RU2700343C1 - Laser emitter with controlled interferometer as output mirror - Google Patents

Laser emitter with controlled interferometer as output mirror Download PDF

Info

Publication number
RU2700343C1
RU2700343C1 RU2018146379A RU2018146379A RU2700343C1 RU 2700343 C1 RU2700343 C1 RU 2700343C1 RU 2018146379 A RU2018146379 A RU 2018146379A RU 2018146379 A RU2018146379 A RU 2018146379A RU 2700343 C1 RU2700343 C1 RU 2700343C1
Authority
RU
Russia
Prior art keywords
laser
resonator
switching
michelson interferometer
optical
Prior art date
Application number
RU2018146379A
Other languages
Russian (ru)
Inventor
Николай Анатольевич Грязнов
Евгений Николаевич Соснов
Дмитрий Алексеевич Горячкин
Виктория Михайловна Никитина
Original Assignee
Федеральное государственное автономное научное учреждение "Центральный научно-исследовательский и опытно-конструкторский институт робототехники и технической кибернетики" (ЦНИИ РТК)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Федеральное государственное автономное научное учреждение "Центральный научно-исследовательский и опытно-конструкторский институт робототехники и технической кибернетики" (ЦНИИ РТК) filed Critical Федеральное государственное автономное научное учреждение "Центральный научно-исследовательский и опытно-конструкторский институт робототехники и технической кибернетики" (ЦНИИ РТК)
Priority to RU2018146379A priority Critical patent/RU2700343C1/en
Application granted granted Critical
Publication of RU2700343C1 publication Critical patent/RU2700343C1/en

Links

Images

Abstract

FIELD: laser engineering.SUBSTANCE: invention relates to laser equipment. Laser with Q-switching and mode synchronization contains an active medium, two end mirrors and one optical modulator used for both Q-switching and laser mode synchronization. One of the end mirrors of the resonator is composite, has a controlled reflection coefficient and is made in the form of a Michelson interferometer. Optical modulator is a phase modulator of the electrooptical type and is installed in one of the arms of the Michelson interferometer, the length of the second arm of which is tuned within the wavelength by means of a linear piezoelectric actuator.EFFECT: technical result of invention is faster operation and efficiency of nanosecond operating mode of laser.1 cl, 2 dwg

Description

Technical field

The invention relates to laser technology, in particular to devices for generating pulses of nanosecond and subnanosecond duration and can be used in systems for the pulsed processing of materials and laser location.

State of the art

In almost all known lasers of the nanosecond and subnanosecond ranges, the so-called a combined generation control circuit with active or passive mode locking in combination with active resonator Q-switching. Moreover, the implementation of such a circuit can be performed using modulators of various types installed in resonator circuits of various configurations.

In particular, in the patent RU 2240635 dated November 20, 2004, a picosecond Nd: YAG laser is described, for details see the article by the same authors (Gorbunkov M.V., Konyashkin A.V., Kostryukov P.V., Morozov V.B. . et al. “Picosecond fully solid-state Nd: YAG pulsed diode-pumped lasers and electro-optical generation control.” Quantum Electronics. 2005. V. 35. No. 1. P. 2-7), which uses thermally compensated low-voltage electro-optical modulators ( EOM) for active mode locking and resonator mode switching, as well as passive mode locking e using saturable semiconductor mirrors SESAM (Semiconductor Saturable Absorber Mirrors). The combined action of active-passive mode locking and negative feedback ensures the formation of ultrashort pulses and precise synchronization of the generation pulse with an external signal.

The disadvantage of this laser can be attributed to a rather complex optical resonator circuit with one passive modulator and three active EOM, as well as their synchronization and control scheme.

US Pat. No. 7,907,644 B2 dated March 15, 2011 proposes a picosecond laser circuit, the cavity of which contains an active medium with a wide luminescence band, a passive modulator based on a non-linear SESAM mirror for mode synchronization and obtaining the frequency sequence of ultrashort pulses, and a fast electro-optical modulator to provide at the right time time output single pulse from the resonator.

This system has large energy losses and low energy level of emitted pulses, which for most applications need to be further enhanced.

