JP2768705B2 - Semiconductor laser device capable of short pulse oscillation - Google Patents
Semiconductor laser device capable of short pulse oscillationInfo
- Publication number
- JP2768705B2 JP2768705B2 JP29935688A JP29935688A JP2768705B2 JP 2768705 B2 JP2768705 B2 JP 2768705B2 JP 29935688 A JP29935688 A JP 29935688A JP 29935688 A JP29935688 A JP 29935688A JP 2768705 B2 JP2768705 B2 JP 2768705B2
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- JP
- Japan
- Prior art keywords
- laser device
- light
- semiconductor laser
- device capable
- short pulse
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Semiconductor Lasers (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は半導体レーザ装置に係わり、特に極めて短い
光パルスの発生が可能な半導体レーザ装置に関するもの
である。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device capable of generating an extremely short light pulse.
従来の短パルス発振可能なレーザ装置について、第６
図〜第８図により説明する。A conventional laser device capable of short-pulse oscillation is described in the sixth section.
This will be described with reference to FIGS.
第６図に示すように電極を分割し、一方を光軸幅部、
他方を光吸収部としたレーザ装置が知られている（例え
ば、Applide Physics Letters vol.40 No.2,15 January
1982）。図において、光増幅部の発振で発生した光は
光吸収部で吸収されて外部回路に電流が流れる。この時
の等価回路は第７図に示すようなもので、光増幅部と光
吸収部の間には内部抵抗Rpがあり、光吸収部の外部回路
には抵抗R2が接続されている。光増幅部、光吸収部のPN
接合はダイオードで表される。The electrode is divided as shown in FIG.
A laser device using the other as a light absorbing portion is known (for example, Applide Physics Letters vol.40 No.2,15 January
1982). In the figure, light generated by the oscillation of the optical amplification unit is absorbed by the light absorption unit and a current flows to an external circuit. Equivalent circuit when this is like shown in FIG. 7, between the optical amplifier and the light-absorbing portion has an internal resistance Rp, the resistor R 2 is connected to an external circuit of the light absorbing portion. PN of light amplification part and light absorption part
The junction is represented by a diode.
このように、従来の短パルス発振を行わせる半導体レ
ーザ装置は、電極の一部を分離し、その分離した部分に
負荷抵抗R2を接続し、これを介してバイアス電圧を加え
ている。この光回路はバイアス電圧V2と負荷抵抗R2を適
当に設定すると、励起電流とレーザ光出力の間にヒステ
リシスが表れる。Thus, the semiconductor laser device to perform conventional short pulse oscillation, and separating a portion of the electrode, and connect the load to the separated partial resistance R 2, are added to the bias voltage through this. This optical circuit sets the bias voltage V 2 and the load resistor R 2 suitably, the hysteresis appears between the excitation current and the laser beam output.
第８図は光増幅部の励起電流I1としきい値電流の比に
対する光出力を表したものであり、第８図（ａ）はR2＝
200kΩ、パイアスV2＝20V、第８図（ｂ）はR2＝1kΩ、
バイアス電圧を1.1V、0.8Vとした時のヒステリシス特性
である。すなわち、バイアス電圧V2を加える部分のPN接
合部には増幅部のレーザダイオードで発生した自然放出
光により光電流が発生し、この電流が外部負荷抵抗R2に
流れることにより負荷抵抗の端子間電圧が増大し、その
結果、Ｐ−Ｎ接合部の電位が減少し、バンド間吸収が減
少することにより、励起電流の増化によりレーザ光が急
峻な立ち上がりをすることを示している。従って、第６
図に示すような装置により、急峻な立ち上がりのパルス
光を得ることができる。Figure 8 is a representation of the light output with respect to the ratio of the excitation current I 1 and the threshold current of the optical amplification section, Figure 8 (a) is R 2 =
200 kΩ, Pias V 2 = 20 V, FIG. 8 (b) shows R 2 = 1 kΩ,
This is a hysteresis characteristic when the bias voltage is set to 1.1 V and 0.8 V. That is, the PN junction portion applying a bias voltage V 2 photoelectric current is generated by spontaneous emission light generated in the laser diode of the amplifier, between the load resistor terminal by flowing the current to the external load resistance R 2 The voltage increases, as a result, the potential at the PN junction decreases, and the interband absorption decreases, indicating that the laser light rises sharply due to an increase in the excitation current. Therefore, the sixth
With the device as shown in the figure, a pulse light having a steep rising can be obtained.
