bjt amplifier experiment

• Network Sites:
• Technical Articles
• Market Insights

• Or sign in with
• iHeartRadio

• Si Lab - BJT Common-emitter Amplifier

Join our Engineering Community! Sign-in with:

• DIY Electronics Projects

Discrete Semiconductor Circuit Projects

• Si Lab - Intro to Discrete Semiconductor Circuits
• Si Lab - Commutating Diode
• Si Lab - Half-wave Rectifier
• Si Lab - Full-wave Bridge Rectifier
• Si Lab - Full-wave Center-tap Rectifier
• Si Lab - Full-wave Bridge Rectifier With Output Filtering
• Si Lab - Zener Diode Voltage Regulator
• Si Lab - Bipolar Transistor as a Switch
• Si Lab - JFET Switching Circuit and Static Electricity Sensor
• Si Lab - Light Sensor (LED Photodetector)
• Si Lab - BJT Common-collector Voltage Follower
• Si Lab - Multi-stage Amplifier
• Si Lab - A Simple BJT Current Mirror Circuit
• Si Lab - JFET Current Regulator
• Si Lab - Differential Amplifier
• Si Lab - Simple Op Amp
• Si Lab - Astable Multivibrator Audio Oscillator
• Tube Lab - Vacuum Tube Audio Amplifier

In this hands-on semiconductor electronics experiment, construct a common-emitter amplifier using a bipolar junction transistor (BJT) and learn about amplifier gain and feedback.

Project overview.

The common-emitter amplifier circuit illustrated in Figure 1 is one of the most important analog transistor circuits. 

Figure 1. Schematic diagram of a BJT common-emitter amplifier circuit with potentiometer input control.

In this project, learn how to calculate amplifier voltage gain , be introduced to the difference between an inverting and a noninverting amplifier, and evaluate two different methods for adding  negative feedback to this amplifier circuit.

Parts and Materials

• One NPN transistor—model 2N2222 or 2N3403 recommended
• Two 6 V batteries
• One 10 kΩ potentiometer , single-turn, linear taper
• One 1 MΩ resistor
• One 100 kΩ resistor
• One 10 kΩ resistor
• One 1.5 kΩ resistor

Learning Objectives

• Design of a simple common-emitter amplifier circuit
• How to measure the amplifier's voltage gain
• The difference between an inverting and a noninverting amplifier
• Ways to introduce negative feedback in an amplifier circuit

Instructions

Step 1:  Build the common-emitter amplifier circuit shown in the schematic of Figure 1 and illustrated in Figure 2.

Figure 2. Breadboard implementation of a BJT common-emitter amplifier circuit with potentiometer input control.

Step 2: Measure the output voltage (voltage measured between the transistor’s collector terminal and ground ) and the input voltage (voltage measured between the potentiometer’s wiper terminal and ground) for several position settings of the potentiometer. I recommend determining the output voltage range as the potentiometer is adjusted through its entire range of motion, then choosing several voltages spanning that output range to take measurements at.

For example, if full rotation on the potentiometer drives the amplifier circuit’s output voltage from 0.1 V (low) to 11.7 V (high), choose several voltage levels between those limits (1, 3, 5, 7, 9, and 11 V). Measuring the output voltage with a meter, adjust the potentiometer to obtain each of these predetermined voltages at the output, noting the exact figure for later reference.

Then, measure the exact input voltage producing that output voltage, and record that voltage figure as well. In the end, you should have a table of numbers representing several different output voltages along with their corresponding input voltages.

Step 3:  Calculate the voltage gain using any two pairs of input and output voltages—divide the difference in output voltages by the difference in input voltages:

$$Gain = \frac{\Delta V_{OUT}}{\Delta V_{IN}} = \frac{V_{OUT2} - V_{OUT1}}{V_{IN2} - V_{IN1}}$$

For example, if an input voltage of 1.5 V gives me an output voltage of 7.0 V and an input voltage of 1.66 V gives me an output voltage of 1.0 V, the amplifier’s voltage gain is:

$$Gain = \frac{V_{OUT2} - V_{OUT1}}{V_{IN2} - V_{IN1}} = \frac{7.0 - 1.0}{1.5-1.66} = -37.5$$

You should immediately notice two characteristics while taking these voltage measurements:

• The input-to-output effect is reversed. That is, an increasing input voltage results in a decreasing output voltage. This effect is known as signal inversion, and this kind of amplifier is an inverting amplifier.
• This amplifier exhibits a strong voltage gain. A small change in input voltage results in a large change in output voltage. This should stand in stark contrast to the voltage follower amplifier circuit discussed earlier, which had a voltage gain of about 1.

