JP4714716B2 - Control method of light source device - Google Patents

Description

  The present invention relates to a method for controlling a light source device. More specifically, the present invention relates to a method for controlling a light source device that includes a semiconductor laser light source and a second harmonic generation device and can obtain a stable harmonic light output.

  In order to realize a high density optical disc and a high-definition display, a small short wavelength light source is required. As a small short wavelength light source, a semiconductor laser and a quasi phase matching (hereinafter referred to as “QPM”) optical waveguide type second harmonic generation (hereinafter referred to as “SHG”) device (optical waveguide type QPM-SHG device) The coherent light source used has attracted attention (see, for example, Non-Patent Document 1).

  FIG. 21 shows a schematic configuration of an SHG blue light source using an optical waveguide type QPM-SHG device. As shown in FIG. 21, a tunable DBR semiconductor laser 54 having a distributed Bragg reflector (hereinafter referred to as “DBR”) region is used as the semiconductor laser. The wavelength tunable DBR semiconductor laser 54 is a 100 mW class AlGaAs wavelength tunable DBR semiconductor laser in the 0.85 μm band, and includes an active layer region 56, a phase adjustment region 57, and a DBR region 58. The oscillation wavelength can be continuously changed by controlling the injection current into the phase adjustment region 57 and the DBR region 58 at a certain ratio.

The optical waveguide type QPM-SHG device 55, which is a second harmonic generation device, includes an optical waveguide 60 and a periodic domain-inverted region 61 formed on an X plate MgO-doped LiNbO ₃ substrate 59. The optical waveguide 60 is formed by proton exchange in pyrophosphoric acid. The periodic domain-inverted region 61 is produced by forming a comb-shaped electrode on the X-plate MgO-doped LiNbO ₃ substrate 59 and applying an electric field.

In the SHG blue light source shown in FIG. 21, 75 mW laser light is coupled to the optical waveguide 60 for 100 mW laser output. Then, by controlling the amount of current injected into the phase adjustment region 57 and the DBR region 58 of the wavelength tunable DBR semiconductor laser 54, the oscillation wavelength is fixed within the phase matching wavelength allowable width of the optical waveguide type QPM-SHG device 55. . By using this SHG blue light source, about 25 mW of blue light having a wavelength of 425 nm is obtained, but the obtained blue light has a light condensing characteristic with a diffraction limit when the transverse mode is TE ₀₀ mode, and also has a noise characteristic. The relative noise intensity is as small as −140 dB / Hz or less, and it has characteristics suitable for reproducing an optical disc.
Yamamoto et al., Optics Letters Vol.16, No.15, 1156 (1991)

  The optical waveguide type QPM-SHG device, which is the second harmonic generation device, evaluates the blue light output characteristics with respect to the wavelength of the fundamental wave light, and the wavelength width (wavelength tolerance for phase matching) at which the blue light output is halved is 0. It can be seen that it is as small as about 1 nm. This is a serious problem in order to stably obtain the blue light output. In order to solve this problem, a wavelength tunable DBR semiconductor laser is conventionally used as the fundamental light, and the wavelength (oscillation wavelength) of the fundamental light is fixed within the phase matching wavelength allowable range of the optical waveguide type QPM-SHG device. Realizes stable blue light output.

  In general, the oscillation wavelength of the semiconductor laser light source varies with the ambient temperature, and the optimum wavelength of the optical waveguide type QPM-SHG device also varies with the ambient temperature. For this reason, conventionally, the output of blue light has been stabilized by keeping the temperature of the semiconductor laser light source and the optical waveguide type QPM-SHG device constant using a Peltier element or the like.

  However, when considering installation in an optical information processing device such as an optical disk or a laser printer, the average output power changes every moment in the operating state. At this time, even if the amount of heat generated by the semiconductor laser light source changes and the ambient temperature is kept constant using a Peltier element, the temperature of the semiconductor laser light source itself changes, and the oscillation wavelength changes accordingly. Therefore, there is a problem that a stable blue light output cannot be obtained.

  In addition, when a temperature control device such as a Peltier element is not used to reduce the size of the device, the ambient temperature fluctuates more and causes the output fluctuation of the optical waveguide type QPM-SHG device.

  The present invention has been made to solve the above-described problems in the prior art, and includes a method for controlling a light source device that includes a semiconductor laser light source and a second harmonic generation device and can obtain a stable harmonic light output. The purpose is to provide.

To achieve the above object, a control method of a light source device according to the present invention includes a semiconductor laser light source having at least the active layer region and the phase control region and a distributed Bragg reflector (DBR) region, light emitted from the light semiconductor laser light source A second harmonic generation device for generating a second harmonic from the first harmonic generation device, and means for detecting an optical output from the second harmonic generation device, the optical output of the semiconductor laser light source being in a low output state and a high output state A method of controlling a light source device that switches between at least two states, wherein the semiconductor laser light source is in a high output state and the wavelength of the emitted light from the semiconductor laser light source is set to the optimum wavelength of the second harmonic generation device. performs calibration for, then, the semiconductor laser light source is in the high output state, a calibration for the light output to the control target value from the second harmonic generation device, before The semiconductor laser light source is in the low output state, and wherein the calibration and sequentially performing for the light output to the control target value from the second harmonic generation device.

Further, in the above control method of the light source apparatus of the present invention, the calibration of the wavelength of the emitted light to the optimum wavelength of the second harmonic generation device of the semiconductor laser light source, the said phase control region DBR region It is preferable to adjust the amount of current injected into the.

Further, the in the control method of the light source apparatus of the present invention, the calibration for the light output to the control target value from the second harmonic generation device, the current injected into the said active layer region phase adjustment region It is preferable to adjust the amount.

  According to the present invention, the laser power calibration process can be completed without performing a retry process.

  Hereinafter, the present invention will be described more specifically using embodiments.

  FIG. 1 is a schematic configuration diagram showing a light source device according to an embodiment of the present invention.

  As shown in FIG. 1, in the light source device of this embodiment, as a semiconductor laser light source used as a fundamental wave, a distributed Bragg reflector (hereinafter referred to as “DBR”) region 1 and light in the laser by injection current are used. A 0.85 μm band 100 mW class AlGaAs wavelength tunable DBR semiconductor laser light source 4 having a phase adjustment region 2 for adjusting the phase of the light source and an active layer region 3 for controlling the output power by an injection current is used.