しかしながら、第６図に示すようなレーザ装置におい
ては、光吸収部のダイオードの両端にかかる電圧の変化
によって吸収率が変化することを利用しているため、第
９図の等価回路で示すように、ダイオードの有する容量
（C2）のために電圧の過渡応答は時定数τ＝C2R2でしか
応答しない。従って、外部回路に負荷抵抗を接続する従
来の方法では、極めて急峻な立ち上がりのパルスを得る
ことができないという問題があった。However, the laser device shown in FIG. 6 utilizes the fact that the absorptance changes due to the change in the voltage applied to both ends of the diode in the light absorbing portion. Therefore, as shown in the equivalent circuit of FIG. Because of the capacitance (C 2 ) of the diode, the voltage transient response only responds with a time constant τ = C 2 R 2 . Therefore, the conventional method of connecting a load resistor to an external circuit has a problem that an extremely steep rising pulse cannot be obtained.
本発明は上記問題点を解決するためのもので、過渡応
答を飛躍的に速くすることができる半導体レーザ装置を
提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a semiconductor laser device capable of dramatically increasing a transient response.
そのために本発明は、電極を複数に分割し、一方を光
増幅部、他方を光吸収部としたタンデム電極型レーザ装
置において、該光吸収部のＰ電極とＮ電極間を短絡ある
いは低抵抗で接続したことを特徴とする。For this purpose, the present invention provides a tandem electrode type laser device in which an electrode is divided into a plurality of parts, one of which is a light amplifying part and the other is a light absorbing part. It is characterized by being connected.
本発明は、電極を複数に分割したタンデム電極型レー
ザ装置の光吸収部のダイオードを短絡あるいは極めて小
さな抵抗で接続することにより、光吸収部の過渡応答を
飛躍的に高め、短パルス発生を行わせすることができ
る。According to the present invention, the transient response of the light absorbing portion is dramatically increased by short-circuiting or connecting the diode of the light absorbing portion of the tandem electrode type laser device having a plurality of electrodes with a very small resistance, thereby generating a short pulse. It can be.
以下、実施例を図面を参照して説明する。 Hereinafter, embodiments will be described with reference to the drawings.
第１図は本発明の短パルス発振可能な半導体レーザ装
置の一実施例の構成を示す図で、図中101はタンデム電
極型レーザ、103は光増幅部、105は光吸収部を示してい
る。FIG. 1 is a diagram showing the configuration of an embodiment of a semiconductor laser device capable of short pulse oscillation according to the present invention, wherein 101 denotes a tandem electrode type laser, 103 denotes an optical amplifier, and 105 denotes a light absorbing unit. .
光増幅部103はバイアス電圧V1、光吸収部105はバイア
ス電圧V2が加えられ、両者間は内部抵抗Rpで接続された
形となっている。The bias voltage V 1 is applied to the light amplification unit 103 and the bias voltage V 2 is applied to the light absorption unit 105, and the two are connected by an internal resistor Rp.
第１図の等価回路は第２図に示すように、光増幅部10
3、光吸収部105のダイオードの間が内部抵抗Rpで接続さ
れ、それぞれバイアス電圧V1、V2がかけられた形となっ
ている。なお、光吸収部105のダイオードは短絡され、
第３図に示すようになっている。しかし、実際にはダイ
オードは内部抵抗を有しているため、第４図に示すよう
な等価回路で表される。ここでR0はダイオード内部の抵
抗、Ｃはダイオードの浮遊容量である。ダイオードの内
部抵抗の値は、通常、非常に小さく10Ω以下であり、そ
のため光増幅部からの光を吸収して光電流が流れても、
ダイオードの接合部の端子間電圧はほとんど変化しない
と言ってよい。The equivalent circuit of FIG. 1 is, as shown in FIG.
3. The diodes of the light absorbing unit 105 are connected by the internal resistance Rp, and are applied with bias voltages V 1 and V 2 , respectively. In addition, the diode of the light absorption unit 105 is short-circuited,
As shown in FIG. However, since a diode actually has an internal resistance, it is represented by an equivalent circuit as shown in FIG. Here, R0 is the resistance inside the diode, and C is the stray capacitance of the diode. The value of the internal resistance of the diode is usually very small, 10Ω or less, so even if the photocurrent flows by absorbing light from the optical amplifier,
It can be said that the voltage between the terminals of the junction of the diode hardly changes.
次に本発明の原理を第５図により説明する。 Next, the principle of the present invention will be described with reference to FIG.
第５図は光吸収部のエネルギーバンド構造を示してい
る。FIG. 5 shows the energy band structure of the light absorbing portion.
今、光増幅部103からの光が入射して光吸収部で吸収
されるとその励起によりキャリアが発生し、発生した電
子と正孔はそれぞれＮ型領域とＰ型領域に流れていく。
その過渡応答時間は接合部の空乏層の厚さと電子と正孔
の伝播速度によって決まるが、通常10ps〜数psの時間を
要する。逆にいえば、これよりも短い時間領域では電子
と正孔の応答が追随できず、この間、光吸収係数が減少
することになる。従って、非常に短時間の間では吸収係
数が減少し、その間レーザ発振が生じ、パルス発振を行
わせることができる。Now, when light from the optical amplification unit 103 enters and is absorbed by the light absorption unit, carriers are generated by the excitation, and the generated electrons and holes flow to the N-type region and the P-type region, respectively.