Finally, in patent RU 2478242 C2 of June 7, 2011 and a subsequent subsequent patent of the same authors RU 2606348 C1 of June 8, 2015, it is proposed to use a single traveling-wave acousto-optic modulator (AOM) for both mode synchronization and Q-switching, and install it in the center of curvature of the end mirror of the resonator. The second of the above patents is a technical development of the first and contains a large number of complicating elements and features that are not related to our invention. The first of these patents, RU 2478242 C2, by the totality of the features can be selected as a prototype of our device.

In the laser described in the patent prototype, a high level of peak power is achieved with stability and reproducibility of the output characteristics. The technical result is achieved due to the fact that in the laser, the cavity of which consists of two arms, in the first arm between the end mirror and the active element in the center of curvature of the end mirror is placed AOM, and in the second arm in front of the second end mirror a nonlinear optical lens with Kerr non-linearity and a rigid aperture in its focus.

To ensure active mode locking, the operating frequency of the AOM is set equal to (or a multiple) half of the intermode interval of the laser, and the switching frequency of the modulator (for example, in the range from one to hundreds of kilohertz) determines the pulse repetition rate of the modulated Q factor. Thus, it is possible to use one AOM both for Q-switching and for laser mode synchronization without the use of additional elements and mirrors. An additional crystal with Kerr nonlinearity placed in the second arm of the resonator can be used simultaneously to further reduce the pulse duration.

The disadvantages of this device include the limited performance of AOM, as well as high energy loss of radiation, firstly, due to diffraction losses characteristic of AOM, and, secondly, due to the particularity of the cavity Q factor control mode used by the authors of RU 2 478 242 C2 , in which the regime of modulation of the Q factor of the resonator is ensured by reducing losses in the zero diffraction order emerging from the resonator during inertial (due to the limitation of the speed of sound) disconnection of the fast operating frequency s AOM. These shortcomings are not fully resolved in the later dependent patent RU 2606348 C1.

The aim of this invention is to increase the speed and efficiency of the nanosecond laser mode, and, as in the prototype, the principle of using the same optical modulator in the cavity to synchronize modes and modulate the quality factor of the cavity, but this electro-optical type modulator performs active phase modulation with high speed and low energy loss. To implement the phase modulation mode, the electro-optical modulator is placed in one of the arms of the Michelson interferometer, which, in turn, is used as the output mirror of the resonator.

As a result, in a simpler and more efficient device, the output radiation parameters similar to the prototype were obtained, namely, trains of nanosecond pulses of microsecond duration, following with a repetition rate of up to several tens of kilohertz with an average power level of the order of several watts.

Disclosure of the invention

The present invention relates to laser technology, in particular, to devices for generating short-pulse laser radiation, the duration of which is controlled by a phase electro-optical modulator located in one of the arms of a Michelson interferometer used as an output mirror of a laser resonator with flat mirrors.

In FIG. 1 shows a simplified optical diagram of the proposed device.

In FIG. 2 shows a configuration of a device in a compact embodiment.

The circuit diagram of FIG. 1 includes the active medium of laser 1, three fully reflecting flat mirrors 2, 3, and 4, a beam splitter 5, and a phase electro-optical modulator (EOM) 6. Mirrors 2, 3 and a beam splitter 4 comprise a Michelson interferometer, 4 a rear blind mirror of the resonator. The arms of the interferometer are aligned with an accuracy of several hundred microns, which ensures the same reflectivity in the gain band of the signal of the active medium of the laser. The modulator consists of a pair of thermally compensated electro-optical crystals installed in a phase modulator configuration (M. Roth, M. Tseitlin, N. Angert. “Oxide Crystals for Electro-Optic Q-Switching of Lasers.” Glass Phys. Chem., 31, p. 86-95,2005).

The device operates as follows. An interferometer is used as a composite output mirror of a resonator with a controlled reflection coefficient. The initial maximum transmittance is adjusted by changing the length of one of the arms within the wavelength using a linear piezoelectric actuator on which the mirror 3 is mounted. A dynamic change in the reflection coefficient of the output mirror is carried out due to a change in the optical length of the EOM crystals when they are supplied with two electrical signals. The slow component of the signal in the form of a series of microsecond voltage pulses with an amplitude close to half-wave and a repetition rate from units to tens of kilohertz determines the modulation mode of the resonator Q factor. A fast high-frequency harmonic disturbance is applied to the same modulator at the frequency of double round-trip of the resonator with an amplitude not exceeding 10-20% of the half-wave voltage, which implements the active mode synchronization mode.