As the second harmonic generation device, a quasi phase matching (hereinafter referred to as “QPM”) optical waveguide type second harmonic generation (hereinafter referred to as “SHG”) device (optical waveguide type QPM-SHG device). 5 is used. That is, the optical waveguide type QPM-SHG device 5 has an optical waveguide 12 formed on the upper surface of an optical crystal substrate (0.5 mm thick X plate MgO-doped LiNbO ₃ substrate) 11 using lithium niobate (LiNbO ₃ ). And a periodic domain-inverted region orthogonal to the optical waveguide 12 for compensating for the propagation constant difference between the fundamental wave and the harmonic. The optical waveguide 12 is formed by proton exchange in pyrophosphoric acid. The periodic domain-inverted region is formed by forming a comb-shaped electrode on the X-plate MgO-doped LiNbO ₃ substrate 11 and applying an electric field. The optical waveguide type QPM-SHG device 5 can use a large nonlinear optical constant, and is an optical waveguide type, and can have a long interaction length, so that high conversion efficiency can be realized. it can.

The semiconductor laser light source 4 and the optical waveguide type QPM-SHG device 5 are integrated on the Si submount 6, and the temperature is controlled by a Peltier element. The semiconductor laser light, which is fundamental wave light, is coupled to the optical waveguide 12 of the optical waveguide type QPM-SHG device 5 by direct coupling without using a lens. That is, the fundamental wave light emitted from the semiconductor laser light source 4 is incident on the optical waveguide type QPM-SHG device 5, and the fundamental wave light incident on the optical waveguide type QPM-SHG device 5 is confined inside the optical waveguide 12. Propagate. The fundamental light propagating in the optical waveguide 12 is converted into the second harmonic by the non-linearity of the optical crystal (X plate MgO-doped LiNbO ₃ ). Harmonic light having a wavelength of 1 is emitted.

The optical waveguide type QPM-SHG device 5 having the above structure has a wavelength as shown in FIG. 2 with respect to the wavelength of the incident fundamental wave light due to the wavelength dispersion characteristic of the optical crystal (X plate MgO-doped LiNbO ₃ ). Has characteristics. FIG. 2 shows the output power of the harmonic light emitted with respect to the wavelength of the incident fundamental wave light. The harmonic light has an output characteristic represented by a SINC function as shown in the following (Equation 1) with respect to the wavelength λ of the fundamental wave light with the optimum wavelength λ0 of the fundamental wave light as a peak.
[Equation 1]
y = Sinc {(λ−λ0) × π / a}
= Sin {(λ−λ0) × π / a} / {(λ−λ0) × π / a}
Here, the wavelength tolerance expressed by the wavelength width at which the harmonic output power becomes half of the maximum value has a width of about 0.1 nm, and in order to obtain a stable blue output, the wavelength of the fundamental wave light is changed. It is necessary to control to λ0 accurately and stably.

  Hereinafter, a method for controlling the oscillation wavelength of the semiconductor laser light source 4 shown in FIG. 1 will be described.

In a semiconductor laser light source, in general, only light having a wavelength λ satisfying the following (Equation 2) is excited with respect to the optical distance L between the front and rear reflecting surfaces.
[Equation 2]
2L = nλ (n: integer)
A column of wavelengths λ that satisfies the above (Formula 2) is called a “longitudinal mode”, and the oscillation wavelength in this case takes discrete values. In the semiconductor laser light source 4 shown in FIG. 1, a phase adjustment region 2 is provided between the DBR region 1 and the emission end face of the semiconductor laser light source 4, and the semiconductor laser light source 4 is supplied by a current applied to the phase adjustment region 2. The wavelength λ of the longitudinal mode can be changed by changing the optical distance L. Thus, the oscillation wavelength of the semiconductor laser light source 4 can be controlled by the current applied to the phase adjustment region 2.

However, in this wavelength control method, the wavelength control range is limited for the reasons described below. That is, a grating is formed in the DBR region 1 of the semiconductor laser light source 4 shown in FIG. 1, and only light having a wavelength defined by the period is reflected. Specifically, when the refractive index of the DBR region 1 is n _dbr and the grating period of the DBR region 1 is Λ, the wavelength range of light that can be reflected by the DBR region 1 is about 2Λ / n _dbr ± 0.1 nm. Therefore, only wavelength control within this range can be performed.

  In the present embodiment, the following method is adopted to expand the wavelength control range. That is, an electrode is formed in the DBR region 1, and an effective grating period of the DBR region 1 is changed and an optimum wavelength in the DBR region 1 is changed by a current applied to the electrode. The oscillation wavelength can be continuously controlled by changing the optimum wavelength of the DBR region 1 so as to follow the change of the wavelength of the longitudinal mode due to the current applied to the phase adjustment region 2. Actually, a constant ratio of current is applied to the DBR region 1 and the phase adjustment region 2.

FIG. 3 is a block diagram showing a control circuit of the light source device in one embodiment of the present invention. In FIG. 3, reference numeral 300 denotes a wavelength tunable DBR semiconductor laser light source as a semiconductor laser light source. The wavelength tunable DBR semiconductor laser light source 300 includes a light emitting portion (active layer region) 301, a phase variable portion (phase adjustment region) 302, and a wavelength. The variable part (DBR area) 303 is configured. Reference numeral 304 denotes a waveguide type QPM-SHG device as a second harmonic generation device, and a second harmonic output from the waveguide type QPM-SHG device 304 is detected by a photodetector 305. The detection result of the second harmonic output is fed back to the optical output / wavelength control means 340 as the monitor voltage FS _mon by the I / V amplifier 306.

The light emitting unit 301 of the wavelength tunable DBR semiconductor laser light source 300 is driven by a light emitting unit drive current source 310. Here, the light emitting unit driving current source 310 includes a peak current source 311, a bias current source 312, and a DC current source 313. The current values of the peak current source 311, the bias current source 312 and the DC current source 313 are set by the optical output / wavelength control means 340 at I _op PK, I _op BS, and I _op DC, respectively.

The phase variable unit 302 of the wavelength tunable DBR semiconductor laser light source 300 is driven by a phase variable unit drive current source 320. Here, the phase variable portion drive current source 320 is configured by a peak current source 321, a bias current source 322, and a DC current source 323. The current values of the peak current source 321, the bias current source 322, and the DC current source 323 are set by the optical output / wavelength control means 340 as I _ph PK, I _ph BS, and I _ph DC, respectively. Then, the peak current source 321 and the bias current source 322 are respectively switched by the modulation signals PKMD and BSMD from the recording waveform generating means 350, whereby the light output modulation of the wavelength tunable DBR semiconductor laser light source 300 is realized at high speed.

