Abstract: In a method, a gain medium is provided having an absorption coefficient that varies with wavelength. An absorption coefficient curve of the absorption coefficient or a range of wavelengths comprises peaks and valleys. A pump module is operated to output pump energy at an operating wavelength within one of the valleys, at which the absorption coefficient is approximately less than 40% of the absorption coefficient at an adjacent peak of the absorption to coefficient curve defining the valley. The pump energy is directed through the gain medium. A portion of the pump energy is absorbed with the gain medium and laser light is emitted from the gain medium responsive to the absorbed pump energy. The non-absorbed pump energy (feedback pump energy) is fed back to the pump module. The operating wavelength of the pump energy is stabilized using the feedback pump energy.

Abstract: A laser system such as a DPSS green laser uses a laser diode pump source that is specially selected so that the wavelength of diode source is centered around the optimal source wavelength, typically 808 nm, which produces the optimal green laser output from the system. Unlike prior systems in which the source wavelength is at 808 nm at typical ambient temperature of about 25° C., in the system disclosed, the source wavelength is at 808 nm at a temperature significantly higher than ambient, which may be as high as about 40° C. In this system optimum performance can be established and maintained in a broad temperature range such as 0˜50° C. using only a heating element adjacent to the diode laser pump source. No cooling is required. Cost, size, and power requirements of the system are therefore minimized.

Abstract: A drive signal for driving a semiconductor laser is generated on the basis of an image signal inputted in synchronism with a pixel clock. A bias signal to the semiconductor laser is generated at a timing earlier than the drive signal by a predetermined time. The bias signal is disabled in synchronism with the leading edge of the drive signal.

Abstract: A method of controlling a pulse output in a master oscillator-power amplifier type fiber pulse laser apparatus including a master oscillator unit and a power amplifier unit connected to the master oscillator unit is provided. The method includes starting the master oscillator unit before starting the power amplifier unit.

Abstract: A first light feedback element is arranged at an optical distance L1 from a front facet of a semiconductor laser from which an output light is emitted on an optical path of the output light. An i-th light feedback element is arranged at an optical distance Li from the front facet on the optical path of the output light, where i=2 to n, n is a positive integer not less than 2, and Li>L1. L1 and Li satisfies ((M?1)+0.01)<(Li/L1)<(M?0.01), where M is a positive integer not less than 2, satisfying (M?1)<(Li/L1)?M.

Abstract: Systems and methods for stripping an optical mode from a semiconductor laser. A waveguide layer is included in the semiconductor laser and is typically arranged beneath the active region. The waveguide layer is configured to match the phase of the second order mode. The waveguide layer does not substantially match the primary optical mode of the laser. By matching the phase of the second order mode, the confinement of the second order mode is reduced and the second order mode strongly couples with the waveguide layer. The optical confinement of the primary mode is not substantially reduced. The side-mode suppression ratio is thereby improved by stripping the second order mode from the active region.

Abstract: A gas discharge laser system bandwidth control mechanism and method of operation for controlling bandwidth in a laser output light pulse generated in the gas discharge laser system is disclosed which may comprise a bandwidth controller which may comprise an active bandwidth adjustment mechanism; a controller actively controlling the active bandwidth adjustment mechanism utilizing an algorithm implementing bandwidth thermal transient correction based upon a model of the impact of laser system operation on the wavefront of the laser light pulse being generated and line narrowed in the laser system as it is incident on the bandwidth adjustment mechanism. The controller algorithm may comprises a function of the power deposition history in at least a portion of an optical train of the gas discharge laser system, e.g., a linear function, e.g., a combination of a plurality of decay functions each comprising a respective decay time constant and a respective coefficient.

Abstract: So as to establish laser light with a desired characteristic downstream a laser light source (151), the light is amplified by an amplifier (107) which is gain modulated (E107G).

Abstract: A powerful high-brightness laser pump modules is configured with a plurality of spaced laser diodes each generating a light beam at a pump wavelength, and respective groups of optical components guiding the light beams along parallel light paths. The groups of the optical components each include a lens assembly and a bending mirror configured to couple the beam light into an output fiber which is common to all groups of the optical component. At least one optical component of each group is provided with a dielectric layer capable of preventing propagation of a backreflected light toward laser diodes at a wavelength different from the pump wavelength.

