
James Edward Roddy
Original Assignee
Eastman Kodak Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Company filed Critical Eastman Kodak Company
Publication of WO1988008998A1 publication Critical patent/WO1988008998A1/fr

Links

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
    • H01S5/06209—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in single-section lasers
    • H01S5/06213—Amplitude modulation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/213—Fabry-Perot type
    • 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
    • H01S5/06209—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in single-section lasers
    • H01S5/0622—Controlling the frequency of the radiation

Definitions

  • This invention relates to modulation of the intensity of the beam of light, having at least a degree of coherence, derived from a source, such as a laser diode, whose emission frequency varies with the nature of the electrical energy supplied to the source.
  • Proposals for modulating the intensity of light beams derived from laser diodes have included modulation of the light before it exits the diode and modulation of the beam after it exits the diode.
  • the former has been termed internal modulation and the latter has been termed external modulation.
  • internal modulation has involved variation of the electrical current applied to the laser diode.
  • the wavelength of the light emitted by a laser diode is dependent on the current applied to the diode. It is believed that such dependency is due to at least two causes. Firstly, that the refractive index of the optical cavity of the laser diode is dependent on current density and temperature. Secondly, the temperature, and hence length of the optical cavity, varies with current density.
  • the intensity modulation is accompanied by a frequency change and if the intensity modulation is sufficiently large as to be useful then the frequency change will also be large.
  • a dispersive optical system e.g. as a transmitter in a fiber optic communication system
  • a diffractive optical system e.g. as a light source in a writing scanner including, as a diffractive element, a hologon.
  • U.S. Patent Speci ication No. 4,638,483 discloses a modulatable light generator including means for producing a collimated beam of light, including a laser diode. There are drive means for supplying electrical current to the laser diode to cause the laser diode to emit an output beam of light. The frequency of the beam of light is variable by varying the current supplied by the drive means. There is an interferometer disposed in the collimated beam. The interferometer acts as a convertor for converting frequency modulation to intensity modulation. Thus, by varying the frequency of the beam incident on the interferometer so the intensity of the beam output from the interferometer is varied as the interference in the interferometer varies between constructive and destructive.
  • the present invention recognizes that the frequency of the output of a laser diode varies by jumps in which a relatively high rate of change of frequency occurs per unit variation in magnitude of current supplied to the laser diode and by drifts between jumps.
  • the drifts exhibit relatively low rates of change of frequency per unit variation in magnitude of the current.
  • the present invention ensures that the laser diode is operated in only a drift region so that only small frequency changes occur and the large frequency changes associated with jumps are avoided.
  • the current supplied to the laser diode is varied by an amount less than the current variation needed to cause the drift between successive jumps.
  • the frequency may be shifted by drifting between a frequency at which destructive interference occurs in the interferometer and another frequency at which constructive interference occurs, without causing a jump in frequency. If the laser diode emits a divergent beam, the beam is collimated before it is directed onto the interferometer.
  • the current supplied to the laser diode is adjusted so as to cause the laser diode to emit light at a frequency approximately at the middle of a region of drift.
  • the magnitude of the current may be varied by an amount less than that necessary to cause the frequency to vary from the frequency approximately at the middle of the region of drift to a frequency at which a jump in frequency occurs at an end of said region of drift.
  • the present invention also resides in a modulatable light generator for performing the method of the invention.
  • Fig. 1 is a plot of optical output power against forward current for a typical laser diode
  • Fig. 2 is a plot of lasing peak wavelength against forward current for a typical laser diode
  • Fig. 3 is a plot of the normalized intensity of two adjacent passbands of a Fabry-Perot etalon
  • Fig. 4 is similar to Fig. 3 but includes four curves, one for each of four different reflectances of the reflective surfaces of the etalon;
  • Fig. 5 is a schematic representation of a writing holographic scanner including a modulatable light source in accordance with the present invention
  • Fig. 6 is a schematic representation of a cross-section of a Fabry-Perot etalon.
  • Fig. 1 is a plot of the optical output power P against forward current I for a typical laser diode.
  • the curve 20 has a low slope portion 22 and a greater slope portion 24.
  • the curve portion 22 is the spontaneous emission region and the curve portion 24 is the lasing region.
  • the curve demonstrates that the optical output power of a laser diode increases with forward current. It is known to modulate a laser diode by varying the forward current. For example, with a particular laser diode which has a threshold current It..h of
  • Fig. 2 is a plot, for an exemplary laser diode, of the variation in wavelength ⁇ with variation in forward current I.,. Variation in forward current causes a change
  • the jumps 26 are of about 0.3 nm and the frequency change in a drift is at a rate of about 0.0075 nm per milliampere. While the extents of the drift regions vary, there are drift regions 28 which extend for about 20 mA, that is, the current can be changed by about 20 mA after one jump, before the next. Some drift regions in some laser diodes may be substantially bigger.
  • Fig. 6 illustrates a cross-section of an interferometer, in this embodiment a Fabry-Perot etalon 30, which, as is known, comprises a transparent plate 32 having planar, parallel opposed surfaces 34 which have reflective coatings 36.