  Hereinafter, the operation of the phase variable unit driving current source 320 will be described. During the recording operation, the current injected into the light emitting unit 301 naturally increases because of modulation with high laser power, but the temperature of the light emitting unit 301 rises due to heat generation at that time. Since the light emitting unit 301 also has a waveguide structure, a change in refractive index due to heat generation causes a phase and wavelength shift. As a result, the conversion efficiency and mode hopping of the optical waveguide type QPM-SHG device 304 occur. In order to prevent this, in the present embodiment, a current substantially in reverse phase to that injected into the light emitting unit 301 is supplied to the phase variable unit 302 by the phase variable unit drive current source 320. That is, first, the inversion means 360 inverts the modulation signals PKMD and BSMD from the recording waveform generation means 350 to modulate the peak current source 321 and the bias current source 322. As a result, as shown in FIG. 4, while the current injected into the light emitting unit 301 increases, the current injected into the phase variable unit (heater) 302 decreases, and as a whole, the amount of generated heat is Regardless of the erase operation or playback operation, it is kept constant.

The wavelength tunable unit 303 of the wavelength tunable DBR semiconductor laser light source 300 is driven by the wavelength tunable unit driving current source 330, and the current value of the wavelength tunable unit driving current source 330 is changed to optimize the wavelength tunable DBR semiconductor laser light source 300. The oscillation wavelength can be changed. The current value of the wavelength variable portion drive current source 330 is set by I _dbr by the light output / wavelength control means 340.

  FIG. 5 is a block diagram showing in detail the light output / wavelength control means 340 of FIG. As shown in FIG. 5, the light output / wavelength control means 340 includes a register block 520, a preset value storage unit 510, and a light output / wavelength control unit 530. Here, the register block 520 is for setting the current value of each current source.

During the recording operation, I _op DC, I _op BS, and I _op PK are determined so as to realize desired bottom power, bias power, and peak power for the light emitting unit driving current source 310. Here, I _op DC is defined by the following (Equation 3).
[Equation 3]
I _op DC = I _op BM + ΔI _op
In the above (Equation 3), I _op BM of the first item on the right side is determined so as to realize bottom power. Note that ΔI _{op of} the second item on the right side is a light output control component by the light output / wavelength control unit 530.

Further, for the phase variable unit driving current source 320, I _ph PK is defined by the following ( _Equation 4) and is determined so as to cancel the wavelength change due to the operation of the peak current source 311 of the light emitting unit driving current source 310. The
[Equation 4]
I _ph PK = β ₃ × I _op PK
For the phase variable unit driving current source 320, I _ph BS is defined by the following ( _Equation 5), and is determined so as to cancel the wavelength change due to the operation of the bias current source 312 of the light emitting unit driving current source 310. The
[Equation 5]
I _ph BS = β ₂ × I _op BS
For the phase variable unit drive current source 320, I _ph DC is defined by the following ( _Equation 6).
[Equation 6]
I _ph DC = I _ph MAIN−γ ₃ × β ₃ × I _op PK
-Γ ₂ × β ₂ × I _op BS-β ₁ × ΔI _op + ΔI _ph
In the above (Equation 6), I _ph MAIN of the first item on the right side is determined so that the wavelength of the tunable DBR semiconductor laser light source 300 becomes the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. Note that γ ₃ × β ₃ × I _op PK in the second item on the right side indicates that the wavelength of the wavelength tunable DBR semiconductor laser light source 300 indicates the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304 when I _op PK is increased or decreased. It is a component that changes I _ph DC so as to follow. Also, γ ₂ × β ₂ × I _op BS in the third item on the right side indicates that the wavelength of the tunable DBR semiconductor laser light source 300 increases the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304 when I _op BS is increased or decreased. It is a component that changes I _ph DC so as to follow. The fourth item on the right side, β ₁ × ΔI _op, is the wavelength of the tunable DBR semiconductor laser light source 300 when the light output control component ΔI _op by the light output / wavelength control unit 530 is increased or decreased. This is a component that changes I _op DC so as to follow the maximum efficiency wavelength of the device 304. Further, ΔI _{ph of} the fifth item on the right side is a component that changes I _ph DC during wavelength control.

Further, I _dbr is defined by the following ( _Equation 7) for the wavelength variable portion drive current source 330.
[Equation 7]
I _dbr = I _dbr IN + α × ΔI _ph
In the above ( _Equation 7), I _dbr IN of the first item on the right side is determined so that the wavelength of the wavelength tunable DBR semiconductor laser light source 300 becomes the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. The second item α × ΔI _ph on the right side is a component that changes I _dbr and ΔI _ph at a constant ratio α so that the wavelength can be continuously varied when ΔI _ph is changed during wavelength control.

In the reproducing operation, I _op DC is defined by the following (Equation 8) with respect to the light emitting unit driving current source 310.
[Equation 8]
I _op DC = I _op BM + ΔI _op + I _op RD
In the above (Equation 8), I _op BM of the first item on the right side and ΔI _{op of} the second item on the right side are determined in the same manner as in the recording operation. The third item I _op RD on the right side is determined so as to realize read power.

For the phase variable unit drive current source 320, I _ph PK and I _ph BS are defined in the same manner as in the recording operation.

Further, I _ph DC is defined by the following ( _Equation 9) with respect to the phase variable unit driving current source 320.
[Equation 9]
I _ph DC = I _ph MAIN−γ ₃ × β ₃ × I _op PK
-Γ ₂ × β ₂ × I _op BS-β ₁ × ΔI _op
+ ΔI _ph -β ₁ × I _op RD
In the above (Equation 9), the first item to the fifth item on the right side are determined in the same manner as in the recording operation. Further, β ₁ × I _op RD of the sixth item on the right side is such that the wavelength of the tunable DBR semiconductor laser light source 300 follows the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304 when I _op RD is increased or decreased. It is a component that changes I _ph DC.

Further, I _dbr is defined in the same manner as in the recording operation for the wavelength variable portion drive current source 330.