Abstract: A system for real-time linewidth reduction in an optical source includes a laser device comprising a back facet, wherein the laser device receives a modulated input current and generates an optical output signal; an etalon device disposed adjacent to the back facet of the laser device, wherein the etalon device receives an optical feedback output signal from the back facet of the laser device, and wherein the etalon device monitors the optical feedback output signal for changes in frequency and, if they exist, generates an optical correction output signal; a photo-detector device disposed adjacent to the etalon device, wherein the photo-detector device receives the optical feedback and correction output signals, and wherein the photo-detector device converts the optical feedback and correction output signals into an electrical signal; and a feedback correction loop coupled to the photo-detector device, wherein the feedback correction loop receives the electrical signal from the photo-detector device and gener

Abstract: A laser frequency stabilizing apparatus stabilizes an oscillation frequency of laser light by varying a resonator length on the basis of a saturated absorption line included in an optical output signal. The optical output signal is obtained by irradiating an absorption cell with the laser light. The laser frequency stabilizing apparatus includes: a light detecting section for detecting the optical output signal; a differential signal detecting section for detecting a differential signal of the optical light signal; an actuator for varying the resonator length; a drive section for driving the actuator; and a control section for controlling the drive section on the basis of the differential signal.

Abstract: Techniques and devices to stabilize a passively mode-locked laser against the timing jitter by using a feedback control signal based on a signal component at a high harmonic frequency of the laser pulse repetition frequency in the laser output to control the optical path length of the laser resonator.

Abstract: Anisotropic crystals such as Nd:YVO4, Nd:YLF, and Nd:GdVO4 have become preferred gain materials for many laser applications. The anisotropic gain medium without ancillary compensation ensures there is no degradation of laser modes when passing through the gain medium. An optical power amplifier that incorporates an anisotropic gain medium achieves power scaling with multiple passes while also maintaining good mode matching between the laser and the pump during each pass. Preferred embodiments implement for multiple passes of a seed laser beam through an anisotropic gain medium with substantially zero angular beam displacement during each pass. The multi-pass system provides an economical, reliable method of achieving high TEM00 power to meet the demands of micromachining, via drilling, and harmonic conversion applications.

Abstract: A method of stabilising a laser in order to maintain the laser in SLM operation is disclosed. The resonator cavity of the laser is modulated by a modulation signal applied to a piezo-electric transducer 10 coupled to the output coupler 2 of the laser. The modulation signal is also multiplied by a signal indicative of the energy of the laser radiation within the resonator cavity. The product of these two signals is then low-pass filtered to provide an error signal which is additionally applied to the piezo-electric transducer 10 so as to further vary the optical length of the resonator cavity.

Abstract: A laser system 1 comprises six solid state diode laser modules 37.1 to 37.6 whose output beams are directly coupled into beam steering devices 38.1 to 38.6 and thereby routed to laser combining dichroic mirrors 39.1 to 39.6, which combine the individual laser beams into a single, co-aligned beam. The combined laser beam is directed into an optical fiber 41.1 for delivery to a target optical instrument such as a microscope. The output beam from delivery optical fiber 41.1 is coupled to the target instrument via fiber output collimating optics 42.1. The output of each of the diode lasers 37.1 to 37.6 is controlled by direct modulation of the lasers' control (drive) currents.

Abstract: A light emitting device is disclosed that emits light from the surface in a broad spectral range and in a broad range of angles tilted with respect to the direction normal to the exit surface. An apparatus for generating wavelength-stabilized light is formed of a light-emitting device, an external cavity and at least one external mirror. Light emitted by the light-emitting device at a certain preselected angle, propagates through the external cavity, impinges on the external mirror and is reflected back. Light emitted at other angles does not impinge on the external mirror. Thus, a feedback occurs only for the light emitted at a preselected angle. Light impinged on the external mirror and reflected back undergoes interference with the emitted light. The interference can be constructive or destructive. Constructive interference results in a positive feedback. The positive feedback occurs, if light emitted by the light-emitting device is reflected back and reaches the active region in phase, i.e.