The transient response time is determined by the thickness of the depletion layer at the junction and the propagation speed of electrons and holes, but usually takes 10 ps to several ps. Conversely, in a shorter time period, the response of electrons and holes cannot follow, and during this time, the light absorption coefficient decreases. Therefore, in a very short time, the absorption coefficient decreases, and during that time, laser oscillation occurs, and pulse oscillation can be performed.
以上のように本発明によれば、タンデム電極型レーザ
装置において、光吸収部の接合部の電極を短絡あるいは
非常に小さな抵抗で接続することにより、非常に短いパ
ルスの発生が可能となる。As described above, according to the present invention, in a tandem electrode type laser device, an extremely short pulse can be generated by short-circuiting or connecting an electrode at a junction of a light absorbing portion with a very small resistance.
従って、このような短パルス光を距離測定やレーザレ
ーダー等への応用、あるいは入力光パルスによるトリガ
が可能な高速光−光ゲートとしても利用可能である。Therefore, such a short pulse light can be applied to a distance measurement, a laser radar, or the like, or can be used as a high-speed light-light gate capable of being triggered by an input light pulse.
第１図は本発明の半導体レーザ装置の構成を示す図、第
２図は第１図の等価回路を示す図、第３図は光吸収部の
ダイオードの短絡を示す図、第４図はPN接合部の等価回
路図、第５図は光吸収部のエネルギバンド構造を示す
図、第６図〜第８図は従来の短パルス発生可能なレーザ
装置を示す図、第９図は等価回路図である。 101……タンデム電極型レーザ、103……光増幅部、105
……光吸収部。1 is a diagram showing a configuration of a semiconductor laser device of the present invention, FIG. 2 is a diagram showing an equivalent circuit of FIG. 1, FIG. 3 is a diagram showing a short circuit of a diode in a light absorbing portion, and FIG. FIG. 5 is a diagram showing an energy band structure of the light absorbing portion, FIGS. 6 to 8 are diagrams showing a conventional laser device capable of generating a short pulse, and FIG. 9 is an equivalent circuit diagram. It is. 101 …… Tandem electrode type laser, 103 …… Optical amplifier, 105
...... Light absorption part.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 島田 潤一 茨城県つくば市梅園１丁目１番４ 工業 技術院電子技術総合研究所内 (72)発明者 下山 謙司 茨城県牛久市東猯穴町1000番地 三菱化 成株式会社総合研究所内 (72)発明者 後藤 秀樹 茨城県牛久市東猯穴町1000番地 三菱化 成株式会社総合研究所内 審査官 小原 博生 (56)参考文献 特開 昭63−84182（ＪＰ，Ａ) 特開 平１−239986（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) H01S 3/18────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Shimada 1-1-4 Umezono, Tsukuba, Ibaraki Pref. Inside the Research Institute of Electronics and Technology (72) Inventor Kenji Shimoyama 1000, Higashinaiana-cho, Ushiku-shi, Ibaraki Mitsubishi (72) Inventor Hideki Goto 1000, Higashikanamachi, Ushiku-shi, Ibaraki Pref. Hiroshi Ohara, Examiner, Mitsubishi Chemical Research Institute (56) References JP-A-63-84182 (JP, A JP-A 1-239986 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) H01S 3/18
Claims (1)
方を光吸収部としたタンデム電極型レーザ装置におい
て、該光吸収部のＰ電極とＮ電極間を短絡あるいは低抵
抗で接続したことを特徴とする短パルス発振可能な半導
体レーザ装置。1. A tandem electrode type laser device in which an electrode is divided into a plurality of parts, one of which is a light amplifying part and the other is a light absorbing part, wherein a P electrode and an N electrode of the light absorbing part are connected with a short circuit or low resistance. A semiconductor laser device capable of short-pulse oscillation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29935688A JP2768705B2 (en) | 1988-11-25 | 1988-11-25 | Semiconductor laser device capable of short pulse oscillation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29935688A JP2768705B2 (en) | 1988-11-25 | 1988-11-25 | Semiconductor laser device capable of short pulse oscillation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02144982A JPH02144982A (en) | 1990-06-04 |
| JP2768705B2 true JP2768705B2 (en) | 1998-06-25 |
Family
ID=17871497
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29935688A Expired - Lifetime JP2768705B2 (en) | 1988-11-25 | 1988-11-25 | Semiconductor laser device capable of short pulse oscillation |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2768705B2 (en) |
-
1988
- 1988-11-25 JP JP29935688A patent/JP2768705B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02144982A (en) | 1990-06-04 |
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