The respective current values I _op PK, I _op BS, I _op BM, I _op RD, I _ph MAIN, I _dbr IN and the respective parameters α, β ₁ , β ₂ , β ₃ , γ ₂ , γ ₃ are The wavelength tunable DBR semiconductor laser light source 300 is adjusted in the manufacturing process of the light source device so as to emit light with a desired light output. The values at that time are I _op PK (pr), I _op BS (pr), I _op BM (pr), I _op RD (pr), I _ph MAIN (pr), I _dbr IN (pr), respectively. , Α (pr), β ₁ (pr), β ₂ (pr), β ₃ (pr), γ ₂ (pr), γ ₃ (pr) are stored in the preset value storage unit 510. These values are used for “startup laser processing” and “initial laser power calibration processing” described later.

The optical output / wavelength control unit 530 is configured so that the wavelength tunable DBR semiconductor laser light source 300 always emits light with a desired optical output according to the monitor voltage FS _mon fed back from the I / V amplifier 306 (FIG. 3). Control the current value.

As shown in FIGS. 3 and 5, the optical output / wavelength control unit 340 operates with respect to the light emitting unit driving current source 310, the phase variable unit driving current source 320, and the wavelength variable unit driving current source 330. Enable signals CE_I _op , CE_I _ph , and CE_I _dbr are output.

  Next, when starting the light source device of the present invention, a startup procedure (hereinafter referred to as the following) for causing the oscillation wavelength of the tunable DBR semiconductor laser light source 300 to reach the maximum efficiency wavelength of the waveguide type QPM-SHG device 304 in a short time And a method of performing calibration (hereinafter referred to as “initial laser power calibration process”) for causing the wavelength-variable DBR semiconductor laser light source 300 to emit light with a desired light output in a short time. .

<Laser processing at startup>
When the light source device is activated, each register of the register block 520 of the light output / wavelength control unit 340 shown in FIG. 5 has a preset value stored in the preset value storage unit 510: I _op PK (pr), I _op BS (pr), I _op BM (pr), I _op RD (pr), I _ph MAIN (pr), I _dbr IN (pr), α (pr), β ₁ (pr), β ₂ (pr ), Β ₃ (pr), γ ₂ (pr), γ ₃ (pr) are stored. Note that the current value of each current source is determined by a value calculated from these preset values.

In the start-up laser processing, the light emitting unit driving current source 310, the phase variable unit driving current source 320, and the wavelength variable unit driving current source 330 are first configured to perform optical output / wavelength control, as shown in FIGS. Enable signals CE_I _op , CE_I _ph and CE_I _dbr are received from the means 340, respectively. The light emitting unit driving current source 310 receives the enable signal CE_I _op and starts driving at a preset current value at the time of the reproduction operation expressed by the following (Equation 10).
[Equation 10]
I _op DC = I _op BM (pr) + I _op RD (pr)
Furthermore, the phase variable parts drive current source 320, upon receiving an enable signal CE_I _ph, starts driving at the preset current value during reproduction operation, which is denoted by the following equation (11).
[Equation 11]
I _ph DC = I _ph MAIN (pr)
−γ ₃ (pr) × β ₃ (pr) × I _op PK (pr)
−γ ₂ (pr) × β ₂ (pr) × I _op BS (pr)
−β ₁ (pr) × I _op RD (pr)
In addition, the wavelength variable unit driving current source 330 receives the enable signal CE_Idbr, and at the same time starts driving with a preset current value expressed by the following ( _Equation 12).
[Equation 12]
I _dbr = I _dbr IN (pr)
As described above, in the startup laser processing, each current source is adjusted so that the wavelength tunable DBR semiconductor laser light source 300 emits light with a desired light output when the light source device is manufactured, and the preset value storage unit 510 stores the light source device. The driving is started at the preset current value stored (that is, predetermined). The maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304 is always longer than the oscillation wavelength of the tunable DBR semiconductor laser light source 300 at room temperature. When current injection into the wavelength tunable DBR semiconductor laser light source 300 is started from the room temperature, the temperatures of the light emitting unit 301, the phase variable unit 302, and the wavelength variable unit 303 are increased by the injected current, thereby the light emitting unit 301, The refractive indexes of the phase variable unit 302 and the wavelength variable unit 303 change, and the oscillation wavelength of the wavelength variable DBR semiconductor laser light source 300 changes to the longer wavelength side. As shown in FIG. 7, this wavelength change depends on the temperature rise, shows a transient response characteristic of a first-order lag system, and is almost settled after a fixed time.

After startup laser processing, initial laser power calibration processing is performed, and I _dbr wavelength exploration processing is _performed so that the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 is approximately equal to the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. Do.

In the I _dbr wavelength exploration process, the injection current I _dbr to the wavelength variable unit (DBR region) 303 is sequentially changed within a predetermined range, and the injection when the increase in the detected value of the optical output corresponding to the sequential change is maximized. The current value I _dbr _ll and the injection current value I _dbr _ul when the decrease in the detected value of the optical output is maximized are obtained, and the injection currents into the wavelength variable unit (DBR region) 303 are _expressed as I _dbr _ll and I _dbr. Decide on a value between _ul.

Preset values are set so that the injection current values I _dbr _ll and I _dbr _ul are always included in the predetermined range when the injection current I _dbr to the wavelength variable portion (DBR region) 303 is sequentially changed in the predetermined range. Is set. If the injection current values I _dbr _ll and I _dbr _ul are not included in the predetermined range, the I _dbr wavelength exploration process must be performed again by changing the range in which I _dbr is changed (“retry processing”). )), Leading to a significant loss of startup time.

By initiating the injection of current in the preset current value, since the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 can be made substantially equal to the maximum efficiency the wavelength of the optical waveguide type QPM-SHG device 304, once the I _dbr wavelength A wavelength almost equal to the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304 can be reliably obtained by the exploration process.

  In the above description, in the startup laser processing, the phase variable unit drive current source 320 starts driving at the preset current value at the time of the reproduction operation expressed by the above (Equation 11). However, as shown in FIG. 8, the DC current source 323 of the phase variable unit driving current source 320 first starts to drive at a current value larger than the preset current value expressed by the above (Equation 11), for a predetermined time. By switching to the preset current value expressed by the above (Equation 11) after the lapse of time, the settling time of the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 can be shortened, and the wavelength search processing can be quickly switched. This makes it possible to shorten the startup time.