Abstract: The invention discloses an optical transmission module with digital adjustment and method thereof. The module includes a laser (21), a laser driver (22), an automatic power adjustment circuit (23), an automatic temperature adjustment circuit (24), a digital adjustment circuit (25) and a memory (26). The digital adjustment circuit, consisted of a digital-to-analog converter or a digital adjustment potentiometer, receives a digital adjustment signal and outputs, respectively, a extinction ratio adjustment signal and a cross point adjustment signal to the laser driver, an optical power adjustment signal to the automatic power adjustment circuit and an optical wavelength adjustment signal to the automatic temperature adjustment circuit. The memory stores data, using for on-line adjustment of the optical transmission module, at least including parameters of said optical transmission module and said laser emitting optical power parameters, to be reported upward.

Abstract: In a laser power control apparatus for controlling a laser power of a combination drive, first laser light Lc applied onto a first optical disk and second laser light Ld applied onto a second optical disk is collected by one photodetector 8.

Abstract: A cut-out portion of a ground conductor is located in a region where a header faces a flexible board from the junction of a signal pin and a signal line and faces the signal line. The size of the cut-out portion is determined so that the impedance of the signal pin is matched to the impedance of the signal line.

Abstract: An optical power control apparatus includes a changing unit which changes, a plurality of number of times, the value of a current flowing to an optical beam output apparatus, and an obtaining unit which obtains, in correspondence with each current value, a peripheral optical power representing an optical power at the peripheral part of the spot of the optical beam output from the optical beam output apparatus. The optical power control apparatus also includes a correction unit which corrects the peripheral optical power so that the peripheral optical power and a central optical power representing an optical power at the central part of the spot have an approximately linear relationship in correspondence with each current value. The optical power control apparatus also includes a control unit which controls the optical power of the optical beam output from the optical beam output apparatus in accordance with the corrected peripheral optical power.

Abstract: According to one embodiment, an optical disk drive includes a monitor diode which monitors a laser output of a laser diode irradiating a laser beam to an optical disk, a detector which sets an output termination mode when a state that a monitor signal obtained from the monitor diode exceeds a first reference value continues over a predetermined period is detected from a deglitch, a switch section which terminates the laser output of the laser diode upon setting of the output termination mode, and a controller which supplying a drive signal for reducing a difference obtained as a comparison result between the monitor signal and a second reference value smaller than the first reference value. The controller serves as a software-based digital filter which realizes an equalizer function of making phase compensation of the comparison result.

Abstract: A semiconductor optical amplifier, an acousto-optic tunable filter, a phase shifter, a lens, and an internal etalon are arranged in a resonator. Outside the resonator, two lenses, two beam splitters, two photo-detectors, and an external etalon are arranged. The internal etalon is a quartz etalon and the external etalon is a crystal etalon. Therefore, the rate of change in transmission peak wavelength of the internal etalon to a temperature change is greater than that of the external etalon.

Abstract: A system of controlling a wavelength of a laser beam is provided. The system comprises a stage for supporting a wafer, an optical convergence unit for emitting the laser beam moving in an optical path toward the stage, and a specific wavelength detecting sensor. The specific wavelength detecting sensor is disposed between the optical convergence unit and the stage. It includes a laser beam absorbing structural body for absorbing a specific wavelength of the laser beam emitting toward the stage. A wavelength controlling unit for selectively controlling the wavelength of the laser beam is also provided.

Abstract: Electroabsorption-modulated Fabry-Perot lasers and methods of making the same are described. In one aspect, a light source includes a Fabry-Perot (FP) laser that is operable to generate multimode laser light, an electroabsorption modulator (EAM) that is configured to selectively absorb and transmit laser light traveling therethrough, and an optical isolator. The optical isolator is on an optical path between the FP laser and the EAM. The optical isolator is configured to transmit laser light traveling along the optical path from the FP laser to the EAM.

Abstract: A laser apparatus for providing a stabilized multi mode laser beam includes an external cavity for providing an optical path for generating a laser beam which is stimulated by a gain medium, where the external cavity has first spectral characteristics, and a mode-selecting filter positioned within the optical path and having second spectral characteristics. The first characteristics and the second characteristics are adjusted to each other, so that the laser beam has at least two selected modes.

Abstract: Compactness is preserved while enabling beam monitoring of optical properties of an output beam by employing a combination of reflection and diffraction. An input beam is reflected, divided using reflection/diffraction, and re-reflected. As a consequence, both a light source and one or more beam monitoring detectors may be disposed along a single side of an optical module. In one embodiment, an input beam is introduced from a first side of an optical module, is reflected by a 45 degree mirror, and is divided by a diffraction grating which redirects a minor portion of the beam energy back to the 45 degree mirror. Following the second reflection from the mirror, the returned portion of the beam is used to measure one or more optical properties.