Common-emitter amplifiers are widely used due to their high voltage gain, but they are rarely used in as crude a form as this. Although this amplifier circuit works to demonstrate the basic concept, it is very susceptible to changes in temperature.

Step 4:  Try leaving the potentiometer in one position and heating the transistor by grasping it firmly with your hand or heating it with some other source of heat, such as an electric hair dryer.  WARNING : be careful not to get it so hot that your plastic breadboard melts!

Step 5:  You may also explore temperature effects by cooling the transistor. Touch an ice cube to its surface and note the change in output voltage. When the transistor’s temperature changes, its base-emitter diode characteristics change, resulting in different amounts of base current for the same input voltage. This, in turn, alters the controlled current through the collector terminal, thus affecting output voltage.

Using Feedback in Amplifier Circuits

Changes caused by temperature may be minimized through the use of signal feedback , whereby a portion of the output voltage is fed back to the amplifier’s input so as to have a negative, or canceling, effect on voltage gain. The temperature stability is improved at the expense of voltage gain; a compromise solution, but practical nonetheless.

Step 6:  Perhaps the simplest way to add negative feedback to a common-emitter amplifier is to add some resistance between the emitter terminal and ground so that the input voltage becomes divided between the base-emitter PN junction and the voltage drop across the new resistance. Add the 1.5 kΩ resistor between the emitter and ground to the circuit, as illustrated in Figures 3 and 4.

Figure 3. Schematic diagram of a BJT common-emitter amplifier with added resistance at the emitter node.

Figure 4. Breadboard implementation of a BJT common-emitter amplifier with added resistance at the emitter node.

Step 7:  Repeat the same voltage measurement and recording exercise with the 1.5 kΩ resistor installed. 

Step 8:  Calculate the new (reduced) voltage gain of this circuit.

Step 9:  Try altering the transistor’s temperature again and noting the output voltage for a steady input voltage. Does it change more or less than without the 1.5 kΩ resistor?

Step 10:  Another method of introducing negative feedback to this amplifier circuit is to couple the output to the input through a high-value resistor. Connect a 1 MΩ resistor between the transistor’s collector and base terminals, as illustrated in Figures 5 and 6.

Figure 5. Schematic diagram of a BJT common-emitter amplifier with collector-base resistive feedback.

Figure 6.  Breadboard implementation of a BJT common-emitter amplifier with collector-base resistive feedback.

Step 11: Calculate the voltage gain of this new circuit and evaluate the temperature response. Although this different method of feedback accomplishes the same goal of increased stability by diminishing gain, the two feedback circuits will not behave identically.

Step 12:  Measure the range of possible output voltages with each feedback scheme (the low and high voltage values obtained with a full sweep of the input voltage potentiometer) and how this differs between the two circuits.

SPICE Simulation of a BJT Common-emitter Amplifier

To simulate the BJT voltage follower circuit, we can use the circuit shown in Figure 7 and the associated SPICE simulation netlist and input deck that follows.

Figure 7.  BJT common-emitter amplifier schematic for SPICE simulation.

Netlist (make a text file containing the following text, verbatim):

This SPICE simulation sets up a circuit with a variable DC voltage source ( vin ) as the input signal and measures the corresponding output voltage between nodes 2 and 0. The input voltage is varied, or swept, from 0 to 2 V in 0.05 V increments.

The results are shown on a plot, with the input voltage appearing as a straight, increasing line. Due to the high gain of the amplifier, the output voltage will be a step function—beginning high and ending low, with a steep change in the middle where the transistor is in its active mode of operation.

Related Content

Learn more about the fundamentals behind this project in the resources below.

• Bipolar Junction Transistors
• Common-emitter Amplifier

Worksheets:

• Bipolar Transistor Biasing Circuits Worksheet
• Class A BJT Amplifiers Worksheet
• Bipolar Junction Transistor (BJT) Theory Worksheet
• Textbook Index

Lessons in Electric Circuits

Volumes ».