Also, as shown in FIG. 9, after the light source device is started, if the phase variable unit driving current source 320 and the wavelength variable unit driving current source 330 are operated before the startup laser processing, that is, the phase variable. If the unit driving current source 320 and the wavelength variable unit driving current source 330 receive the enable signals CE_I _ph and CE_I _dbr respectively, and the light emitting unit driving current source 310 receives the enable signal CE_I _op after a predetermined time has elapsed, Since the settling time of the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 can be shortened and it is possible to quickly switch to the wavelength exploration processing, the start-up time can be shortened.

<Initial laser power calibration process>
The light source device performs an initial laser power calibration process after a predetermined time has elapsed since activation. In the initial laser power calibration process, the current values I _op PK, I _op BS, I _op BM, I _op RD, I _ph are set so that the wavelength tunable DBR semiconductor laser light source 300 can emit light with a desired light output. This is a process for _obtaining MAIN and I _dbr IN. In the initial laser power calibration process, the following process is performed. First, an I _dbr wavelength exploration process is performed. This optimizes the current value I _dbr of the wavelength variable portion drive current source 330 in order to make the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 approximate to the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. In other words, it is a rough adjustment of the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300. Next, an I _ph MAIN wavelength search process is performed. This is to optimize the value of I _ph MAIN in order to set the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 to the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304, so to speak, a wavelength tunable DBR semiconductor. This is a fine adjustment of the oscillation wavelength of the laser light source 300. Next, recording power calibration and reproduction power calibration are performed. Recording power calibration includes bottom power calibration, bias power calibration, and peak power calibration. In the bottom power calibration, the current value of I _op BM is calibrated so that a desired bottom power is obtained. In the bias power calibration, the current value of I _op BS is obtained so that a desired bias power is obtained. In the peak power calibration, the current value of I _op PK is calibrated so that a desired peak power can be obtained. Here, the light intensity detection means for recording power calibration will be described in detail.

  In the recording operation, as shown in FIG. 10, the peak current source and the bias current source are switched at high speed, and the laser light intensity is modulated at high speed between the peak power and the bottom power, and as shown in FIG. In addition, the operation of constantly turning on only the bias current source and setting the laser light intensity to a constant bias power is repeated. As a result, a mark is formed when the light intensity is modulated at high speed between the peak power and the bottom power, and the mark is erased when the light intensity is set to a constant bias power. ”).

Here, the “mark portion average value detection” is to obtain the average value of the monitor voltage FS _mon obtained when the photodetector 305 receives light having the light intensity when high-speed modulation is performed between the peak power and the bottom power. And obtaining the monitor voltage FS _mon obtained when the photodetector 305 receives light of bias power is called “space portion detection”.

  After that, when you want to obtain the light intensity when high-speed modulation between peak power and bottom power, such as during peak power calibration, perform mark part average value detection, and when you want to obtain bias power, such as during bias power calibration, Perform space detection.

After the above recording power calibration is performed, the reproduction power calibration is performed. This calibrates the current value of I _op RD so that a desired read power can be obtained. Through the above processing, a desired light output can be obtained.

When starting the initial laser power calibration process, the current values of the respective current sources are set to respective preset values: I _op stored in the respective registers of the register block 520 of the optical output / wavelength control means 340 shown in FIG. PK (pr), I _op BS (pr), I _op BM (pr), I _op RD (pr), I _ph MAIN (pr), I _dbr IN (pr), α (pr), β ₁ (pr) , Β ₂ (pr), β ₃ (pr), γ ₂ (pr), and γ ₃ (pr).

  Further, when starting the initial laser power calibration process, each current source uses a test pattern as shown in FIG. 10 (hereinafter referred to as “test pattern 1”), which is close to the driving mode during the recording operation. Drive mode is used.

(I _dbr wavelength exploration process)
First, I _dbr wavelength exploration processing is performed. As shown in FIG. 11, in this I _dbr wavelength exploration process, the value of I _dbr IN is changed stepwise. When the value of I _dbr IN is changed stepwise, the oscillation mode of the wavelength tunable DBR semiconductor laser light source 300 changes. At this time, a change in the monitor voltage FS _mon (see FIG. 3) fed back from the I / V amplifier 306 is detected. Based on the detection result, a value of I _dbr IN is determined so that the oscillation wavelength in the oscillation mode of the tunable DBR semiconductor laser light source 300 at that time is approximately close to the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304 (hereinafter, this The oscillation mode is called “optimal mode”). At the same time, the center value of I _dbr IN is _obtained so as not to hop from the optimum mode.

The center value changing the _{I dbr IN I dbr IN (pr} ), range I _dbr IN changing the I _dbr IN (amp), to the variation of I _dbr IN in one step and [Delta] I _dbr IN. Here, a typical value of I _dbr IN required to change the oscillation mode of the wavelength tunable DBR semiconductor laser light source 300 by one mode is defined as I _dbr IN (1 mode). Then, I _dbr IN (amp), which is a range in which I _dbr IN is changed, is sufficiently larger than I _dbr IN (1 mode) so that the optimum mode can be always obtained when the I _dbr wavelength search process is performed. Must be big. At the same time, ΔI _dbr IN must be sufficiently small with respect to I _dbr IN (1 mode) so that the center value of I _dbr IN that is not mode- _hopped from the optimal mode can be obtained.

Hereinafter, the procedure of the I _dbr wavelength exploration process will be described in more detail using the flowchart shown in FIG. 12 with reference to FIG.

  Initially, each current source has a driving configuration close to the driving configuration during the recording operation by using test pattern 1 (FIG. 10) (S1).