Abstract: Systems, devices and methods of generating both a precision electrical timing signal as well as a precision optical timing signal. A novel, modified opto-electronic loop oscillator is used to drive a harmonic mode-locked laser. A novel opto-electronic loop has a larger “Q” factor by increasing the electrical loop oscillating frequency ?0 by using a beat note created by the selection of two optical longitudinal modes from the mode-locked laser. The beat note is detected and divided down to drive a modulator that mode-locks the laser. The frequency division stage also reduces the noise.

Abstract: A method and apparatus to automatically control an output power of a laser diode, include generating an error voltage between an output voltage of the laser diode sampled during an automatic power control period and a reference voltage, and performing proportional-integral processing on the error voltage to generate a compensated control voltage and applying the compensated control voltage to the laser diode.

Abstract: A system for stabilizing an output optical power from a laser source against drifts induced by temperature and/or aging, said output optical power including a target optical-modulation amplitude around a target average value includes: a power sensor for sensing the output optical power from the laser source and generating a power sensing signal indicative thereof, and a controller sensitive to the power sensing signal and configured for selectively adjusting the bias (IB) and modulation (IM) currents of the laser source by: detecting an error between the actual average output optical power from the laser source and the target average value,comparing the error against a given error threshold, and when the error reaches the threshold adjusting the bias (IB) and modulation (IM) currents to bring the output optical power from the laser source (1) back to the target average value (Ptarget) and the target optical modulation amplitude (OMAtarget) around the target average value (Ptarget).

Abstract: A control method for a laser diode is conducted such that optical output and OMA (optical modulation amplitude) or extinction ratio of the laser diode are controlled while modulating the optical output of the laser diode by applying a bias current and a modulation current to the laser diode. The method has: a first step of measuring the optical output of the laser diode; a second step of measuring a slope efficiency or a corresponding value of the slope efficiency while conducting APC (automatic power control) to adjust the bias current such that the optical output coincides with a predetermined value; and a third step of adjusting the modulation current by AAC (automatic amplitude control) according to the slope efficiency or the corresponding value of the slope efficiency such that the OMA or extinction ratio coincides with a predetermined value.

Abstract: An image forming apparatus illuminates a pixel formation member with optical energy according to image data specifying a value for each pixel in the image. Some of the optical energy emitted to form a pixel is distributed over surrounding pixels; similarly, a pixel may receive peripheral optical energy that was emitted to form surrounding pixels. The amount of peripheral optical energy thus received is calculated, and the amount of optical energy emitted to form the pixel is adjusted to compensate for the peripheral optical energy, so that the total optical energy received by the pixel has the intended value. Image irregularities are thereby avoided, even if the image formation apparatus employs multiple light-emitting elements with different energy emission distributions.

Abstract: An optical module, such as a package for a vertical cavity surface emitting laser diode (VCSEL) or other light emitting device, includes monitoring of the emitted optical power by tapping the transmitted beam. The module includes a substrate, which carries the light emitting device and an optical monitor. In addition, the module includes a transparent plate with at least two reflective regions that together redirect part of the light from the light emitting device to the optical monitor.

Abstract: A femtosecond laser with stabilized output, and a method for stabilizing the output of a femtosecond laser. The femtosecond laser comprises a regenerative amplifier, a photodetector, a control portion and a variable attenuator, wherein the variable attenuator is provided so as to be capable of controlling an output beam of the regenerative amplifier, the photodetector is provided between the regenerative amplifier and the variable attenuator, the photodetector detects an output beam of the regenerative amplifier and transmits the results of the detection to a power controller, and the power controller controls the variable attenuator depending on the a difference between a predetermined target value and the results.

Abstract: A wavelength locker for use at more than one wavelength includes filters with different characteristics for a corresponding detector. The filters may be etalons having different free spectral ranges, e.g., having different apparent or real thicknesses. If more than three such filters are used outputting offset periodic signals, a reference detector may be eliminated and continuous operation over a wavelength range may be realized.