A key advantage of the proposed device with a phase modulator placed in a Michelson interferometer is the ability to optimize the energy efficiency of the radiation generation process by switching the output mirror of the resonator from a fully “open” state to a completely “closed” state and vice versa.

Important conditions for the stable operation of a resonator with a controlled interferometer are the high uniformity of diode pumping in the laser speaker and maintaining the thermal regime of the speaker at the same level. Otherwise, during the operation of the laser system, both the thermal lens resulting from inhomogeneous pumping and the pump radiation frequency can change, which will lead to unstable interference and instability of the laser output parameters.

The fulfillment of these conditions is achieved using a cooling device with high accuracy to maintain the temperature of the coolant (± 0.1 degrees). The interferometer itself is structurally rigid enough, and to compensate for the AC thermal lens, the pump current is fixed and one or more lenses mounted inside the resonator are selected (not shown in Fig. 1 and Fig. 2).

Note that with a technologically reasonable limitation of the frequency of the high-frequency electric signal of fast EOM control to 100 MHz, the optical length of the resonator is at least 150 cm. In this regard, it is advisable to use the optical circuit of the resonator “folded” four times in the device in question (see patent RU 2297084 dated April 10, 2007, claimed with the participation of one of the authors of the present invention). The scheme allows, through the use of one-dimensional retroreflectors (mirror "roofs"), to increase the resistance of the emitter to vibration and deformation perturbations and to make the device more compact.

An embodiment of the “folded” resonator in which the optical length of the resonator of 150 cm is packed in a laser emitter with a length not exceeding 35 cm is shown in FIG. 2. The active element 1 is located near the blind mirror of the resonator, the output mirror is made in the form of a controlled interferometer 7, the radiation is deployed by the mirrors of retroreflectors 8.

In our device in the compact cavity configuration shown in FIG. 2, a serial GN-50 quantron (Sino-Laser, China, see http://www.sino-laser.com) was installed based on Nd: YAG with continuous transverse diode pumping and EOM based on two RTP crystals (Rubidium Titanyl Phosphate , RbTiOPO 4 ) with dimensions 4 × 4 × 10 mm (Raicol Crystals, Israel, see http://www.raicol.com). The alignment of the resonator was reduced to the coaxial installation of the active medium 1 and the angular adjustment of the end mirrors 3 and 4 (see Fig. 1). Then, mirror 2 was adjusted to the maximum (or minimum, depending on the position of the piezoceramics) of the zero field of the interference pattern.

Two control modes were observed, each of which can find its own technological application. When applying only a slow control voltage (Q-switching), radiation was observed in the form of a kilohertz sequence of microsecond pulses. When both electrical control signals were supplied, the indicated output pulses were 100% modulated by a train of nanosecond synchronization pulses of the cavity modes. The average radiation power was about 2 watts.

Industrial applicability.

The proposed device intracavity control the duration of laser radiation using a controlled interferometer as an output mirror can be used to create lasers with nanosecond and subnanosecond duration for laser processing of materials and laser location.

Claims (1)

  1. A Q-switched laser with mode synchronization, the cavity of which contains an active medium, two end mirrors and one optical modulator used both for Q-switching and for laser mode synchronization, characterized in that one of the resonator end mirrors is composite, has a controlled coefficient reflection and made in the form of a Michelson interferometer, the optical modulator is a phase modulator of the electro-optical type and is installed in one of the arms of the Michelson interferometer, the length of the second The wave of which is adjusted within the wavelength using a linear piezoelectric actuator.
RU2018146379A 2018-12-24 2018-12-24 Laser emitter with controlled interferometer as output mirror RU2700343C1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
RU2018146379A RU2700343C1 (en) 2018-12-24 2018-12-24 Laser emitter with controlled interferometer as output mirror

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
RU2018146379A RU2700343C1 (en) 2018-12-24 2018-12-24 Laser emitter with controlled interferometer as output mirror

Publications (1)

Publication Number Publication Date
RU2700343C1 true RU2700343C1 (en) 2019-09-16

Family

ID=67989758

Family Applications (1)