• Direct Current (DC)
• Alternating Current (AC)
• Semiconductors
• Digital Circuits
• EE Reference

Chapters »

• 1 Introduction to Electronics Projects
• 2 Basic Projects and Test Equipment
• 3 DC Circuit Projects
• 4 AC Circuit Projects

Pages »

• 6 Analog IC Projects
• 7 Digital IC Projects
• 8 555 Timer Circuit Projects
• 9 Contributor List
• Advanced Textbooks Practical Guide to Radio-Frequency Analysis and Design
• Silicon Labs Bluetooth Solutions
• Driving Piezoelectric Actuators with Linear Amplifiers
• Smart Bench Essentials and Remote Lab Access
• Introduction to the CFA: Current-Feedback Amplifiers vs. Voltage-Feedback Amplifiers
• Silicon Labs Wi-SUN | Tech Chats - Silicon Labs and Mouser Electronics
• Renesas Lab on the Cloud: Evaluate Boards Remotely through an Intuitive GUI

You May Also Like

Future Picks Presents: Vishay microBUCK® Product Family

In Partnership with Future Electronics

Bluetooth Mesh Feature Enhancements

by Silicon Labs

Intel Makes Way for the AI PC Era With New Lunar Lake Architecture

by Jake Hertz

System Solution Guide: Heat Pumps

Getting To Know the Gerber File Format and File Names

by Carmen Zheng, NextPCB

Welcome Back

Don't have an AAC account? Create one now .

Forgot your password? Click here .

• Home  / 
• Electronics  / 
• Circuit Design  / 

BJT Common Emitter Amplifier

The BJT common emitter amplifier is a general-purpose BJT-based amplifier that it typically used for voltage amplification. It offers great voltage gain and ok current gain . The input impedance is moderate but unfortunately it has high output impedance . The output is inverted with respect to the input. It is commonly followed with a buffer circuit such as a common-collector amplifier to reduce the output impedance. The common emitter amplifier find use in audio and RF applications.

The MOSFET analogue to the BJT common emitter amplifier is the common source amplifier .

Properties:

Lower case letters used below represent changes in quantities, e.g. \(V_C\) is the voltage at the collector, whilst \(v_c\) is the change in voltage at the collector, \(\Delta V_C\).

How A Common Emitter Amplifier Works

Schematic for a common emitter amplifier with DC bias and AC coupling.

• \(R1\) and \(R2\) are used to provide a DC bias point for the base of the transistor, using the standard resistor divider technique (to be exact, you also have to take into account that the transistor draws some current from the output of the resistor divider, but generally you can ignore that).
• \(C1\) is used to AC couple the input signal to the DC bias point – it’s value is chosen so that it appears as a short for the AC signal frequencies of interest but blocks DC.
• \(R_E\) adds emitter degeneration 1 and makes the amplifier gain more stable with variations in \(\beta\). \(C_E\) is the emitter bypass capacitor and is used to bypass \(R_E\) so that the AC signal essentially sees the emitter connected directly to ground.
• \(R_C\) is the collector resistor which helps set the voltage gain of the amplifier. Sometimes this is called the load resistor 2 , however this can be confusing, as typically the “load” is placed after the output AC coupling capacitor.
• \(R_L\) is the load resistance. You may see this and \(C_{OUT}\) omitted from some diagrams of the common emitter amplifier.
• \(C_{OUT}\) is the AC coupling capacitor on the output, which blocks the DC component, similarly to \(C_{IN}\).

Gain Of A Common Emitter Amplifier

Diagram showing how the gain equation for a common emitter amplifier is found.

The voltage gain of a common-emitter amplifier (by definition) is:

Remember that \(v_{in}\) and \(v_{out}\) are lower case and represent changes in the signal (i.e. deltas, and ignore their DC levels). Now, assuming \(i_c \approx i_e\), the change in voltage at the output is:

And the change in voltage at the input is:

Note that we have to take the internal emitter resistance \(r_e\) into account here, as the emitter bypass capacitor is going to remove the \(R_E\) term further down, leaving only \(r_e\).

Substituting these equations for \(v_{in}\) and \(v_{out}\) into the gain equation gives:

Remember that the value for \(r_e\) is dependent on the emitter current at the DC bias point:

Thus, for our signal frequencies at which the \(C_E\) capacitor shorts out external resistor \(R_E\), the emitter resistance is just \(r_e\) and the gain becomes:

The voltage gain of the common emitter amplifier is not dependent on the current gain \(\beta\) of the BJT . This is good news, as this property cannot be tightly controlled during manufacture and usually varies between “identical” transistors by a few \(100%\) or more!

Common Emitter Amplifier Design Process

How do you design a common emitter amplifier? Let’s do a worked example to progress through the design steps.

Assumptions

• \(V_{CC}\) is \(12V\)
• We’ll be using the venerable BC548BTA NPN transistor from onsemi in our amplifier.
• We’re trying to get as much gain as possible (a noble quest).