Abstract: The present invention provides wavelength monitoring and/or control enabling size reduction and low power operation without requiring a complicated optical system in its wavelength monitoring and controlling mechanism. The measurement portion (1) measures temperature by a thermistor (5) in the measurement portion, and measures a bias current by using an LD drive current detecting circuit (6). The LD temperature, optical output and bias current are measured by the measurement portion. The relationship between the LD temperature and wavelengths or between the temperature, bias current and wavelengths is stored in a memory map of the storage portion (2). The central controlling portion (3) calculates wavelengths on the basis of the temperature and the bias current or the temperature information of the measurement portion, and the relationship between the LD temperature, bias current and wavelengths or between the temperature and wavelengths of the storage portion.

Abstract: An optical scanning apparatus includes a light source configured to emit a plurality of laser beams from a plurality of light emitting parts, a beam shaping unit configured to shape the laser beams emitted from the light source, a detection unit provided outside the light source and configured to detect an amount of a laser beam that is not shaped by the beam shaping unit in the laser beams emitted from the light source in an area outside the beam shaping unit, and a light amount control unit configured to control amounts of the laser beams emitted from the light source based on a detection result detected by the detection unit. The detection unit includes a plurality of light-sensitive elements. The light amount control unit controls the light amounts of the laser beams emitted from the light source based on detection results of the light-sensitive elements.

Abstract: The present invention provides a method and apparatus, such as an integrated circuit, to control the optical midpoint power level and the extinction ratio of a semiconductor laser and maintain the optical midpoint power level and the extinction ratio substantially constant at corresponding predetermined levels. Apparatus embodiments include a semiconductor laser, a modulator, a photodetector, an optical midpoint controller, and an extinction ratio controller. The semiconductor laser is capable of transmitting an optical signal in response to a modulation current. The modulator is capable of providing the modulation current to the semiconductor laser, with the modulation current corresponding to an input data signal. The photodetector, which is optically coupled to the semiconductor laser, is capable of converting the optical signal into a photodetector current.

Abstract: In an exposure device comprising a laser controller that is configured as a circuit board capable of independently being changed, and that controls the emission of laser light from a laser emitter emitting laser light on receipt of an instruction for control given from a main controller responsible for overall control of the operation of the exposure device, error control information that is obtained in advance with regard to the circuit board and controls variations of a controlling factor due to a circuit error of the circuit board is stored into a memory provided to the laser controller prior to the provision of the circuit board to the exposure device. On receipt of an instruction for control given from the main controller to cause the emission of laser light in a predetermined amount of light, the laser controller determines a condition of emission of laser light based on the error control information stored in the memory to cause the laser emitter to emit laser light under the condition of emission.

Abstract: A method and apparatus may comprise a seed laser, along with an amplifier laser amplifying the output of the seed laser. A bandwidth metrology module may provide a bandwidth measurement and a bandwidth error signal may be provided using a bandwidth set point. A differential timing system responsive to the error signal can selectively adjust a differential firing time between the seed laser and amplifier laser. A beam dimension and center wavelength control system may adjust a beam dimension, within the cavity of the seed laser, to select bandwidth, and may adjust center wavelength at the same time, using a plurality of beam expansion prisms and at least one other prism or other optical element in the cavity to select center wavelength.

Abstract: This invention describes a technique and apparatus to use any tuneable laser to generate a specified output frequency without controlling its temperature. This technique only involves a thermal sensor and a controller a determine the current(s) of voltage(s) applied to the grating or tuning section(s) to obtain the required wavelength. The control loop can be implemented using a programmed microprocessor, an amplifier and a low pass filter.

Abstract: A semiconductor laser device includes: a first cladding layer, which is made of a nitride semiconductor of a first conductivity type and is formed over a substrate; an active layer, which is made of another nitride semiconductor and is formed over the first cladding layer; and a second cladding layer, which is made of still another nitride semiconductor of a second conductivity type and is formed over the active layer. A spontaneous-emission-absorbing layer, which is made of yet another nitride semiconductor of the first conductivity type and has such an energy gap as absorbing spontaneous emission that has been radiated from the active layer, is formed between the substrate and the first cladding layer.

Abstract: The present invention relates to the analog external cavity lasers (ECLs) including designs, materials, methods of manufacturing and methods of use for such ECLs and packages for such ECLs. Numerous criteria are presented that lead to improved cost/performance for ECLs and for systems incorporating such ECLs.