  • the coatings 36 are partially transparent to allow an incident beam 38 to enter the etalon and to allow a beam 40 to leave the etalon 30.
  • the coatings are also reflective to light incident on them at the interfaces with the plate 32 so that they internally reflect a portion of the light in the plate 32. It is known that the pathlength of the light beam within the plate 32 determines, for a particular wavelength, whether there is constructive or destructive interference and hence determines, in part, the fraction of the energy in the input beam which appears in the output beam.
  • the effective pathlength within the plate 32 is, of course, dependent on the physical thickness of the plate, which is in turn dependent on temperature; on the refractive index of the material of the plate; and on the angle of incidence of the input beam 38. If these three parameters, thickness, refractive index, and incidence angle, are kept constant, and the wavelength of the incident light is varied, then the intensity of the output beam 40 will vary as the frequency of the incident beam 38 is varied. Thus, with the incident beam 38 being the collimated output beam of a laser diode, the intensity of the output beam 40 is dependent on the frequency of the light emitted by the diode.
  • Fig. 3 is a plot of the normalized intensity of the transmitted light against phase difference ⁇ , which is related to wavelength.
  • the peaks in the output beam intensity i.e. the passbands of the etalon, occur at peaks in the phase difference g & iven by: wherein m is an integer.
  • the output beam may have a low intensity with spaced passbands of high intensity.
  • the actual intensity of the output beam relative to the input beam is dependent on the transmittance of the reflective coatings 36.
  • the transmittance and the reflectance are inversely dependent on one another.
  • Fig. 4 shows a plurality of plots, each similar to Fig. 3, but for different values of reflectance R of the coatings. It will be observed that the contrast between "on” and “off” decreases with decreasing reflectance and the width of the "on" passbands increases with decreasing reflectance.
  • the design and construction of etalons to achieve required performance characteristics is believed to be sufficiently well understood by those skilled in the art that further description herein is deemed unnecessary.
  • the parameters important to satisfactory performance of the etalon in the present context are: peak transmission; width of the passband; and the separation of the passbands. Finesse, the ratio of the passband separation to the width of the passband, is used as a measure of the tunability of the etalon.
  • n index of refraction of etalon
  • Fig. 5 is a schematic representation of a holographic writing scanner embodying a modulatable light source in accordance with the present invention.
  • Laser scanners are well known and only those features necessary for an understanding of the present invention will now be described. It is to be understood that other features not described and necessary for the scanner to function may be derived from the art.
  • the scanner includes a transparent disc 50 having thereon a plurality of sector-shaped facets each containing, in known manner, identical diffraction gratings with the lines of the gratings being tangential.
  • the disc 50 is mounted on the shaft 52 of a motor 54 controlled for rotation at constant speed by a controller 55.
  • a laser diode 56 has a divergent output beam 58 which is collimated by a collimator 60 into a collimated beam 62.
  • the collimated beam 62 is directed at the disc 50.
  • the Fabry-Perot etalon 30 Between the collimator 60 and the disc 50 and in the collimated beam 62, there is the Fabry-Perot etalon 30. In the present embodiment the angle of incidence of the beam on the etalon is close to normal. Normal incidence is avoided to minimize reflections back through the system.
  • the incident beam 60 is diffracted and scanned along an approximately linear path.
  • the diffracted beam has the reference numeral 64 in Fig. 5.
  • the diffracted, scanning beam 64 is incident on an f ⁇ lens 66 which serves to focus the beam onto the surface of a drum 68 about which is wrapped a web 70 of photosensitive material.
  • the etalon 30 is provided with a device 80 for keeping the etalon at constant temperature.
  • the device 80 is controlled by a control device 82.
  • a signal source 72 constituting drive means for the laser diode, supplies electrical energy to the light source and controls the nature of that energy. It is the current which the signal source 72 controls.
  • the forward current supplied to the laser diode 56 by the signal source has an instantaneous magnitude related to the signal desired to be applied by the light beam to the photosensitive web, i.e. the current is of one of two values depending on whether the beam is to be "on” or "off” .
  • the laser diode 56, the collimator 60 and the etalon 30 constitute a modulatable light generator in accordance with the present invention.
  • the frequency of the beam output by the laser diode is dependent on temperature. It may be found necessary to stabilize the diode against temperature drifts occurring due, for example, to ambient conditions or due to relatively long term heating of the diode by the applied forward current. Such temperature changes may be regarded as long term and are to be distinguished from the instantaneously occurring temperature changes in the junction of the diode due to variations in the forward current. Such instantaneously occurring changes are acceptable and, indeed, are part of the mechanism for causing small frequency changes, in accordance with the invention.
  • Fig. 5 shows a temperature stabilizing means 74, in the form of a thermoelectric cooler, and its controller 76, for controlling and stabilizing the temperature of the diode 56.
  • the current Ig applied by the signal source 72 is selected not only so that the beam 58 has the desired intensity but also so that the frequency of the beam is approximately at the middle of a drift region 28, i.e. it is approximately equally spaced from the adjacent jumps 26. (see Fig. 2).
  • This middle position is chosen so that a maximum change in frequency, either up or down, can be accommodated without a frequency jump being encountered. Let it be assumed that at that mid point the frequency is such that there is constructive interference in the etalon. If the current is now varied incrementally up or down to I D , the frequency of the output beam 58 will change so that there is now destructive interference in the etalon 30 and the beam 62 will be "off".