Choose collector current: Chose a suitable DC collector current for your amplifier. A reasonable choice would be \(I_C = 10mA\) (max. \(I_C\) for the BC547B is \(100mA\)).

Determine the emitter resistor \(R_E\): As a rule of thumb, 10% of \(V_{CC}\) is normally dropped across \(R_E\) 3 4 :

Find the collector resistor \(R_C\): We are dropping \(1.2V\) across the emitter resistor. That leaves \(10.8V\) to be dropped across the collector resistor and the BJT. Assuming a saturation voltage of 200mV, this gives the BJT \(10.6V\) of swing. For maximum symmetrical output, we want to drop half of this \(10.6V\) across the collector resistor:

Find the base current: Calculate \(I_B\) using the approximate gain:

Determine the base voltage \(V_B\): \(V_B\) is just the emitter voltage plus the diode \(V_BE\) drop:

Calculate resistor divider values : Chose \(R1\) and \(R2\) to set the output of the resistor divider to match this base voltage. We also want to make sure the current flowing through the resistor is 10x the current that will be sucked out of it into the base of the transistor, that way we can ignore the loading of the BJT when calculating the resistor values.

Now we can easily calculate the value of \(R2\):

And \(R1\):

Calculate input AC coupling capacitor: The rule of thumb is to make sure the impedance of the capacitor is 10x less that the AC impedance of the resistor divider at the lowest frequency of interest 5 . Our lowest frequency of interest is \(20Hz\).

Calculate emitter bypass capacitor: The same rule of thumb applies to \(C_E\), except this time it’s impedance should be 10x smaller than \(R_E\):

Calculate the gain :

The finished schematic, along with voltage sources ready for simulation is shown below.

The finished schematic of our common emitter amplifier, ready for simulation.

Given the large gain of \(46.5dB\), I didn’t want to saturate the output so I chose an input sine wave signal with an amplitude of \(10mV\) at a frequency of \(1kHz\). The simulated input and output voltages are shown below ( note the change in the y-axis scale - the input is in \(mV\) and the output is in \(V\) ).

Simulation results showing \(V_{OUT}\) vs. \(V_{IN}\).

You can clearly see the \(180^{\circ}\) phase shift between the input and output in the plots above. Also, the output decoupling capacitor is doing a good job at removing the DC component and centers around signal around \(0V\).

The simulated frequency response shown below is close to what we expect. The simulated gain of around \(42dB\) is close enough to our calculated gain of \(46.5dB\) considering all the approximations we made! The phase shift is \(180^{\circ}\) for most of our signal bandwidth.

The simulated frequency response of our common emitter amplifier.

The gain of the circuit would drop significantly if the load resistance was decreased, due to the medium amount of output impedance (ideally this would be \(0\Omega\)). When designing a common emitter amplifier, make sure you are not loading it too much. You can decrease the output impedance of a common emitter amplifier by increase the amount of collector quiescent current \(I_C\).

Analog Devices (2020, Mar 23). Activity: Common Emitter Amplifier . Retrieved 2022-08-20, from https://wiki.analog.com/university/courses/electronics/electronics-lab-5 .  ↩︎

Bob Harper (2018, Dec). Common Emitter Transistor Amplifier . Diyode. Retrieved 2022-08-21 from https://diyodemag.com/education/common_emitter_transistor_amplifier .  ↩︎

Stack Exchange: Electrical Engineering (2021, Oct 13). How to choose resistors’ value for common emitter amplifier? . Retrieved 2022-08-17, from https://electronics.stackexchange.com/questions/127491/how-to-choose-resistors-value-for-common-emitter-amplifier .  ↩︎

Electronics Notes. Transistor Common Emitter Circuit Design . Retrieved 2022-08-20, from https://www.electronics-notes.com/articles/analogue_circuits/transistor/transistor-common-emitter-amplifier-circuit-design.php .  ↩︎

Electronics Tutorials. Common Emitter Amplifier . Retrieved 2022-08-18, from https://www.electronics-tutorials.ws/amplifier/amp_2.html .  ↩︎

Geoffrey Hunter

Dude making stuff.