Application Number Title Priority Date Filing Date
RU2018146379A RU2700343C1 (en) 2018-12-24 2018-12-24 Laser emitter with controlled interferometer as output mirror

Country Status (1)

Country Link
RU (1) RU2700343C1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4302730A (en) * 1979-06-04 1981-11-24 The United States Of America As Represented By The Secretary Of The Navy Cavity dumper
US5163059A (en) * 1991-05-09 1992-11-10 Coherent, Inc. Mode-locked laser using non-linear self-focusing element
RU2478242C2 (en) * 2011-06-07 2013-03-27 Учреждение Российской академии наук Институт автоматики и электрометрии Сибирского отделения РАН Q-switched and mode-coupled laser
RU128020U1 (en) * 2012-10-09 2013-05-10 Российская Федерация, от имени которой выступает Государственная корпорация по атомной энергии "Росатом" - Госкорпорация "Росатом" Optical system for producing powerful laser radiation modulated in the high frequency range
EP2424051B1 (en) * 2010-08-25 2015-08-12 Uniklasers Ltd. Intra-cavity second harmonic generation (SHG) laser device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4302730A (en) * 1979-06-04 1981-11-24 The United States Of America As Represented By The Secretary Of The Navy Cavity dumper
US5163059A (en) * 1991-05-09 1992-11-10 Coherent, Inc. Mode-locked laser using non-linear self-focusing element
EP2424051B1 (en) * 2010-08-25 2015-08-12 Uniklasers Ltd. Intra-cavity second harmonic generation (SHG) laser device
RU2478242C2 (en) * 2011-06-07 2013-03-27 Учреждение Российской академии наук Институт автоматики и электрометрии Сибирского отделения РАН Q-switched and mode-coupled laser
RU128020U1 (en) * 2012-10-09 2013-05-10 Российская Федерация, от имени которой выступает Государственная корпорация по атомной энергии "Росатом" - Госкорпорация "Росатом" Optical system for producing powerful laser radiation modulated in the high frequency range

Similar Documents

Publication Publication Date Title
Yoshida et al. High-power and high-contrast optical parametric chirped pulse amplification in β-BaB 2 O 4 crystal
CA2182368C (en) Passively q-switched picosecond microlaser
Haus et al. Analytic theory of additive pulse and Kerr lens mode locking
US5943351A (en) Intra-cavity and inter-cavity harmonics generation in high-power lasers
US7630418B2 (en) Laser system for generation of high-power sub-nanosecond pulses with controllable wavelength in 2-15 μm region
JP5232782B2 (en) Method of controlling light source having precisely controlled wavelength conversion average output, and wavelength conversion system
Bauer et al. Mode-locked Yb: YAG thin-disk oscillator with 41 µJ pulse energy at 145 W average infrared power and high power frequency conversion
US4174504A (en) Apparatus and method for cavity dumping a Q-switched laser
Bouma et al. Hybrid mode locking of a flash-lamp-pumped Ti: Al 2 O 3 laser
Keller et al. Coupled-cavity resonant passive mode-locked Ti: sapphire laser
US5212698A (en) Dispersion compensation for ultrashort pulse generation in tuneable lasers
Kafka et al. Prism-pair dispersive delay lines in optical pulse compression
US7180918B2 (en) Self-seeded single-frequency solid-state ring laser and system using same
JP4323917B2 (en) Method for reducing relative timing drift
Spence et al. Regeneratively initiated self-mode-locked Ti: sapphire laser
Goodberlet et al. Self-starting additive-pulse mode-locked diode-pumped Nd: YAG laser
US5689363A (en) Long-pulse-width narrow-bandwidth solid state laser
Ryan et al. Comparison of synchronous pumping and passive mode-locking of cw dye lasers for the generation of picosecond and subpicosecond light pulses
Keller et al. Ultrafast solid-state lasers
Malcolm et al. Additive-pulse mode locking of a diode-pumped Nd: YLF laser
JP2002536823A (en) High repetition rate passively mode-locked solid-state laser
JP2597845B2 (en) High repetition pulsed laser apparatus
EP0109411B1 (en) Synchronously-pumped phase-conjugate laser
Chandra et al. Prism‐dye laser
Zayhowski et al. Diode-pumped microchip lasers electro-optically Q switched at high pulse repetition rates