  • the beam is turned “on” and “off” by the signal source 72 applying the appropriate forward current I Terra or I_, respectively, to the diode 56.
  • the timing of the signals applied to the diode is related to the angular position of the disc (being driven in rotation by the motor 54) which controls the position of the point of incidence of the beam in its scan line along the photosensitive web 70 on the drum 68.
  • Fig. 2 shows the lengths and slopes of the drift regions 28 as being substantially equal and the heights of the jumps 26 as being substantially equal. This condition might not be found in reality and the lengths of some drift regions will be longer than others. Indeed each laser diode, even of the same batch of the same model, will have its own characteristics in this respect. Thus, it will probably be advantageous to analyze each diode and select that drift region which has the most advantageous combination of length and slope. The selected drift region becomes the drift region in which the diode is operated. Overriding the selection of the drift region is that the frequency of the output beam be acceptable to the system in which the diode is employed.
  • the frequency change needed to cause a change in the beam from "on” to “off” in a modulator in accordance with the invention need be only of the order of a hundredth of the frequency change which occurs when the current in a laser diode is varied sufficiently to cause the beam output by the diode to go from “on” to “off”.
  • the displacement of the "spot" where the beam is incident on the photosensitive web, transversely of the scan line and due to the frequency change in the diffractive system may be so small as to be unnoticeable, whereas in a system lacking the interferometer displacement would be intolerable.
  • a particular etalon does not have the desired pathlength with the near normal angle of incidence described above, or that it is desired for some other reason to vary the pathlength in the etalon.
  • Such variation may be achieved by rotating the etalon about an axis parallel to the planes of the surfaces on which are the reflective coatings. This rotation effectively changes the angle of incidence of the light beam on the etalon. If the angle of incidence is changed, the angle of the beam within the transmissive plate 32 is also changed. Change in the angle of the beam within the plate causes change in the pathlength within the plate.
  • temperature stabilizing means may be provided for the diode.
  • temperature stabilizing means it is used in the selection of the particular frequency drift region 28 in which the diode is operated.
  • the temperature of the diode is adjusted until, at a particular selected forward current, the frequency of the output beam and the frequency at the middle of the drift region selected for the diode to operate in, are the same.
  • both the current and the temperature of the diode may be adjusted to arrive at an operating condition in the middle of a selected drift region 28.
  • a writing scanner as diagrammatically represented in Fig. 5 was designed having the following characteristics and performance parameters:
  • the laser 56 used was a Hitachi HLP-1400 laser diode with a wavelength of 830 nm and an output power of approximately 10 milliwatts.
  • the thermoelectric cooler 74 and controller 76 are stock items available from Midland Ross.
  • the signal source 72 was a Wavetek Model 166 Pulse/Function Generator. Any suitable microscope objective can be used for the collimating lens 60.
  • the etalon 30 is obtained from Laser Optics and is 3 mm thick with 97% reflectance coatings 36 on each surface.
  • the finesse is 103, having a passband width of 334 MHz and a passband separation of 34.5 GHz,
  • Incidence angle diffraction angle _. 45°
  • the hologon disc 50 is attached to a motor
  • the collimated scanning beam 64 from the hologon is focused to the film plane by the F ⁇ lens 66.
  • the lens not only focuses the beam but also provides a flat field focal plane and compensates for distortion, such that the spot motion is directly proportional to the hologon rotation angle.
  • the hologon scanner provides the high speed horizontal scan.
  • the slower speed vertical scan is accomplished by rotating the drum 68.
  • the photosensitive material 70 is photographic film, Kodak S0-156.
  • the surface speed needed at the drum is 0.073 inches/second.
  • the information from the signal source 72 must be synchronized to the start-of-line and start-of-page signals provided by the appropriate detectors. These functions are not shown in Figure 5 but are well known in the art.
  • the operating point of the etalon 30 initially can be set on the side of a passband by mechanically tilting the etalon and then fine tuning by adjusting the laser bias current.
  • a servo control mechanism can be added to track the drift.
  • One technique is to control the etalon temperature with a thermoelectric cooler. The device 80 and control device 82 might be used for this purpose (see Fig. 5).
  • An alternative approach is to pick off a portion of the beam after the etalon with a beamsplitter and detect it with a photodiode. An error signal derived from the photodiode signal is used to modify the laser bias to keep the laser operating on the middle of the slope of the etalon passband.
  • collimating means are provided to collimate the divergent beam emitted by the laser diode, it is to be understood that if the laser diode emits a collimated beam, collimating means need not be provided. At present, it is believed that there does not exist a laser diode which emits a collimated beam, but that progress is being made towards such a laser diode. Thus, such a diode would constitute means for producing a collimated light beam whereas at present such means might comprise a laser diode emitting a divergent beam and collimating means for collimating the divergent beam into a collimated beam.
  • the interferometer is- a Fabry-Perot etalon.
  • the etalon may include two transmissive plates maintained in parallel spaced relationship by low thermal expansion material. The plates have reflective transmissive coatings on their facing surfaces.
  • other forms of interferometers for example, a Twyman-Green interferometer, may be used in other embodiments of the invention.
  • the frequency changes needed to cause the interferometer to create an intensity modulation from the frequency modulated light applied to it may be kept very small.