Related Content

• Shift Registers
• Peltiers (Thermoelectric Cooler)
• Electropermanent Magnets (EPMs)
• Neon Sign Transformers
• electronics
• transistors
• bipolar junction transistors
• common emitter amplifier

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

• View all journals
• Explore content
• About the journal
• Publish with us
• Sign up for alerts
• Published: 26 June 2024

Titanium:sapphire-on-insulator integrated lasers and amplifiers

• Joshua Yang 1   na1 ,
• Kasper Van Gasse 1 , 2   na1 ,
• Daniil M. Lukin 1   na1 ,
• Melissa A. Guidry 1 ,
• Geun Ho Ahn 1 ,
• Alexander D. White   ORCID: orcid.org/0000-0002-5387-310X 1 &
• Jelena Vučković   ORCID: orcid.org/0000-0002-4603-9686 1  

Nature volume  630 ,  pages 853–859 ( 2024 ) Cite this article

3448 Accesses

130 Altmetric

Metrics details

• Integrated optics
• Microresonators
• Quantum optics
• Solid-state lasers

Titanium:sapphire (Ti:sapphire) lasers have been essential for advancing fundamental research and technological applications, including the development of the optical frequency comb 1 , two-photon microscopy 2 and experimental quantum optics 3 , 4 . Ti:sapphire lasers are unmatched in bandwidth and tuning range, yet their use is restricted because of their large size, cost and need for high optical pump powers 5 . Here we demonstrate a monocrystalline titanium:sapphire-on-insulator (Ti:SaOI) photonics platform that enables dramatic miniaturization, cost reduction and scalability of Ti:sapphire technology. First, through the fabrication of low-loss whispering-gallery-mode resonators, we realize a Ti:sapphire laser operating with an ultralow, sub-milliwatt lasing threshold. Then, through orders-of-magnitude improvement in mode confinement in Ti:SaOI waveguides, we realize an integrated solid-state (that is, non-semiconductor) optical amplifier operating below 1 μm. We demonstrate unprecedented distortion-free amplification of picosecond pulses to peak powers reaching 1.0 kW. Finally, we demonstrate a tunable integrated Ti:sapphire laser, which can be pumped with low-cost, miniature, off-the-shelf green laser diodes. This opens the doors to new modalities of Ti:sapphire lasers, such as massively scalable Ti:sapphire laser-array systems for several applications. As a proof-of-concept demonstration, we use a Ti:SaOI laser array as the sole optical control for a cavity quantum electrodynamics experiment with artificial atoms in silicon carbide 6 . This work is a key step towards the democratization of Ti:sapphire technology through a three-orders-of-magnitude reduction in cost and footprint and introduces solid-state broadband amplification of sub-micron wavelength light.

This is a preview of subscription content, access via your institution

Access options

Access Nature and 54 other Nature Portfolio journals

Get Nature+, our best-value online-access subscription

24,99 € / 30 days

cancel any time

Subscribe to this journal

Receive 51 print issues and online access

185,98 € per year

only 3,65 € per issue

Buy this article

• Purchase on Springer Link
• Instant access to full article PDF

Prices may be subject to local taxes which are calculated during checkout

Similar content being viewed by others

Photonic-circuit-integrated titanium:sapphire laser

High output mode-locked laser empowered by defect regulation in 2D Bi2O2Se saturable absorber

Ultrafast tunable lasers using lithium niobate integrated photonics

Data availability.

The data used to support the findings in this work are presented in the main text and Supplementary Information .

Holzwarth, R. et al. Optical frequency synthesizer for precision spectroscopy. Phys. Rev. Lett. 85 , 2264–2267 (2000).

Article   ADS   CAS   PubMed   Google Scholar  

Helmchen, F. & Denk, W. Deep tissue two-photon microscopy. Nat. Methods 2 , 932–940 (2005).

Article   CAS   PubMed   Google Scholar  

Semeghini, G. et al. Probing topological spin liquids on a programmable quantum simulator. Science 374 , 1242–1247 (2021).

Ebadi, S. et al. Quantum phases of matter on a 256-atom programmable quantum simulator. Nature 595 , 227–232 (2021).

Moulton, P. F. Spectroscopic and laser characteristics of Ti:Al 2 O 3 . J. Opt. Soc. Am. B 3 , 125–133 (1986).

Article   ADS   CAS   Google Scholar  

Lukin, D. M. et al. Two-emitter multimode cavity quantum electrodynamics in thin-film silicon carbide photonics. Phys. Rev. X 13 , 011005 (2023).

CAS   Google Scholar  

Moulton, P. Ti-doped sapphire: tunable solid-state laser. Opt. News 8 , 9 (1982).

Article   Google Scholar  

Morgner, U. et al. Sub-two-cycle pulses from a Kerr-lens mode-locked Ti:sapphire laser. Opt. Lett. 24 , 411–413 (1999).

Prakash, R. et al. Two-photon optogenetic toolbox for fast inhibition, excitation and bistable modulation. Nat. Methods 9 , 1171–1179 (2012).