In this state, first, the current value I _dbr IN of the wavelength variable unit driving current source 330 is set to I _dbr IN (0) expressed by the _following ( _Equation 13), and the wavelength variable unit 303 of the wavelength variable DBR semiconductor laser light source 300 is set. Drive (S2).
[Equation 13]
I _dbr IN (0) = I _dbr IN (pr)
-I _dbr IN (amp) / 2
Then, the average value of the optical output of the wavelength tunable DBR semiconductor laser light source 300 at this time is detected, and the monitor voltage at that time is FS _mon (0). Next, the value of I _dbr IN is increased by ΔI _dbr IN per step, the average value of the optical output of the wavelength tunable DBR semiconductor laser light source 300 is detected, and the monitor voltage at step t is FS _mon (t). Here, a time change amount ΔFS _mon (t) of the monitor voltage FS _mon (t) expressed by the following (Equation 14) is obtained.
[Formula 14]
ΔFS _mon (t) = FS _mon (t) −FS _mon (t−1)
The above process is repeated until I _dbr IN is below is denoted by (number _{15) I dbr IN (t)} (S3).
[Equation 15]
I _dbr IN (t) = I _dbr IN (pr)
+ I _dbr IN (amp) / 2
When I _dbr IN is changed in this way, as shown in FIG. 11, when the oscillation mode of the wavelength tunable DBR semiconductor laser 300 reaches the optimum mode for the first time, the increase is maximized (ΔFS _mon (t) is In the range where the value is positive, the absolute value is the maximum). The value of I _dbr IN at this time is the lower limit of I _dbr IN that does not mode hop from the optimum mode. This value is defined as I _dbr _ll. Further, when the oscillation mode of the wavelength tunable DBR semiconductor laser 300 is mode-hopped from the optimum mode to the next mode, the decrease is maximized (the absolute value is maximum in the range where ΔFS _mon (t) is a negative value). Value). The value of I _dbr IN at this time is the upper limit of I _dbr IN that does not mode hop from the optimum mode. This value is defined as I _dbr _ul.

Here, the value of I _dbr IN is determined to be a value between I _dbr _ll and I _dbr _ul (S4). In this way, the oscillation mode of the wavelength tunable DBR semiconductor laser 300 can be selected as the optimum mode. Thereafter, the wavelength tunable unit 303 of the wavelength tunable DBR semiconductor laser light source 300 is driven with the current value I _dbr IN.

In the present embodiment, the value of I _dbr IN is determined to be a value between I _dbr _ll and I _dbr _ul, but the value of I _dbr IN is set to I _dbr _ll and I _dbr. It is desirable that the value be approximately equal to the average value of _ul. In this way, it is possible to maintain a uniform margin from both the upper and lower limits where the oscillation mode of the wavelength tunable DBR semiconductor laser 300 is not mode-hopped from the optimum mode.

(I _ph MAIN wavelength exploration process)
Next, I _ph MAIN wavelength exploration processing is performed. When the value of I _ph MAIN is changed, the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 changes. At this time, the monitor voltage FS _mon (see FIG. 3) fed back from the I / V amplifier 306 is detected as the average value of the mark portion. Based on the detection result, the value of I _ph MAIN is determined so that the oscillation wavelength of the tunable DBR semiconductor laser light source 300 at that time becomes the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304 (hereinafter, this oscillation wavelength) Is called "optimum wavelength").

The central value for changing I _ph MAIN is defined as I _ph MAIN (pr), the range for changing I _ph MAIN is defined as I _ph MAIN (amp), and the change in I _ph MAIN in one step is ΔI _ph MAIN. Here, the allowable wavelength range where the optical output of the wavelength tunable DBR semiconductor laser light source 300 is ½ of the optical output when the efficiency of the optical waveguide type QPM-SHG device 304 is the maximum efficiency is λ (1/2). a typical value for I _ph DC wavelength of the tunable DBR semiconductor laser light source 300 changes by lambda (1/2) is defined as I _ph DC (1/2) when changing the I _ph DC. Then, I _ph MAIN (amp), which is a range in which I _ph MAIN is changed, is set to I _ph DC (1/2) so that an optimum wavelength is always obtained when the I _ph MAIN wavelength search process is performed. Must be large enough. In addition, ΔI _ph MAIN must be sufficiently smaller than I _ph DC (1/2) in order to improve the detection accuracy of the optimum wavelength.

Hereinafter, the procedure of the I _ph MAIN wavelength search process will be described in more detail with reference to the flowchart shown in FIG.

  Initially, each current source has a driving configuration close to the driving configuration during the recording operation by using test pattern 1 (FIG. 10) (S5).

In this state, first, the phase variable unit 302 of the wavelength tunable DBR semiconductor laser light source 300 is set so that the current value I _ph MAIN of the phase variable unit drive current source 320 is set to I _ph MAIN (0) expressed by the following ( _Equation 16). Drive (S6).
[Equation 16]
I _ph MAIN (0) = I _ph MAIN (pr)
-I _ph MAIN (amp) / 2
Then, the average value of the optical output of the wavelength tunable DBR semiconductor laser light source 300 at the mark portion at this time is detected, and the monitor voltage at that time is FS _mon (0). Next, the value of I _ph MAIN is increased by ΔI _ph MAIN per step to detect the average value of the optical output of the wavelength tunable DBR semiconductor laser light source 300 at the mark portion, and the monitor voltage at step t is set to FS _mon (t) And

The above process is repeated until the I _ph MAIN is below I _ph MAIN (t), denoted by (number 17) (S7).
[Equation 17]
I _ph MAIN (t) = I _ph MAIN (pr)
+ I _ph MAIN (amp) / 2
When I _ph MAIN is changed in this way, FS _mon (t) becomes maximum when the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 becomes the optimum wavelength. The current value I _ph MAIN of the phase variable unit drive current source 320 is determined to be the value of I _ph MAIN at this time (S8). At this time, the optimum wavelength of the wavelength tunable DBR semiconductor laser light source 300 is selected. Thereafter, the phase variable unit 302 of the wavelength tunable DBR semiconductor laser light source 300 is driven with the current value I _ph MAIN.

As described above, the current value I _ph MAIN of the phase variable unit driving current source 320 is sequentially changed within a predetermined range, and the current value when the detected value of the optical output corresponding to the successive change is maximized is obtained. If the current value I _ph MAIN of the variable section drive current source 320 is determined to be this value, the oscillation wavelength of the tunable DBR semiconductor laser light source 300 is surely equal to the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. can do.

[Bottom power calibration]
Next, bottom power calibration is performed.

  Hereinafter, the procedure of bottom power calibration will be described in detail with reference to the flowchart shown in FIG.

  Each current source is assumed to operate normally by using test pattern 2 as shown in FIG. 14 (S21).

At the start of bottom power calibration, I _op BM is a preset value I _op BM (pr). The optical output of the wavelength tunable DBR semiconductor laser light source 300 is detected, and the monitor voltage at that time is FS _mon . Here, the control target value of the bottom power is BM _ref . Further, the error e between BM _ref and FS _mon is expressed by the following (Equation 18) (S22).
[Equation 18]
e = BM _ref -FS _mon
Then, the integral value of the error e is added to I _op BM (pr) to obtain the following (Equation 19).
[Equation 19]
I _op BM = I _op BM (pr) + Kbm × ∫edt
In (Equation 19), Kbm is a proportionality constant, and is designed so that the control characteristic of the light output is optimized.