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • Semiconductor Lasers (AREA)

Abstract

Le procédé et l'appareil décrits servent à moduler le faisceau de sortie aligné par collimation (62) d'une diode à laser (56) dont la fréquence d'émission varie avec l'amplitude du courant alimentant la diode. Les changements de fréquence ont lieu par sauts (26), pour lesquels la vitesse de changement de fréquence est relativement élevée, et par écarts (28) entre les sauts (26). Pour les écarts (28) les vitesses de changement de fréquence par unité de variation de l'amplitude du courant sont relativement faibles. Le faisceau (38, 58) est dirigé sur un interféromètre (30) destiné à convertir la modulation de fréquence en une modulation d'amplitude. Le courant alimentant la diode (56) varie selon une quantité inférieure au courant nécessaire pour produire l'écart (28) entre les sauts succéssifs. Ainsi, la fréquence peut être déplacée par déviation entre une fréquence à laquelle une interférence destructive se produit dans l'interféromètre (30) et une autre fréquence à laquelle se produit une interférence constructive, sans provoquer un saut de fréquence.
PCT/US1988/001451 1987-05-04 1988-05-03 Ameliorations apportees a la modulation d'un faisceau lumineux WO1988008998A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US4549887A 1987-05-04 1987-05-04
US045,498 1987-05-04