Article   CAS   PubMed   PubMed Central   Google Scholar  

Xu, C. & Webb, W. W. Measurement of two-photon excitation cross sections of molecular fluorophores with data from 690 to 1050 nm. J. Opt. Soc. Am. B 13 , 481–491 (1996).

Leedle, K. J., Pease, R. F., Byer, R. L. & Harris, J. S. Laser acceleration and deflection of 96.3 keV electrons with a silicon dielectric structure. Optica 2 , 158–161 (2015).

Kfir, O. et al. Controlling free electrons with optical whispering-gallery modes. Nature 582 , 46–49 (2020).

Santori, C., Fattal, D., Vučković, J., Solomon, G. S. & Yamamoto, Y. Indistinguishable photons from a single-photon device. Nature 419 , 594–597 (2002).

Rugar, A. E. et al. Quantum photonic interface for tin-vacancy centers in diamond. Phys. Rev. X 11 , 031021 (2021).

Rizzo, A. et al. Massively scalable Kerr comb-driven silicon photonic link. Nat. Photon. 17 , 781–790 (2023).

Boes, A. et al. Lithium niobate photonics: unlocking the electromagnetic spectrum. Science 379 , eabj4396 (2023).

Riemensberger, J. et al. A photonic integrated continuous-travelling-wave parametric amplifier. Nature 612 , 56–61 (2022).

Xiang, C. et al. Laser soliton microcombs heterogeneously integrated on silicon. Science 373 , 99–103 (2021).

Xiang, C. et al. 3D integration enables ultralow-noise isolator-free lasers in silicon photonics. Nature 620 , 78–85 (2023).

Article   ADS   CAS   PubMed   PubMed Central   Google Scholar  

Zhou, Z. et al. Prospects and applications of on-chip lasers. eLight 3 , 1–25 (2023).

Article   PubMed   PubMed Central   Google Scholar  

Tran, M. A. et al. Extending the spectrum of fully integrated photonics to submicrometre wavelengths. Nature 610 , 54–60 (2022).

Corato-Zanarella, M. et al. Widely tunable and narrow-linewidth chip-scale lasers from near-ultraviolet to near-infrared wavelengths. Nat. Photon. 17 , 157–164 (2023).

Zhang, Z. et al. Photonic integration platform for rubidium sensors and beyond. Optica 10 , 752–753 (2023).

Article   CAS   Google Scholar  

Ahmad, F. R., Tseng, Y. W., Kats, M. A. & Rana, F. Energy limits imposed by two-photon absorption for pulse amplification in high-power semiconductor optical amplifiers. Opt. Lett. 33 , 1041–1043 (2008).

Chang, L., Liu, S. & Bowers, J. E. Integrated optical frequency comb technologies. Nat. Photon. 16 , 95–108 (2022).

Liu, Y. et al. A photonic integrated circuit–based erbium-doped amplifier. Science 376 , 1309–1313 (2022).

Liu, Y. et al. A fully hybrid integrated erbium-based laser. Preprint at https://arxiv.org/abs/2305.03652 (2023).

Grivas, C., Shepherd, D. P., May-Smith, T. C., Eason, R. W. & Pollnau, M. Single-transverse-mode Ti:sapphire rib waveguide laser. Opt. Express 13 , 210–215 (2005).

Grivas, C. et al. Generation of multi-gigahertz trains of phase-coherent femtosecond laser pulses in Ti:sapphire waveguides. Laser Photon. Rev. 12 , 1800167 (2018).

Article   ADS   Google Scholar  

Grivas, C., Corbari, C., Brambilla, G. & Lagoudakis, P. G. Tunable, continuous-wave Ti:sapphire channel waveguide lasers written by femtosecond and picosecond laser pulses. Opt. Lett. 37 , 4630–4632 (2012).

Yang, T.-T. et al. Widely tunable, 25-mW power, Ti:sapphire crystal-fiber laser. IEEE Photon. Technol. Lett. 31 , 1921–1924 (2019).

Wang, S.-C. et al. Laser-diode pumped glass-clad Ti:sapphire crystal fiber laser. Opt. Lett. 41 , 3217–3220 (2016).

Azeem, F. et al. Ultra-low threshold titanium-doped sapphire whispering-gallery laser. Adv. Opt. Mater. 10 , 2102137 (2022).

Wang, Y., Holguín-Lerma, J. A., Vezzoli, M., Guo, Y. & Tang, H. X. Photonic-circuit-integrated titanium:sapphire laser. Nat. Photon. 17 , 338–345 (2023).