At the same time, a value obtained by multiplying the integral value of the error e by β ₁ is subtracted from I _ph MAIN to obtain the following (Equation 20).
[Equation 20]
I _ph MAIN = I _ph MAIN−β ₁ × Kbm × ∫edt
The above processing is repeated until the error e becomes 0 (S23), the current value I _op BM emitting section drive current source 310, to determine the I _op BM in this case (S24). Thereafter, the light emitting unit 301 of the wavelength tunable DBR semiconductor laser light source 300 is driven with the current value I _op BM. At the same time, the current value I _ph MAIN of the phase variable parts drive current source 320, to determine the I _ph MAIN this time (S24). Thereafter, the light emitting unit 301 of the wavelength tunable DBR semiconductor laser light source 300 is driven with the current value I _ph MAIN.

If the above processing is performed, the wavelength change due to the addition of I _op BM can be canceled by subtraction of I _ph MAIN, so that the oscillation wavelength of the tunable DBR semiconductor laser light source 300 is always changed to the optical waveguide type QPM-SHG. A desired bottom power can be obtained while maintaining the maximum efficiency wavelength of the device 304.

[Bias power calibration]
Next, bias power calibration is performed.

  Hereinafter, the procedure of bias power calibration will be described in detail with reference to the flowchart shown in FIG.

  Each current source performs a switching operation between the bias and the bottom by using the test pattern 2 as shown in FIG. 16 (S9).

At the start of bias power calibration, I _op BS is a preset value I _op BS (pr). Only the space portion is detected from the optical output of the wavelength tunable DBR semiconductor laser light source 300, and the monitor voltage at that time is FS _mon . Here, the control target value of the bias power is assumed to be BS _ref . Further, an error e between BS _ref and FS _mon is expressed by the following (Equation 21) (S10).
[Equation 21]
e = BS _ref -FS _mon
Then, the integral value of this error e is added to I _op BS (pr) to obtain the following (Equation 22).
[Equation 22]
I _op BS = I _op BS (pr) + Kbs × ∫edt
In the above (Expression 22), Kbs is a proportionality constant, and is designed so that the control characteristic of the light output is optimized.

Along with the addition of this I _op BS, according to the calculation of the register block 520, the I _ph BS has the wavelength change of the bias current source 312 of the light emitting unit driving current source 310 as the bias current source 322 of the phase variable unit driving current source 320. The value of −β ₂ × Kbs × ∫edt is added so as to cancel out with the change in wavelength. Further, I _ph DC has a value of −γ ₂ × β ₂ × Kbs × ∫edt so that the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 follows the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. Is added.

The above processing is repeated until the error e becomes 0 (S11), the current value I _op BS emitting section drive current source 310, to determine the I _op BS at this time (S12). Thereafter, the light emitting unit 301 of the wavelength tunable DBR semiconductor laser light source 300 is driven by the current value I _op BS.

By performing the processing as described above, desired bias power is obtained by changing I _op BM while making the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 follow the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. be able to.

[Peak power calibration]
Next, peak power calibration is performed.

  Hereinafter, the procedure of peak power calibration will be described in detail with reference to the flowchart shown in FIG.

  Each current source performs switching operation between peak-bias-bottom by using test pattern 1 (FIG. 10) (S13).

At the start of peak power calibration, I _op PK is a preset value I _op PK (pr). The average value of the optical output of the tunable DBR semiconductor laser light source 300 in the mark portion is detected, and the monitor voltage at that time is FS _mon . Here, the control target value of the mark portion average value is AC _ref . Further, an error e between AC _ref and FS _mon is expressed by the following (Equation 23) (S14).
[Equation 23]
e = AC _ref −FS _mon
Then, the integral value of this error e is added to I _op PK (pr) to obtain the following (Equation 24).
[Equation 24]
I _op PK = I _op PK (pr) + Kpk × ∫edt
In the above (Equation 24), Kpk is a proportional constant, and is designed so that the control characteristic of the light output is optimized.

Along with the addition of I _op PK, according to the calculation of the register block 520, I _ph PK has a change in wavelength of the peak current source 311 of the light emitting unit driving current source 310 as a peak current source 321 of the phase variable unit driving current source 320. The value of −β ₃ × Kpk × ∫edt is added so as to cancel out with the change in wavelength. Further, I _ph DC has a value of −γ ₃ × β ₃ × Kpk × ∫edt so that the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 follows the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. Is added.

The above processing is repeated until the error e becomes 0 (S15), the current value I _op PK emitting section drive current source 310, to determine the I _op PK at this time (S16). Thereafter, the light emitting unit 301 of the wavelength tunable DBR semiconductor laser light source 300 is driven with the current value I _op PK.

When the above processing is performed, the desired peak power is obtained by changing I _op PK while making the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 follow the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. be able to.

[Reproduction power calibration]
Next, reproduction power calibration is performed.

  Hereinafter, the reproduction power calibration procedure will be described in detail with reference to the flowchart shown in FIG.

  Initially, each current source is in a driving mode during a reproducing operation by using a test pattern 3 as shown in FIG. 19 (S17).

At the start of reproduction power calibration, I _op RD is a preset value I _op RD (pr). The average value of the optical output of the tunable DBR semiconductor laser light source 300 in the mark portion is detected, and the monitor voltage at that time is FS _mon . Here, the control target value of the read power is RD _ref . Further, an error e between RD _ref and FS _mon is expressed by the following (Equation 25) (S18).
[Equation 25]
e = RD _ref −FS _mon
Then, the integral value of this error e is added to I _op RD (pr) to obtain the following (Equation 26).
[Equation 26]
I _op RD = I _op RD (pr) + Krd × ∫edt
In the above (Equation 26), Krd is a proportionality constant, and is designed so that the control characteristic of the light output is optimized.

Along with the addition of I _op RD, according to the calculation of the register block 520, I _ph DC causes the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 to follow the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. In addition, a value of −β ₁ × Krd × ∫edt is added.

The above processing is repeated until the error e becomes 0 (S19), the current value I _op RD emitting section drive current source 310, to determine the I _op RD at this time (S20). Thereafter, the light emitting unit 301 of the wavelength tunable DBR semiconductor laser light source 300 is driven with the current value I _op RD.