Publications (1)

Publication Number Publication Date
WO1988008998A1 true WO1988008998A1 (fr) 1988-11-17

Family

ID=21938231

Family Applications (2)

Application Number Title Priority Date Filing Date
PCT/US1988/001451 WO1988008998A1 (fr) 1987-05-04 1988-05-03 Ameliorations apportees a la modulation d'un faisceau lumineux
PCT/US1988/001450 WO1988008997A1 (fr) 1987-05-04 1988-05-03 Ameliorations apportees a la modulation d'un faisceau lumineux

Family Applications After (1)

Application Number Title Priority Date Filing Date
PCT/US1988/001450 WO1988008997A1 (fr) 1987-05-04 1988-05-03 Ameliorations apportees a la modulation d'un faisceau lumineux

Country Status (1)

Country Link
WO (2) WO1988008998A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2512298A1 (fr) * 1981-09-03 1983-03-04 Int Standard Electric Corp Systeme et methode de modulation de frequence optique
GB2161925A (en) * 1984-07-20 1986-01-22 Stc Plc Fibre optic sensor
WO1986001006A1 (fr) * 1984-07-30 1986-02-13 American Telephone & Telegraph Company Source de lumiere modulee en intensite a haute vitesse

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2512298A1 (fr) * 1981-09-03 1983-03-04 Int Standard Electric Corp Systeme et methode de modulation de frequence optique
GB2161925A (en) * 1984-07-20 1986-01-22 Stc Plc Fibre optic sensor
WO1986001006A1 (fr) * 1984-07-30 1986-02-13 American Telephone & Telegraph Company Source de lumiere modulee en intensite a haute vitesse

Also Published As

Publication number Publication date
WO1988008997A1 (fr) 1988-11-17

Similar Documents

Publication Publication Date Title
US5691989A (en) Wavelength stabilized laser sources using feedback from volume holograms
US6829258B1 (en) Rapidly tunable external cavity laser
US6816516B2 (en) Error signal generation system
EP0550929B1 (fr) Dispositif optique et appareil d'exploration d'une surface d'information muni d'un tel dispositif optique
US5862162A (en) External resonator type wavelength- tunable light source
US4250465A (en) Radiation beam deflection system
JP3212153B2 (ja) 可変波長光源を用いた光学出力装置でのスポット位置制御用の装置
CA2132473C (fr) Systeme et methode pour commander la puissance du spot dans un dispositif de balayage de trame
US6324193B1 (en) Continuously wavelength-tunable monomode laser source
CN1287495C (zh) 具有衍射光学元件的波长可调激光器
JP5121150B2 (ja) 波長可変レーザ光源
JPH0611750A (ja) 光学装置及び光学式走査装置
JP3212152B2 (ja) 可変波長光源を用いた光学出力装置でのスポット位置制御方法
JP4916427B2 (ja) レーザビーム走査装置
JPH0818167A (ja) 可変波長光源装置
WO1988008998A1 (fr) Ameliorations apportees a la modulation d'un faisceau lumineux
JPS6179286A (ja) レーザダイオード及びそのモードホツピング防止方法
US6785305B1 (en) Tuneable, adjustment-stable semiconductor laser light source and a method for the optically stable, largely continuous tuning of semiconductor lasers
JPH0745890A (ja) 外部共振器型半導体レーザ
JP2002204025A (ja) レーザー光源および画像形成装置
US4971412A (en) Laser optical system having a phase correction for controlling intensity distribution
KR102138790B1 (ko) 적층 세라믹 커패시터를 이용한 광원 및 광학필터
US20240094595A1 (en) Dynamic correction for an acousto-optic deflector
KR100286066B1 (ko) 광학장치와 광학적 주사장치 및 광학적 정보기록장치
CN118263758A (en) Tunable laser

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): DE JP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642