Guo, Y. et al. Hybrid integrated external cavity laser with a 172-nm tuning range. APL Photon. 7 , 066101 (2022).

Guo, J. et al. E-band widely tunable, narrow linewidth heterogeneous laser on silicon. APL Photon. 8 , 046114 (2023).

Lukin, D. M. et al. 4H-silicon-carbide-on-insulator for integrated quantum and nonlinear photonics. Nat. Photon. 14 , 330–334 (2020).

Bouma, B. E. et al. Optical coherence tomography. Nat. Rev. Methods Primers 2 , 79 (2022).

Drexler, W. et al. In vivo ultrahigh-resolution optical coherence tomography. Opt. Lett. 24 , 1221–1223 (1999).

Ideguchi, T. et al. Coherent Raman spectro-imaging with laser frequency combs. Nature 502 , 355–358 (2013).

Major, A., Yoshino, F., Nikolakakos, I., Aitchison, J. S. & Smith, P. W. E. Dispersion of the nonlinear refractive index in sapphire. Opt. Lett. 29 , 602–604 (2004).

Article   ADS   PubMed   Google Scholar  

Shtyrkova, K. et al. Integrated CMOS-compatible Q-switched mode-locked lasers at 1900nm with an on-chip artificial saturable absorber. Opt. Express 27 , 3542–3556 (2019).

Byun, H. et al. Integrated low-jitter 400-MHz femtosecond waveguide laser. IEEE Photon. Technol. Lett. 21 , 763–765 (2009).

Franken, C. A. A. et al. Hybrid-integrated diode laser in the visible spectral range. Opt. Lett. 46 , 4904–4907 (2021).

Awschalom, D. D., Hanson, R., Wrachtrup, J. & Zhou, B. B. Quantum technologies with optically interfaced solid-state spins. Nat. Photon. 12 , 516–527 (2018).

Aslam, N. et al. Quantum sensors for biomedical applications. Nat. Rev. Phys. 5 , 157–169 (2023).

Bhaskar, M. K. et al. Experimental demonstration of memory-enhanced quantum communication. Nature 580 , 60–64 (2020).

Davis, E. J. et al. Probing many-body dynamics in a two-dimensional dipolar spin ensemble. Nat. Phys. 19 , 836–844 (2023).

Evans, R. E. et al. Photon-mediated interactions between quantum emitters in a diamond nanocavity. Science 362 , 662–665 (2018).

Lukin, D. M. et al. Multiemitter cavity quantum electrodynamics in 4H-silicon carbide-on-insulator photonics. In CLEO 2023 Fundamental Science , Technical Digest Series FTu3C.4 (Optica Publishing Group, 2023).

Catanzaro, D., Lukin, D. M., Lustig, E., Guidry, M. A. & Vučković, J. Cryogenic fiber-coupled waveguide probe co-integrated with electrical control lines. In CLEO 2023 Science and Innovations , Technical Digest Series JTu2A.47 (Optica Publishing Group, 2023).

Nagy, R. et al. Quantum properties of dichroic silicon vacancies in silicon carbide. Phys. Rev. Appl. 9 , 034022 (2018).

Levonian, D. et al. Optical entanglement of distinguishable quantum emitters. Phys. Rev. Lett. 128 , 213602 (2022).

Newman, Z. L. et al. Architecture for the photonic integration of an optical atomic clock. Optica 6 , 680–685 (2019).

Spencer, D. T. et al. An optical-frequency synthesizer using integrated photonics. Nature 557 , 81–85 (2018).

He, C. et al. Ultra-high Q alumina optical microresonators in the UV and blue bands. Opt. Express 31 , 33923–33929 (2023).

Li, M. et al. Integrated pockels laser. Nat. Commun. 13 , 5344 (2022).

Zhao, H. et al. Visible-to-near-infrared octave spanning supercontinuum generation in a silicon nitride waveguide. Opt. Lett. 40 , 2177–2180 (2015).

Ledezma, L. et al. Intense optical parametric amplification in dispersion-engineered nanophotonic lithium niobate waveguides. Optica 9 , 303–308 (2022).

Burton, H., Debardelaben, C., Amir, W. & Planchon, T. A. Temperature dependence of Ti:sapphire fluorescence spectra for the design of cryogenic cooled Ti:sapphire CPA laser. Opt. Express 25 , 6954–6962 (2017).

Soykal, Ö. O., Dev, P. & Economou, S. E. Silicon vacancy center in 4 H -SiC: Electronic structure and spin-photon interfaces. Phys. Rev. B 93 , 081207(R) (2016).