When the above processing is performed, the desired reproduction power is obtained by changing I _op RD while making the oscillation wavelength of the wavelength tunable DBR semiconductor laser light source 300 follow the maximum efficiency wavelength of the optical waveguide type QPM-SHG device 304. be able to.

As described above, in the present embodiment, first, the I _dbr wavelength exploration processing and the I _ph MAIN wavelength exploration processing are performed in the drive mode during the recording operation, and then the recording power calibration and the reproduction power calibration are performed. The effect is described below.

First, when the I _dbr wavelength exploration process and the I _ph MAIN wavelength exploration process are performed in the drive mode during the reproduction operation, the value of I _ph MAIN, which is the optimum wavelength, corresponds to a plurality of modes of the wavelength tunable DBR semiconductor laser light source 300. There can be more than one. Since the current supplied from the phase variable unit driving current source 320 during the recording operation to the phase variable unit 302 of the wavelength tunable DBR semiconductor laser light source 300 is lower than during the reproducing operation, the value of I _ph MAIN during the reproducing operation. Is set to a low value, the current supplied from the phase variable unit driving current source 320 to the phase variable unit 302 of the wavelength variable DBR semiconductor laser light source 300 becomes 0 mA or less, or the phase variable unit 302 A non-linear region in the low current region of the diode characteristic is reached. In such a case, a desired light output cannot be obtained. Therefore, in such a case, it is necessary to repeat the I _dbr wavelength search process, the I _ph MAIN wavelength search process, the reproduction power calibration, and the recording power calibration again by the retry process, which leads to a significant loss of start-up time.

In contrast, in the present embodiment, first, the I _dbr wavelength exploration process and the I _ph MAIN wavelength exploration process are performed in the drive mode during the recording operation, and then the recording power calibration and the reproduction power calibration are sequentially performed. Therefore, a high value necessary for the recording operation is inevitably obtained as I _ph MAIN. Therefore, the initial laser calibration process can be completed without performing the retry process.

  In addition, if the current values determined in the laser power calibration method described above are stored in the preset value storage unit 510 and used in the next startup, the startup time is further shortened. It becomes possible to do.

1 is a schematic configuration diagram showing a light source device according to an embodiment of the present invention. The figure which shows the output power of the harmonic light radiate | emitted with respect to the wavelength of the fundamental wave light in one embodiment of this invention The block diagram which shows the control circuit of the light source device in one embodiment of this invention The figure which shows the relationship between the light emission part drive current and phase variable part drive current in one embodiment of this invention Block diagram showing in detail the optical output / wavelength control means of FIG. The figure which shows the electric current application state of each current source in the laser processing at the time of starting of one embodiment of this invention The figure for demonstrating the effect of the laser processing at the time of start in one embodiment of this invention The figure which shows the other example of the electric current application state of each current source in the laser processing at the time of starting of one embodiment of this invention The figure which shows the further another example of the electric current application state of each current source in the laser processing at the time of starting of one embodiment of this invention The figure which shows the test pattern for making it the drive form close _| similar to the drive form at the time of the recording operation in the _Idbr wavelength search process of one embodiment of this invention The figure which shows the wavelength variable part drive current waveform in the _Idbr wavelength search process of one embodiment of this invention The flowchart which shows the procedure of the _Idbr wavelength search process in one embodiment of this invention The flowchart which shows the procedure of the _Iph MAIN wavelength search process in one embodiment of this invention The figure which shows the test pattern for making it operate | move normally in the bottom power calibration of one embodiment of this invention The flowchart which shows the procedure of the bottom power calibration in one embodiment of this invention The figure which shows the test pattern for making it the drive form close | similar to the drive form at the time of the recording operation in the bias power calibration of one embodiment of this invention The flowchart which shows the procedure of the bias power calibration in one embodiment of this invention The flowchart which shows the procedure of the peak power calibration in one embodiment of this invention The figure which shows the test pattern for making it the drive form at the time of reproduction | regeneration operation | movement in the read power calibration of one embodiment of this invention The flowchart which shows the procedure of the reproduction power calibration in one embodiment of this invention Schematic configuration diagram of SHG blue light source using optical waveguide type QPM-SHG device in the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DBR area | region 2 Phase adjustment area | region 3 Active layer area | region 4 Semiconductor laser light source 5,304 Optical waveguide type QPM-SHG device 11 X plate MgO doped LiNbO ₃ substrate 12 Optical waveguide 300 Wavelength variable DBR semiconductor laser light source 301 Light emitting part (active layer area) )
302 Phase variable section (phase adjustment area)
303 Wavelength tuning unit (DBR region)
305 Photodetector 306 I / V amplifier 310 Light emitting unit drive current source 311, 321 Peak current source 312, 322 Bias current source 313, 323 DC current source 320 Phase variable unit drive current source 330 Wavelength variable unit drive current source 340 Optical output / wavelength Control unit 350 Recording waveform generation unit 360 Inversion unit 510 Preset value storage unit 520 Register block 340 Optical output / wavelength control unit

Claims (3)

A semiconductor laser light source having at least an active layer region, a phase adjustment region, and a distributed Bragg reflector (DBR) region, a second harmonic generation device for generating a second harmonic from light emitted from the semiconductor laser light source, and the second Means for detecting light output from a harmonic generation device, and a method of controlling a light source device that switches the light output of the semiconductor laser light source to at least two states of a low output state and a high output state,
First, the semiconductor laser light source is a high-output state, performs Calibration for the wavelength of the emitted light of the semiconductor laser light source to the optimum wavelength of the second harmonic generation device,
Thereafter, calibration for setting the light output from the second harmonic generation device to a control target value when the semiconductor laser light source is in a high output state, and the second harmonic when the semiconductor laser light source is in a low output state. A method for controlling a light source device, comprising sequentially performing calibration for setting a light output from a wave generating device to a control target value . The semiconductor laser calibration wavelength of the emitted light to the optimum wavelength of the second harmonic generation device of the light source, to claim 1 which is performed by adjusting the amount of current injected into the said phase control region DBR region The light source device control method according to claim. The second calibration for the light output to the control target value from the harmonic generation device, a light source device according to claim 1 which is performed by adjusting the amount of current injected to the active layer region to the phase adjustment area Control method.

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