Abstract: The present invention provides an LD driver able to stably control the output power and the extinction ratio of the optical signal without regarding the coupling mode, the AC mode or the DC mode, between the laser diode and the LD driver. The LD driver includes the peak hold and the bottom hold, each detecting the peak level or the bottom level of the monitored signal, respectively. The bias driver adjusts the bias current so as to equalize the peak level of the monitored signal to the reference, REF_PEAK, while, the modulation driver adjusts the modulation current so as to equalize the bottom level of the monitored signal to the reference, REF_BOTTOM. In the present invention, the adjustment of the modulation current by the modulation driver starts with a substantial delay with respect to the stabilization of the bias current by the bias driver.

Abstract: A description is given of an optical structure (100), in particular for determining and stabilizing the relative phase of short pulses, which contains a broadening device (6) for broadening the frequency spectrum of pulses of electromagnetic radiation, and a frequency multiplier device (8) for multiplying at least one frequency component of the pulses, wherein a focusing lens optic (7) is arranged between the broadening device and the frequency multiplier device, which focusing lens optic can be used to focus the pulses into the frequency multiplier device (8). Uses of this optical structure are also described.

Abstract: PROBLEM TO BE SOLVED: to realize a wide bandwidth light source capable of a stable operation providing a less spectrum variation. SOLUTION: Optical pulses 202 outputted by this optical pulse-generating device 201 are split by optical coupler 210. The one of split optical pulses is inputted in white light-emitting device 204 to emit the white light having the wide bandwidth. The other split is inputted in optical band pass filter 212 in operation-stabilizing circuit 207. Optical detector 213 detects a signal level of a specific wavelength and input in feedback circuit 215 to generate first and second feedback signals 205 and 206. Ring resonator fiber laser 208 uses any one of them and controls a rotation angle of the waveplate to realize stabilization of the output.

Abstract: This disclosure concerns systems, methods and devices for temperature-based control of laser performance. One example of a method is performed in connection with a laser of an optoelectronic transceiver. In particular, the laser is operated over a range of temperatures and the optical output of the laser is monitored. During operation of the laser, the bias current and current swing supplied to the laser are adjusted to the extent necessary to maintain a substantially constant optical output from the laser over the range of temperatures.

Abstract: The present invention is to provide an LD-driver that enables to adjust the waveform of the driving current to the LD even the driver is constituted with a current controlled device such as bipolar transistor. The LD-driver of the invention provides a plurality of modulation current sources each having a function to set the amplitude, the phase and the pulse width of the current output independently. The LD is provided with the modulation current superposed with each current derived from respective current sources.

Abstract: The wavelength of light emitted by a laser and modulated by a frequency response modulator is determined from the power of the emitted light and the current drawn by the modulator. From the temperature and current applied to the modulator and the optical power of the emitted light; the wavelength of the beam of light is determined as a function of a ratio of the current and power for each temperature of operation. As the wavelength of the emitted light shifts, for example as the laser ages or the laser temperature shifts, the inventive methods and devices then detect the wavelength shift and implement any necessary adjustments in the operating conditions of the laser diode. For example, a thermoelectric cooler can be used to heat or cool the laser diode as necessary to thereby adjust the wavelength of the emitted light.

Abstract: Optoelectronic devices and methods are used to maintain a CWDM transmitter operating within design parameters over an extended ambient temperature range. In order to avoid excessive wavelength drift with temperature shifts, lasers in the CWDM transmitters are heated or cooled to a selected temperature, for example by using a thermoelectric cooler. By heating and cooling the lasers, any wavelength drift that an ambient temperature variation might inflict on the laser is minimized to the range hotter or colder than the selected temperature. As the temperature range of the laser increases above the selected temperature, the AC swing driving the laser is increased to maintain a sufficient extinction ratio for acceptable transmitter performance.

Abstract: In a laser module comprising a hermetically sealed container having inside a semiconductor laser device whose emission wavelength is 350˜450 nm, generation of organic volatile gas is suppressed in the container and life of the module is prolonged. In a laser module comprising a hermetically sealed container having inside a semiconductor laser device whose emission wavelength is 350˜450 nm, optical components whose organic volatile gas generation measured by GC/MS is 10 ?g/g or less at 150° C. are positioned in the container. In addition, as an organic adhesive to fix the optical components such as a collimating lens is used an organic adhesive whose organic volatile gas generation measured by GC/MS is 100 ?g/g or less at 150° C.