Chen, T., Lee, H., Li, J. & Vahala, K. J. A general design algorithm for low optical loss adiabatic connections in waveguides. Opt. Express 20 , 22819–22829 (2012).

van Rees, A. et al. Long-term absolute frequency stabilization of a hybrid-integrated InP-Si 3 N 4 diode laser. IEEE Photon. J. 15 , 1502408 (2023).

Google Scholar  

Download references

Acknowledgements

We thank C. Langrock for his help with lapping and polishing, K. Yang for the discussions and guidance on fibre tapering, L. Mandyam for technical support in device fabrication and M. M. Fejer for access to laboratory equipment. We acknowledge funding support from the IET A. F. Harvey Prize, the Vannevar Bush Faculty Fellowship from the US Department of Defense, DARPA LUMOS and the AFOSR under award no. FA9550-23-1-0248. J.Y. acknowledges support from the National Defense Science and Engineering Graduate (NDSEG) Fellowship. K.V.G. acknowledges support from the Research Foundation—Flanders (12ZB520N). Part of this work was performed at the Stanford Nano Shared Facilities (SNSF)/Stanford Nanofabrication Facility (SNF), supported by the National Science Foundation under award no. ECCS-2026822.

Author information

These authors contributed equally: Joshua Yang, Kasper Van Gasse, Daniil M. Lukin

Authors and Affiliations

E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA

Joshua Yang, Kasper Van Gasse, Daniil M. Lukin, Melissa A. Guidry, Geun Ho Ahn, Alexander D. White & Jelena Vučković

Photonics Research Group, Ghent University-imec, Ghent, Belgium

Kasper Van Gasse

You can also search for this author in PubMed   Google Scholar

Contributions

J.Y. and K.V.G. designed the devices. J.Y., K.V.G., D.M.L. and G.H.A. fabricated the devices. J.Y., K.V.G., D.M.L., M.A.G. and A.D.W. ran the device simulations. J.Y., K.V.G., D.M.L., M.A.G. and A.D.W. assisted with the experimental setup. J.Y., K.V.G., D.M.L. and M.A.G. conducted the measurements on the microdisk lasers. J.Y., K.V.G., D.M.L. and M.A.G. conducted the measurements on the waveguide amplifiers. J.Y., K.V.G. and D.M.L. conducted the measurements on the waveguide lasers. J.Y. and D.M.L. conducted the cavity QED experiment. J.Y., K.V.G. and D.M.L. analysed the data. All authors helped with editing the Article. J.V. supervised the work.

Corresponding author

Correspondence to Jelena Vučković .

Ethics declarations

Competing interests.

J.Y. and D.M.L. are cofounders of Brightlight Photonics, which is commercializing integrated Ti:sapphire lasers. K.V.G. is an advisor to Brightlight Photonics. J.Y., K.V.G. and D.M.L. hold equity in Brightlight Photonics. J.V., D.M.L., M.A.G. and G.H.A. are coinventors on a patent application related to integrated Ti:sapphire lasers (patent no. WO 2021/022188). J.V., J.Y., K.V.G. and D.M.L. are coinventors on a patent application related to integrated Ti:sapphire amplifiers.

Peer review

Peer review information.

Nature thanks Emir Salih Mağden, Johann Riemensberger and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended data fig. 1 diode-pumped on-chip ti:sapphire laser..

(a) Diagram of the measurement setup used in the diode-pumping experiments (MM: multi-mode, OSA: optical spectrum analyzer). (b) Measured optical spectrum of single-mode lasing at 848.7 nm and 858.3 nm, with a SMSR of 23.2 dB and 22.2 dB, respectively. (Inset) Image of the diode package used in these experiments.

Supplementary information

Supplementary information.

This file contains Supplementary Sections 1–10, including Supplementary Figs. 1–8, Supplementary Tables 1–3 and Supplementary References.

Peer Review File

Rights and permissions.

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Cite this article.

Yang, J., Van Gasse, K., Lukin, D.M. et al. Titanium:sapphire-on-insulator integrated lasers and amplifiers. Nature 630 , 853–859 (2024). https://doi.org/10.1038/s41586-024-07457-2

Download citation

Received : 05 October 2023

Accepted : 23 April 2024

Published : 26 June 2024

Issue Date : 27 June 2024

DOI : https://doi.org/10.1038/s41586-024-07457-2

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

By submitting a comment you agree to abide by our Terms and Community Guidelines . If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Quick links

• Explore articles by subject
• Guide to authors
• Editorial policies

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.